,,electricity ,,for ,,the ,,farm ,,the ,,macmillan ,,company ,,new ,,york ,,boston ,,chicago ,,dallas ,,atlanta ,,san ,,francisco ,,macmillan ,,co41 ,limited ,,london ,,bombay ,,calcutta ,,melbourne ,,the ,,macmillan ,,co4 ,,of ,,canada1 ,ltd4 ,,toronto ,illustration3 ,even the tiny trout brook becomes a thing of utility as well as of joy 7,courtesy of the ,fitz ,water ,wheel ,company1 ,hanover1 ,pa47 ,,electricity ,,for ,,the ,,farm ,,light1 ,,heat ,,and ,,power ,,by ,,inexpensive ,,methods ,,from ,,the ,,water ,,wheel ,,or ,,farm ,,engine ,,by ,,frederick ,,irving ,,anderson ,,author ,,of ,,the ,,farmer ,,of ,,to-,,morrow1 ,,etc41 ,,etc4 ,new ,york ,,the ,,macmillan ,,company #aiae ,all rights reserved ,copyright1 #aiae ,by ,,the ,,curtis ,,publishing ,,company ,the ,country ,gentleman ,copyright1 #aiae ,by ,,the ,,macmillan ,,company ,set up and electrotyped4 ,published ,april1 #aiae4 ,,preface ,this book is designed primarily to give the farmer a practical working knowledge of electricity for use as light1 heat1 and power on the farm4 ,the electric generator1 the dynamo1 is explained in detail2 and there are chapters on electric transmission and house-wiring1 by which the farm mechanic is enabled to install his own plant without the aid and expense of an expert4 ,with modern appliances1 within the means of the average farmer1 the generation of electricity1 with its unique conveniences1 becomes automatic1 provided some dependable source of power is to be had--such as a water wheel1 gasoline 7or other form of internal combustion7 engine1 or the ordinary windmill4 ,the water wheel is the ideal prime mover for the dynamo in isolated plants4 ,since water-power is running to waste on tens of thousands of our farms throughout the country1 several chapters are devoted to this phase of the subject3 these include descriptions and working diagrams of weirs and other simple devices for measuring the flow of streams2 there are tables and formulas by which any one1 with a knowledge of simple arithmetic1 may determine the power to be had from falling water under given conditions2 and in addition1 there are diagrams showing in general the method of construction of dams1 bulkheads1 races1 flumes1 etc41 from materials usually to be found on a farm4 ,the tiny unconsidered brook that waters the farm pasture frequently possesses power enough to supply the farmstead with clean1 cool1 safe light in place of the dangerous1 inconvenient oil lamp2 a small stream capable of developing from twenty-five to fifty horsepower will supply a farmer 7at practically no expense beyond the original cost of installation7 not only with light1 but with power for even the heavier farm operations1 as threshing2 and in addition will do the washing1 ironing1 and cooking1 and at the same time keep the house warm in the coldest weather4 ,less than one horsepower of energy will light the farmstead2 less than five horsepower of energy will provide light and small power1 and take the drudgery out of the kitchen4 ,for those not fortunate enough to possess water-power which can be developed1 there are chapters on the use of the farm gasoline engine and windmill1 in connection with the modern storage battery1 as sources of electric current4 ,it is desired to make acknowledgment for illustrations and assistance in gathering material for the book1 to the editors of ,the ,country ,gentleman1 ,philadelphia1 ,pa42 ,the ,crocker-,wheeler ,company1 ,ampere1 ,n4 ,j42 ,the ,general ,electric ,company1 ,schenectady1 ,n4 ,y42 the ,weston ,electrical ,instrument ,company1 of ,newark1 ,n4 ,j42 ,the ,chase ,turbine ,manufacturing ,company1 ,orange1 ,mass42 the ,c4 ,p4 ,bradway ,machine ,works1 ,west ,stafford1 ,conn42 ,the ,pelton ,water ,wheel ,company1 ,san ,francisco and ,new ,york2 the ,ward ,leonard ,manufacturing ,company1 ,bronxville1 ,n4 ,y42 ,the ,fairbanks1 ,morse ,company1 ,chicago2 and the ,fitz ,water ,wheel ,company1 ,hanover1 ,pa4 ,,table ,,of ,,contents ,,page ,,introduction xvii ,,part ,i ,,water-,,power ,,chapter ,i ,a ,,working ,,plant ,the agriculturist--,an old chair factory--,a neighbor's home-coming--,the idle wheel in commission again--,light1 heat and power for nothing--,advantages of electricity #c ,,chapter ,,ii ,a ,,little ,,prospecting ,small amount of water required for an electric plant--,exploring1 on a dull day--,a rough and ready weir--,what a little water will do--,the water wheel and the dynamo--,electricity consumed the instant it is produced--,the price of the average small plant1 not counting labor #bb ,,chapter ,,iii ,,how ,,to ,,measure ,,water-,,power ,what is a horsepower8--,how the ,carthaginians manufactured horsepower--,all that goes up must come down--,how the sun lifts water up for us to use--,water the ideal power for generating electricity--,the weir--,table for estimating flow of streams with a weir--,another method of measuring--,figuring water horsepower--,the size of the wheel--,what head is required--,quantity of water necessary #cb ,,chapter ,,iv ,,the ,,water ,,wheel ,,and ,,how ,,to ,,install ,,it ,different types of water wheels--,the impulse and the reaction wheels--,the impulse wheel adapted to high heads and small amount of water--,pipe lines--,table of resistance in pipes--,advantages and disadvantages of the impulse wheel--,other forms of impulse wheels--,the reaction turbine1 suited to low heads and large quantity of water--,its advantages and limitations--,developing a water-power project3 the dam2 the race2 the flume2 the penstock2 and the tailrace--,water rights for the farmer #ef ,,part ,,ii ,,electricity ,,chapter ,v ,,the ,,dynamo2 ,,what ,,it ,,does1 ,,and ,,how ,electricity compared to the heat and light of the ,sun--,the simple dynamo--,the amount of electric energy a dynamo will generate--,the modern dynamo--,measuring power in terms of electricity--,the volt--,the ampere--,the ohm--,the watt and the kilowatt--,ohm's ,law of the electric circuit1 and some examples of its application--,direct current1 and alternating current--,three types of direct-current dynamos3 series1 shunt1 and compound #hi ,,chapter ,,vi ,,what ,,size ,,plant ,,to ,,install ,the farmer's wife his partner--,little and big plants--,limiting factors--,fluctuations in water supply--,the average plant--,the actual plant--,amount of current required for various operations--,standard voltage--,a specimen allowance for electric light--,heating and cooking by electricity--,electric power3 the electric motor #aba ,,chapter ,,vii ,,transmission ,,lines ,copper wire--,setting of poles--,loss of power in transmission--,ohm's ,law and examples of how it is used in figuring size of wire--,copper-wire tables--,examples of transmission lines--,when to use high voltages--,over-compounding a dynamo to overcome transmission loss #aec ,,chapter ,,viii ,,wiring ,,the ,,house ,the insurance code--,different kinds of wiring described--,wooden moulding cheap and effective--,the distributing panel--,branch circuits--,protecting the circuits--,the use of porcelain tubes and other insulating devices--,putting up chandeliers and wall-brackets--,multiple connections--,how to connect a wall switch--,special wiring required for heat and power circuits--,knob and cleat wiring1 its advantages and disadvantages #agb ,,chapter ,,ix ,,the ,,electric ,,plant ,,at ,,work ,direct-connected generating sets--,belt drive--,the switchboard--,governors and voltage regulators--,methods of achieving constant pressure at all loads3 ,over-compounding the dynamo2 ,a system of resistances 7a home-made electric radiator72 ,regulating voltage by means of the rheostat--,automatic devices--,putting the plant in operation #aib ,,part ,,iii ,,gasoline ,,engines1 ,,windmills1 ,,etc4 ,,the ,,storage ,,batteries ,,chapter ,x ,,gasoline ,,engine ,,plants ,the standard voltage set--,two-cycle and four-cycle gasoline engines--,horsepower1 and fuel consumption--,efficiency of small engines and generators--,cost of operating a one-kilowatt plant #bag ,,chapter ,,xi ,,the ,,storage ,,battery ,what a storage battery does--,the lead battery and the ,edison battery--,economy of tungsten lamps for storage batteries--,the low-voltage battery for electric light--,how to figure the capacity of a battery--,table of light requirements for a farm house--,watt-hours and lamp-hours--,the cost of storage battery current--,how to charge a storage battery--,care of storage batteries #bbi ,,chapter ,,xii ,,battery ,,charging ,,devices ,the automatic plant most desirable--,how an automobile lighting and starting system works--,how the same results can be achieved in house lighting1 by means of automatic devices--,plants without automatic regulation--,care necessary--,the use of heating devices on storage battery current--,portable batteries--,an electricity route--,automobile power for lighting a few lamps #bej ,,illustrations ,even the tiny trout brook becomes a thing of utility as well as of joy ,frontispiece ,farm labor and materials built this crib and stone dam #ag ,measuring a small stream with a weir #bc ,efficient modern adaptations of the archaic undershot and overshot water wheels #ei ,a direct-current dynamo or motor1 showing details of construction #ib ,details of voltmeter or ammeter #abh ,instantaneous photograph of high-pressure water jet being quenched by buckets of a tangential wheel #aid ,a tangential wheel1 and a dynamo keyed to the same shaft--the ideal method for generating electricity #aid ,a rough-and-ready farm electric plant1 supplying two farms with light1 heat and power2 and a ,ward ,leonard-type circuit breaker for charging storage batteries #bdd ,,introduction ,the sight of a dozen or so fat young horses and mares feeding and frolicking on the wild range of the ,southwest would probably inspire the average farmer as an awful example of horsepower running to waste4 ,if1 by some miracle1 he came on such a sight in his own pastures1 he would probably consume much time practising the impossible art of creasing the wild creatures with a rifle bullet--after the style of ,kit ,carson and other free rovers of the old prairies when they were in need of a new mount4 ,he would probably spend uncounted hours behind the barn learning to throw a lariat2 and one fine day he would sally forth to capture a horsepower or two--and1 once captured1 he would use strength and strategy breaking the wild beast to harness4 ,a single horsepower--animal--will do the work of lifting #bc1jjj pounds one foot in one minute1 providing the animal is young1 and sound1 and is fed #ab quarts of oats and #aj or #ae pounds of hay a day1 and is given a chance to rest #af hours out of #bd--providing also it has a dentist to take care of its teeth occasionally1 and a blacksmith chiropodist to keep it in shoes4 ,on the hoof1 this horsepower is worth about #bjj--unless the farmer is looking for something fancy in the way of drafters1 when he will have to go as high as #djj for a big fellow4 ,and after #aj or #ae years1 the farmer would look around for another horse1 because an animal grows old4 ,this animal horsepower isn't a very efficient horsepower4 ,in fact1 it is less than three-fourths of an actual horsepower1 as engineers use the term4 ,a real horsepower will do the work of lifting #cc1jjj pounds one foot in one minute--or #eej pounds one foot in one second4 ,burn a pint of gasoline1 with #ad pounds of air1 in a gasoline engine1 and the engine will supply one #cc1jjj-pound horsepower for an hour4 ,the gasoline will cost about #b cents1 and the air is supplied free4 ,if it was the air that cost two cents a pound1 instead of the gasoline1 the automobile industry would undoubtedly stop where it began some fifteen years ago4 ,it is human nature1 however1 to grumble over this two cents4 ,yet the average farmer who would get excited if sound young chunks and drafters were running wild across his pastures1 is not inspired by any similar desire of possession and mastery by the sight of a brook1 or a rivulet that waters his meadows4 ,this brook or river is flowing down hill to the sea4 ,every #d1jjj gallons that falls one foot in one minute2 every #djj gallons that falls #aj feet in one minute2 or every #dj gallons that falls #ajj feet in one minute1 means the power of one horse going to waste--not the #bjj flesh-and-blood kind that can lift only #bc1jjj pounds a foot a minute--but the #cc1jjj foot-pound kind4 ,thousands of farms have small streams in their very dooryard1 capable of developing five1 ten1 twenty1 fifty horsepower twenty-four hours a day1 for the greater part of the year4 ,within a quarter of a mile of the great majority of farms 7outside of the dry lands themselves7 there are such streams4 ,only a small fraction of one per cent of them have been put to work1 made to pay their passage from the hills to the sea4 ,the ,united ,states government geological survey engineers recently made an estimate of the waterfalls capable of developing #a1jjj horsepower and over1 that are running to waste1 unused1 in this country4 ,they estimated that there is available1 every second of the day and night1 some #cj1jjj1jjj horsepower1 in dry weather--and twice this during the eight wet months of the year4 ,the waterfall capable of giving up #a1jjj horsepower in energy is not the subject of these chapters4 ,it is the small streams--the brooks1 the creeks1 the rivulets--which feed the #a1jjj horsepower torrents1 make them possible1 that are of interest to the farmer4 ,these small streams thread every township1 every county1 seeking the easiest way to the main valleys where they come together in great rivers4 ,what profitable crop on your farm removes the least plant food8 ,a bee-farmer enters his honey for the prize in this contest4 ,another farmer maintains that his ice-crop is the winner4 ,but electricity generated from falling water of a brook meandering across one's acres1 comes nearer to the correct answer of how to make something out of nothing4 ,it merely utilizes the wasted energy of water rolling down hill--the weight of water1 the pulling power of gravity4 ,water is still water1 after it has run through a turbine wheel to turn an electric generator4 ,it is still wet2 it is there for watering the stock2 and a few rods further down stream1 where it drops five or ten feet again1 it can be made to do the same work over again--and over and over again as long as it continues to fall1 on its journey to the sea4 ,the city of ,los ,angeles has a municipal water plant1 generating #bjj1jjj horsepower of electricity1 in which the water is used three times in its fall of #f1jjj feet2 and in the end1 where it runs out of the race in the valley1 it is sold for irrigation4 ,one water-horsepower will furnish light for the average farm2 five water-horsepower will furnish light and power1 and do the ironing and baking4 ,the cost of installing a plant of five water-horsepower should not exceed the cost of one sound young horse1 the #bjj kind--under conditions which are to be found on thousands of farms and farm communities in the ,east1 the ,central ,west1 and the ,pacific ,states4 ,this electrical horsepower will work #bd hours a day1 winter and summer1 and the farmer would not have to grow oats and hay for it on land that might better be used in growing food for human beings4 ,it would not become aged at the end of ten or fifteen years1 and the expense of maintenance would be practically nothing after the first cost of installation4 ,it would require only water as food--waste water4 ,two hundred and fifty cubic feet of water a minute1 falling ten feet1 will supply the average farm with all the conveniences of electricity4 ,this is a very modest creek--the kind of brook or creek that is ignored by the man who would think time well spent in putting in a week capturing a wild horse1 if a miracle should send such a beast within reach4 ,and the task of harnessing and breaking this water-horsepower is much more simple and less dangerous than the task of breaking a colt to harness4 ,,part ,i ,,water-,,power ,,electricity ,,for ,,the ,,farm ,,chapter ,i ,a ,,working ,,plant ,the agriculturist--,an old chair factory--,a neighbor's home-coming--,the idle wheel in commission again--,light1 heat and power for nothing--,advantages of electricity4 ,let us take an actual instance of one man who did go ahead and find out by experience just how intricate and just how simple a thing electricity from farm water-power is4 ,this man's name was ,perkins1 or1 we will call him that1 in relating this story4 ,perkins was what some people call1 not a farmer1 but an agriculturist1--that is1 he was a back-to-the-land man4 ,he had been born and raised on a farm4 ,he knew that you must harness a horse on the left side1 milk a cow on the right1 that wagon nuts tighten the way the wheel rims1 and that a fresh egg will not float4 ,he had a farm that would grow enough clover to fill the average dairy if he fed it lime2 he had a boy coming to school age2 and both he and his wife wanted to get back to the country4 ,they had their little savings1 and they wanted1 first of all1 to take a vacation1 getting acquainted with their farm4 ,they hadn't taken a vacation in fifteen years4 ,he moved in1 late in the summer1 and started out to get acquainted with his neighbors1 as well as his land4 ,this was in the ,new ,england hills4 ,water courses cut through everywhere4 ,in regard to its bountiful water supply1 the neighborhood had much in common with all the states east of the ,mississippi1 along the ,atlantic seaboard1 in the lake region of the central west1 and in the ,pacific ,states4 ,with this difference2 the water courses in his neighborhood had once been of economic importance4 ,a mountain river flowed down his valley4 ,up and down the valley one met ramshackle mills1 fallen into decay4 ,many years ago before railroads came1 before it was easy to haul coal from place to place to make steam1 these little mills were centers of thriving industries1 which depended on the power of falling water to make turned articles1 spin cotton1 and so forth4 ,then the railroads came1 and it was easy to haul coal to make steam4 ,and the same railroads that hauled the coal to make steam1 were there to haul away the articles manufactured by steam power4 ,so in time the little manufacturing plants on the river back in the hills quit business and moved to railroad stations4 ,then ,new ,england1 from being a manufacturing community made up of many small isolated water plants1 came to be a community made up of huge arteries and laterals of smoke stacks that fringed the railroads4 ,where the railroad happened to follow a river course--as the ,connecticut ,river--the water-power plants remained2 but the little plants back in the hills were wiped off the map--because steam power with railroads at the front door proved cheaper than water-power with railroads ten miles away4 ,one night ,perkins came in late from a long drive with his next-door neighbor4 ,he had learned the first rule of courtesy in the country1 which is to unhitch his own side of the horse and help back the buggy into the shed4 ,they stumbled around in the barn putting up the horse1 and getting down hay and grain for it1 by the light of an oil lantern1 which was set on the floor in a place convenient to be kicked over4 ,he went inside and took supper by the light of a smoky smelly oil lamp1 that filled the room full of dark corners2 and when supper was over1 the farmwife groped about in the cellar putting things away by the light of a candle4 ,the next day his neighbor was grinding cider at his ramshackle water mill--one of the operations for which a week must be set aside every fall4 ,perkins sat on a log and listened to the crunch-crunch of the apples in the chute1 and the drip of the frothy yellow liquid that fell into waiting buckets4 ,how much power have you got here8 he asked4 ,thirty or forty horsepower1 ,i guess4 ,what do you do with it1 besides grinding cider to pickle your neighbors' digestion with8 ,nothing much4 ,i've got a planer and a moulding machine in there1 to work up jags of lumber occasionally4 ,that's all4 ,this mill was a chair-factory in my grandfather's day1 back in #ahcj4 ,do you use it thirty days in a year8 ,no2 not half that4 ,what are you going to do with it this winter8 ,nothing2 ,i keep the gate open and the wheel turning1 so it won't freeze1 but nothing else4 ,i am going to take the family to ,texas to visit my wife's folks for three months4 ,we've worked hard enough to take a vacation4 ,will you rent me the mill while you are gone8 ,go ahead2 you can have it for nothing1 if you will watch the ice4 ,all right2 let me know when you come back and ,i'll drive to town and bring you home4 99 99 99 99 99 ,three months went by1 and one day in ,february the city man1 in response to a letter1 hitched up and drove to town to bring his neighbor back home4 ,it was four o'clock in the afternoon when they started out1 and it was six--dark--when they turned the bend in the road to the farm house4 ,they helped the wife and children out1 with their baggage1 and as ,perkins opened the door of the house1 he reached up on the wall and turned something that clicked sharply4 ,instantly light sprang from everywhere4 ,in the barn-yard a street lamp with an #ah-;inch reflector illuminated all under it for a space of #ajj feet with bright white rays of light4 ,another street lamp hung over the watering trough4 ,the barn doors and windows burst forth in light4 ,there was not a dark corner to be found anywhere4 ,in the house it was the same4 ,perkins led the amazed procession from room to room of the house they had shut up for the winter4 ,on the wall in the hall outside of every room was a button which he pushed1 and the room became as light as day before they entered4 ,the cellar door1 in opening1 automatically lighted a lamp illuminating that cavern as it had never been lighted before since the day a house was built over it4 ,needless to say1 the farmer and his family were reduced to a state of speechlessness4 ,how the deuce did you do it8 finally articulated the farmer4 ,i put your idle water wheel to work1 said ,perkins2 and then1 satisfied with this exhibition1 he put them back in the sleigh and drove to his home1 where his wife had supper waiting4 ,while the men were putting up the team in the electric lighted barn1 the farmwife went into the kitchen4 ,her hostess was cooking supper on an electric stove4 ,it looked like a city gas range and it cooked all their meals1 and did the baking besides4 ,a hot-water tank stood against the wall1 not connected to anything hot1 apparently4 ,but it was scalding hot1 by virtue of a little electric water heater the size of a quart tin can1 connected at the bottom4 ,twenty-four hours a day the water wheel pumped electricity into that can1 so that hot water was to be had at any hour simply by turning a faucet4 ,in the laundry there was an electric pump that kept the tank in the attic filled automatically4 ,when the level of water in this tank fell to a certain point1 a float operated a switch that started the pump2 and when the water level reached a certain height1 the same float stopped the pump4 ,a small motor1 the size of a medium ,hubbard squash operated a washing machine and wringer on wash days4 ,this same motor was a man-of-all-work for this house1 for1 when called on1 it turned the separator1 ground and polished knives and silverware1 spun the sewing machine1 and worked the vacuum cleaner4 ,over the dining room table hung the same hanging shade of old days1 but the oil lamp itself was gone4 ,in its place was a #ajj-watt tungsten lamp whose rays made the white table cloth fairly glisten4 ,the wires carrying electricity to this lamp were threaded through the chains reaching to the ceiling1 and one had to look twice to see where the current came from4 ,in the sitting room1 a cluster of electric bulbs glowed from a fancy wicker work basket that hung from the ceiling4 ,the housewife had made use of what she had throughout the house4 ,old-fashioned candle-shades sat like cocked hats astride electric bulbs4 ,there is little heat to an electric bulb for the reason that the white-hot wire that gives the light is made to burn in high vacuum1 which transmits heat very slowly4 ,the housewife had taken advantage of this fact and from every corner gleamed lights dressed in fancy designs of tissue paper and silk4 ,now we will talk business1 said ,perkins when supper was over and they had lighted their pipes4 ,the returned native looked dubious4 ,his ,new ,england training had warned him long ago that one cannot expect to get something for nothing1 and he felt sure there was a joker in this affair4 ,how much do ,i owe you8 he asked4 ,nothing1 said ,perkins4 ,you furnish the water-power with your idle wheel1 and ,i furnish the electric installation4 ,this is only a small plant ,i have put in1 but it gives us enough electricity to go around1 with a margin for emergencies4 ,i have taken the liberty of wiring your house and your horse-barn and cow-barn and your barn-yard4 ,altogether1 ,i suppose you have #cj lights about the place1 and during these long winter days you will keep most of them going from #c to #e hours a night and #b or #c hours in the early morning4 ,if you were in town1 those lights would cost you about #ab cents an hour1 at the commercial rate of electricity4 ,say #fj cents a day--eighteen dollars a month4 ,that isn't a very big electric light bill for some people ,i know in town--and they consider themselves lucky to have the privilege of buying electricity at that rate4 ,your wheel is running all winter to prevent ice from forming and smashing it4 ,it might just as well be spinning the dynamo4 ,if you think it worth while1 continued ,perkins1--this #ah worth of light you have on tap night and morning1 or any hour of the day1--we will say the account is settled4 ,that is1 of course1 if you will give me the use of half the electricity that your idle wheel is grinding out with my second-hand dynamo4 ,we have about eight electrical horsepower on our wires1 without overloading the machine4 ,next spring ,i am going to stock up this place2 and ,i think about the first thing ,i do1 when my dairy is running1 will be to put in a milking machine and let electricity do the milking for me4 ,it will also fill my silo1 grind my mowing-machine knives1 saw my wood1 and keep water running in my barn4 ,you will probably want to do the same4 ,but what it does for us men in the barn and barn-yard1 isn't to be compared to what it does for the women in the house4 ,when my wife wants a hot oven she presses a button4 ,when she wants to put the 'fire' out1 she presses another4 ,that's all there is to it4 ,no heat1 no smoke1 no ashes4 ,the same with ironing--and washing4 ,no oil lamps to fill1 no wicks to trim1 no chimneys to wash1 no kerosene to kick over and start a fire4 ,you say the current you have put in my house would cost me about #ah a month1 in town4 ,yes1 about that4 ,making electricity from coal costs money4 ,what does it cost here8 ,practically nothing4 ,your river1 that has been running to waste ever since your grandfather gave up making chairs1 does the work4 ,there is nothing about a dynamo to wear out1 except the bearings1 and these can be replaced once every five or ten years for a trifle4 ,the machine needs to be oiled and cared for--fill the oil cups about once in three days4 ,your water wheel needs the same attention4 ,that's all there is to it4 ,you can figure the cost of your current yourself--just about the cost of the lubricating oil you use--and the cost of the time you give it--about the same time you give to any piece of good machinery1 from a sulky plow to a cream separator4 ,this is a true story4 ,this electric plant1 where ,perkins furnishes the electric end1 and his neighbor the water-power1 has been running now for two years1 grinding out electricity for the two places twenty-four hours a day4 ,perkins was not an electrical engineer4 ,he was just a plain intelligent ,american citizen who found sufficient knowledge in books to enable him to install and operate this plant4 ,frequently he is away for long periods1 but his neighbor 7who has lost his original terror of electricity7 takes care of the plant4 ,in fact1 this farmer has given a lot of study to the thing1 through curiosity1 until he knows fully as much about it now as his city neighbor4 ,he had the usual idea1 at the start1 that a current strong enough to light a #ajj candlepower lamp would kick like a mule if a man happened to get behind it4 ,he watched the city man handle bare wires and finally he plucked up courage to do it himself4 ,it was a #aaj-volt current1 the pressure used in our cities for domestic lighting4 ,the funny part about it was1 the farmer could not feel it at all at first4 ,his fingers were calloused and no current could pass through them4 ,finally he sandpapered his fingers and tried it again4 ,then he was able to get the tickle of #aaj volts4 ,it wasn't so deadly after all--about the strength of a weak medical battery1 with which every one is familiar4 ,a current of #aaj volts cannot do any harm to the human body unless contact is made over a very large surface1 which is impossible unless a man goes to a lot of trouble to make such a contact4 ,a current of #bbj volts pressure--the pressure used in cities for motors--has a little more kick to it1 but still is not uncomfortable4 ,when the pressure rises to #ejj volts 7the pressure used in trolley wires for street cars71 it begins to be dangerous4 ,but there is no reason why a farm plant should be over #aaj volts1 under usual conditions2 engineers have decided on this pressure as the best adapted to domestic use1 and manufacturers who turn out the numerous electrical devices1 such as irons1 toasters1 massage machines1 etc41 fit their standard instruments to this voltage4 ,illustration3 ,farm labor and materials built this crib and stone dam ,as to the cost of this co-operative plant--it was in the neighborhood of #bjj4 ,as we have said1 it provided eight electrical horsepower on tap at any hour of the day or night--enough for the two farms1 and a surplus for neighbors1 if they wished to string lines and make use of it4 ,the dynamo1 a direct-current machine1 #aaj volts pressure1 and what is known in the trade as compound1--that is1 a machine that maintains a constant pressure automatically and does not require an attendant--was picked up second-hand1 through a newspaper ad and cost #ij4 ,the switchboard1 a make-shift affair1 not very handsome1 but just as serviceable as if it were made of marble1 cost less than #be all told4 ,the transmission wire cost #ai a hundred pounds2 it is of copper1 and covered with weatherproofed tape4 ,perkins bought a #ej-;cent book on house-wiring1 and did the wiring himself1 the way the book told him to1 a simple operation4 ,for fixtures1 as we have said1 his wife devised fancy shades out of ,mexican baskets1 tissue paper1 and silk1 in which are hidden electric globes that glow like fire-flies at the pressing of a button4 ,the lamps themselves are mostly old-style carbon lamps1 which can be bought at #af cents each retail4 ,in his living room and dining room he used the new-style tungsten lamps instead of old-style carbon4 ,these cost #cj cents each4 ,incandescent lamps are rated for #a1jjj hours useful life4 ,the advantage of tungsten lights is that they give three times as much light for the same expenditure of current as carbon lights4 ,this is a big advantage in the city1 where current is costly2 but it is not so much of an advantage in the country where a farmer has plenty of water-power--because his current costs him practically nothing1 and he can afford to be wasteful of it to save money in lamps4 ,another advantage he has over his city cousin3 ,in town1 an incandescent lamp is thrown away after it has been used #a1jjj hours because after that it gives only #hj of the light it did when new--quite an item when one is paying for current4 ,the experience of ,perkins and his neighbor in their coperative plant has been that they have excess light anyway1 and if a few bulbs fall off a fifth in efficiency1 it is not noticeable4 ,as a matter of fact most of their bulbs have been in use without replacing for the two years the plant has been in operation4 ,the lamps are on the wall or the ceiling1 out of the way1 not liable to be broken2 so the actual expense in replacing lamps is less than for lamp chimneys in the old days4 ,insurance companies recognize that a large percentage of farm fires comes from the use of kerosene2 for this reason1 they are willing to make special rates for farm homes lighted by electricity4 ,they prescribe certain rules for wiring a house1 and they insist that their agent inspect and pass such wiring before current is turned on4 ,once the wiring is passed1 the advantage is all in favor of the farmer with electricity over the farmer with kerosene4 ,the ,national ,board of ,fire ,underwriters is sufficiently logical in its demands1 and powerful enough1 so that manufacturers who turn out the necessary fittings find no sale for devices that do not conform to insurance standards4 ,therefore it is difficult to go wrong in wiring a house4 ,finally1 as to the added value a water-power electric plant adds to the selling price of a farm4 ,let the farmer answer this question for himself4 ,if he can advertise his farm for sale1 with a paragraph running3 ,hydroelectric plant on the premises1 furnishing electricity for light1 heat1 and power--what do you suppose a wide-awake purchaser would be willing to pay for that8 ,perkins and his neighbor believe that #a1jjj is a very modest estimate added by their electric plant to both places4 ,and they talk of doing still more4 ,they use only a quarter of the power of the water that is running to waste through the wheel4 ,they are figuring on installing a larger dynamo1 of say #cj electrical horse-power1 which will provide clean1 dry1 safe heat for their houses even on the coldest days in winter4 ,when they have done this1 they will consider that they are really putting their small river to work4 ,,chapter ,,ii ,a ,,little ,,prospecting ,small amount of water required for an electric plant--,exploring1 on a dull day--,a rough and ready weir--,what a little water will do--,the water wheel and the dynamo--,electricity consumed the instant it is produced--,the price of the average small plant1 not counting labor4 ,the average farmer makes the mistake of considering that one must have a river of some size to develop power of any practical use4 ,on your next free day do a little prospecting4 ,we have already said that #bej cubic feet of water falling #aj feet a minute will provide light1 heat and small motor power for the average farm4 ,a single water horsepower will generate enough electricity to provide light for the house and barn4 ,but let us take five horsepower as a desirable minimum in this instance4 ,illustration3 ,measuring a small stream with a weir ,in your neighborhood there is a creek three or four feet wide1 toiling along day by day1 at its task of watering your fields4 ,find a wide board a little longer than the width of this creek you have scorned4 ,set it upright across the stream between the banks1 so that no water flows around the ends or under it4 ,it should be high enough to set the water back to a dead level for a few feet upstream1 before it overflows4 ,cut a gate in this board1 say three feet wide and ten inches deep1 or according to the size of a stream4 ,cut this gate from the top1 so that all the water of the stream will flow through the opening1 and still maintain a level for several feet back of the board4 ,this is what engineers call a weir1 a handy contrivance for measuring the flow of small streams4 ,experts have figured out an elaborate system of tables as to weirs4 ,all we need to do now1 in this rough survey1 is to figure out the number of square inches of water flowing through this opening and falling on the other side4 ,with a rule1 measure the depth of the overflowing water1 from the bottom of the opening to the top of the dead level of the water behind the board4 ,multiply this depth by the width of the opening1 which will give the square inches of water escaping4 ,for every square inch of this water escaping1 engineers tell us that stream is capable of delivering1 roughly1 one cubic foot of water a minute4 ,thus1 if the water is #h inches deep in an opening #cb inches wide1 then the number of cubic feet this stream is delivering each minute is #h times #cb1 or #bef cubic feet a minute4 ,so1 a stream #cb inches wide1 with a uniform depth of #h inches running through our weir is capable of supplying the demands of the average farm in terms of electricity4 ,providing1 of course1 that the lay of the land is such that this water can be made to fall #aj feet into a water wheel4 ,go upstream and make a rough survey of the fall4 ,in the majority of instances 7unless this is some sluggish stream in a flat prairie7 it will be found feasible to divert the stream from its main channel by means of a race--an artificial channel--and to convey it to a not far-distant spot where the necessary fall can be had at an angle of about #cj degrees from horizontal4 ,if you find there is twice as much water as you need for the amount of power you require1 a five-foot fall will give the same result4 ,or1 if there is only one-half as much water as the #bej cubic feet specified1 you can still obtain your theoretical five horsepower if the means are at hand for providing a fall of twenty feet instead of ten4 ,do not make the very common mistake of figuring that a stream is delivering a cubic foot a minute to each square inch of weir opening1 simply because it fills a certain opening4 ,it is the excess water1 falling over the opening1 after the stream has set back to a permanent dead level1 that is to be measured4 ,this farmer who spends an idle day measuring the flow of his brook with a notched board1 may say here3 ,this is all very well4 ,this is the spring of the year1 when my brook is flowing at high-water mark4 ,what am ,i going to do in the dry months of summer1 when there are not #bej cubic feet of water escaping every minute8 ,there are several answers to this question1 which will be taken up in detail in subsequent chapters4 ,here1 let us say1 even if this brook does flow in sufficient volume only #h months in a year--the dark months1 by the way1--is not electricity and the many benefits it provides worth having eight months in the year8 ,my garden provides fresh vegetables four months a year4 ,because it withers and dies and lies covered with snow during the winter1 is that any reason why ,i should not plow and manure and plant my garden when spring comes again8 ,a water wheel1 the modern turbine1 is a circular fan with curved iron blades1 revolving in an iron case4 ,water1 forced through the blades of this fan by its own weight1 causes the wheel to revolve on its axis2 and the fan1 in turn causes a shaft fitted with pulleys to revolve4 ,the water1 by giving the iron-bladed fan a turning movement as it rushes through1 imparts to it mechanical power4 ,the shaft set in motion by means of this mechanical power is1 in turn1 belted to the pulley of a dynamo4 ,this dynamo consists1 first1 of a shaft on which is placed a spool1 wound in a curious way1 with many turns of insulated copper wire4 ,this spool revolves freely in an air space surrounded by electric magnets4 ,the spool does not touch these magnets4 ,it is so nicely balanced that the weight of a finger will turn it4 ,yet1 when it is revolved by water-power at a predetermined speed--say #a1ejj revolutions a minute--it generates electricity1 transforms the mechanical power of the water wheel into another form of energy--a form of energy which can be carried for long distances on copper wires1 which can1 by touching a button1 be itself converted into light1 or heat1 or back into mechanical energy again4 ,if two wires be led from opposite sides of this revolving spool1 and an electric lamp be connected from one to the other wire1 the lamp will be lighted--will grow white hot1--hence incandescent light4 ,the instant this lamp is turned on1 the revolving spool feels a stress1 the magnets by which it is surrounded begin to pull back on it4 ,the power of the water wheel1 however1 overcomes this pull4 ,if one hundred lights be turned on1 the backward pull of the magnets surrounding the spool will be one hundred times as strong as for one light4 ,for every ounce of electrical energy used in light or heat or power1 the dynamo will require a like ounce of mechanical power from the water wheel which drives it4 ,the story is told of a canny ,scotch engineer1 who1 in the first days of dynamos1 not so very long ago1 scoffed at the suggestion that such a spool1 spinning in free air1 in well lubricated bearings1 could bring his big ,corliss steam engine to a stop4 ,yet he saw it done simply by belting this spool1 a dynamo1 to his engine and asking the dynamo for more power in terms of light than his steam could deliver in terms of mechanical power to overcome the pull of the magnets4 ,electricity must be consumed the instant it is generated 7except in rare instances where small amounts are accumulated in storage batteries by a chemical process74 ,the pressure of a button1 or the throw of a switch causes the dynamo instantly to respond with just enough energy to do the work asked of it1 always in proportion to the amount required4 ,having this in mind1 it is rather curious to think of electricity as being an article of export1 an item in international trade4 ,yet in #aiac hydro-electric companies in ,canada exported by means of wires1 to this country over #ggb1jjj1jjj kilowatt-hours 7over one billion horsepower hours7 of electricity for use in factories near the boundary line4 ,this #bej cubic feet of water per minute then1 which the farmer has measured by means of his notched board1 will transform by means of its falling weight mechanical power into a like amount of electrical power--less friction losses1 which may amount to as much as #fj in very small machines1 and #ae in larger plants4 ,that is1 the brook which has been draining your pastures for uncounted ages contains the potential power of #c and #d young horses--with this difference3 that it works #bd hours a day1 runs on forever1 and requires no oats or hay4 ,and the cost of such an electric plant1 which is ample for the needs of the average farm1 is in most cases less than the price of a good farm horse--the #bjj kind--not counting labor of installation4 ,it is the purpose of these chapters to awaken the farmer to the possibilities of such small water-power as he or his community may possess2 to show that the generating of electricity is a very simple operation1 and that the maintenance and care of such a plant is within the mechanical ability of any ,american farmer or farm boy2 and to show that electricity itself is far from being the dangerous death-dealing fluid of popular imagination4 ,electricity must be studied2 and then it becomes an obedient1 tireless servant4 ,during the past decade or two1 mathematical wizards have studied electricity1 explored its atoms1 reduced it to simple arithmetic--and although they cannot yet tell us why it is generated1 they tell us how4 ,it is with this simple arithmetic1 and the necessary manual operations that we have to do here4 ,,chapter ,,iii ,,how ,,to ,,measure ,,water-,,power ,what is a horsepower8--,how the ,carthaginians manufactured horsepower--,all that goes up must come down--,how the sun lifts water up for us to use--,water the ideal power for generating electricity--,the weir--,table for estimating flow of streams1 with a weir--,another method of measuring--,figuring water horsepower--,the size of the wheel--,what head is required--,quantity of water necessary4 ,if a man were off in the woods and needed a horsepower of energy to work for him1 he could generate it by lifting #eej pounds of stone or wood1 or whatnot1 one foot off the ground1 and letting it fall back in the space of one second4 ,as a man possesses capacity for work equal to one-fifth horsepower1 it would take him five seconds to do the work of lifting the weight up that the weight itself accomplished in falling down4 ,all that goes up must come down2 and by a nice balance of physical laws1 a falling body hits the ground with precisely the same force as is required to lift it to the height from which it falls4 ,the ,carthaginians1 and other ancients 7who were deep in the woods as regards mechanical knowledge7 had their slaves carry huge stones to the top of the city wall2 and the stones were placed in convenient positions to be tipped over on the heads of any besieging army that happened along4 ,thus by concentrating the energy of many slaves in one batch of stones1 the warriors of that day were enabled to deliver horsepower in one mass where it would do the most good4 ,the farmer who makes use of the energy of falling water to generate electricity for light1 heat1 and power does the same thing--he makes use of the capacity for work stored in water in being lifted to a certain height4 ,as in the case of the gasoline engine1 which burns #ad pounds of air for every pound of gasoline1 the engineer of the water-power plant does not have to concern himself with the question of how this natural source of energy happened to be in a handy place for him to make use of it4 ,the sun1 shining on the ocean1 and turning water into vapor by its heat has already lifted it up for him4 ,this vapor floating in the air and blown about by winds1 becomes chilled from one cause or another1 gives up its heat1 turns back into water1 and falls as rain4 ,this rain1 falling on land five1 ten1 a hundred1 a thousand1 or ten thousand feet above the sea level1 begins to run back to the sea1 picking out the easiest road and cutting a channel that we call a brook1 a stream1 or a river4 ,our farm lands are covered to an average depth of about three feet a year with water1 every gallon of which has stored in it the energy expended by the heat of the sun in lifting it to the height where it is found4 ,the farmer1 prospecting on his land for water-power1 locates a spot on a stream which he calls ,supply2 and another spot a few feet down hill near the same stream1 which he calls ,power4 ,every gallon of water that falls between these two points1 and is made to escape through the revolving blades of a water wheel is capable of work in terms of foot-pounds--an amount of work that is directly proportional to the quantity of water1 and to the distance in feet which it falls to reach the wheel--pounds and feet4 ,the ,efficient ,water ,wheel ,and it is a very efficient form of work1 too4 ,in fact it is one of the most efficient forms of mechanical energy known--and one of the easiest controlled4 ,a modern water wheel uses #he per cent of the total capacity for work imparted to falling water by gravity1 and delivers it as rotary motion4 ,compare this water wheel efficiency with other forms of mechanical power in common use3 ,whereas a water wheel uses #he per cent of the energy of its water supply1 and wastes only #ae per cent1 a gasoline engine reverses the table1 and delivers only #ae per cent of the energy in gasoline and wastes #he per cent--and it is rather a high-class gasoline engine that can deliver even #ae per cent2 a steam engine1 on the other hand1 uses about #ag per cent of the energy in the coal under its boilers and passes the rest up the chimney as waste heat and smoke4 ,there is still another advantage possessed by water-power over its two rivals1 steam and gas3 ,it gives the most even flow of power4 ,a gas engine kicks a wheel round in a circle1 by means of successive explosions in its cylinders4 ,a reciprocating steam engine kicks a wheel round in a circle by means of steam expanding first in one direction1 then in another4 ,a water wheel1 on the other hand1 is made to revolve by means of the pressure of water--by the constant force of gravity1 itself--weight4 ,weight is something that does not vary from minute to minute1 or from one fraction of a second to another4 ,it is always the same4 ,a square inch of water pressing on the blades of a water wheel weights ten1 twenty1 a hundred pounds1 according to the height of the pipe conveying that water from the source of supply1 to the wheel4 ,so long as this column of water is maintained at a fixed height1 the power it delivers to the wheel does not vary by so much as the weight of a feather4 ,this property of falling water makes it the ideal power for generating electricity4 ,electricity generated from mechanical power depends on constant speed for steady pressure--since the electric current1 when analyzed1 is merely a succession of pulsations through a wire1 like waves beating against a sea wall4 ,water-power delivers these waves at a constant speed1 so that electric lights made from water-power do not flicker and jump like the flame of a lantern in a gusty wind4 ,on the other hand1 to accomplish the same thing with steam or gasoline requires an especially constructed engine4 ,the ,simple ,weir ,since a steady flow of water1 and a constant head1 bring about this ideal condition in the water wheel1 the first problem that faces the farmer prospector is to determine the amount of water which his stream is capable of delivering4 ,this is always measured1 for convenience1 in cubic feet per minute4 7,a cubic foot of water weighs #fb4e pounds1 and contains #g-a_/b gallons47 ,this measurement is obtained in several ways1 among which probably the use of a weir is the simplest and most accurate1 for small streams4 ,a weir is1 in effect1 merely a temporary dam set across the stream in such a manner as to form a small pond2 and to enable one to measure the water escaping from this pond4 ,it may be likened to the overflow pipe of a horse trough which is being fed from a spring4 ,to measure the flow of water from such a spring1 all that is necessary is to measure the water escaping through the overflow when the water in the trough has attained a permanent level4 ,illustration3 ,detail of home-made weir ,illustration3 ,cross-section of weir ,the diagrams show the cross-section and detail of a typical weir1 which can be put together in a few minutes with the aid of a saw and hammer4 ,the cross-section shows that the lower edge of the slot through which the water of the temporary pond is made to escape1 is cut on a bevel1 with its sharp edge upstream4 ,the wing on each side of the opening is for the purpose of preventing the stream from narrowing as it flows through the opening1 and thus upsetting the calculations4 ,this weir should be set directly across the flow of the stream1 perfectly level1 and upright4 ,it should be so imbedded in the banks1 and in the bottom of the stream1 that no water can escape1 except through the opening cut for that purpose4 ,it will require a little experimenting with a rough model to determine just how wide and how deep this opening should be4 ,it should be large enough to prevent water flowing over the top of the board2 and it should be small enough to cause a still-water pond to form for several feet behind the weir4 ,keep in mind the idea of the overflowing water trough when building your weir4 ,the stream1 running down from a higher level behind1 should be emptying into a still-water pond1 which in turn should be emptying itself through the aperture in the board at the same rate as the stream is keeping the pond full4 ,your weir should be fashioned with the idea of some permanency so that a number of measurements may be taken1 extending over a period of time--thus enabling the prospector to make a reliable estimate not only of the amount of water flowing at any one time1 but of its fluctuations4 ,under expert supervision1 this simple weir is an exact contrivance--exact enough1 in fact1 for the finest calculations required in engineering work4 ,to find out how many cubic feet of water the stream is delivering at any moment1 all that is necessary is to measure its depth where it flows through the opening4 ,there are instruments1 like the hook-gauge1 which are designed to measure this depth with accuracy up to one-thousandth of an inch4 ,an ordinary foot rule1 or a folding rule1 will give results sufficiently accurate for the water prospector in this instance4 ,the depth should be measured not at the opening itself1 but a short distance back of the opening1 where the water is setting at a dead level and is moving very slowly4 ,with this weir1 every square inch of water flowing through the opening indicates roughly one cubic foot of water a minute4 ,thus if the opening is #aj inches wide and the water flowing through it is #e inches deep1 the number of cubic feet a minute the stream is delivering is #aj #e #ej square inches #ej cubic feet a minute4 ,this is a very small stream2 yet1 if it could be made to fall through a water wheel #aj feet below a pond or reservoir1 it would exert a continuous pressure of #cj1jjj pounds per minute on the blades of the wheel--nearly one theoretical horsepower4 ,this estimate of one cubic foot to each square inch is a very rough approximation4 ,engineers have developed many complicated formulas for determining the flow of water through weirs1 taking into account fine variations that the farm prospector need not heed4 ,the so-called ,francis formula1 developed by a long series of actual experiments at ,lowell1 ,mass41 in #aheb by ,mr4 ,james ,b4 ,francis1 with weirs #aj feet long and #e feet #b inches high1 is standard for these calculations and is expressed 7for those who desire to use it for special purposes7 as follows3 ,q #c4cc ,l ,h7#c_/b7 or1 ,q #c4cc ,l ,h sqrt7,h71 in which ,q means quantity of water in cubic feet per second1 ,l is length of opening1 in feet2 and ,h is height of opening in feet4 ,the following table is figured according to the ,francis formula1 and gives the discharge in cubic feet per minute1 for openings one inch wide3 ,,table ,,of ,,weirs ,inches #j #a_/d #a_/b #c_/d #a #j4djc #j4efc #j4gdj #j4iff #b #a4ada #a4cfj #a4eic #a4hch #c #b4jid #b4cfa #b4fci #b4ibg #d #c4bbe #c4eca #c4hdh #d4agc #e #d4ejf #d4hdi #e4bjj #e4eeh #f #e4ibe #f4bih #f4fha #g4jga #g #g4dfe #g4hfi #h4bhj #h4fig #h #i4aba #i4eeb #i4iij #aj4dbg #i #aj4hhd #aa4cdj #aa4hjd #ab4bgb #aj #ab4gdg #ac4bbh #ac4gaf #ad4bjh #aa #ad4gjg #ae4baa #ae4gba #af4bcf #ab #af4geg #ag4bhc #ag4haf #ah4ceb #ac #ah4hie #ai4dde #ai4iif #bj4eeh #ad #ba4aaf #ba4fhd #bb4beh #bb4hce #ae #bc4dah #bd4jjg #bd4fjj #be4aie #af #be4hjj #bf4djf #bg4jai #bg4fcd #ag #bh4bef #bh4hha #bi4eab #cj4ade #ah #cj4ghe #ca4dbi #cb4jge #cb4gcc ,thus1 let us say1 our weir has an opening #cj inches wide1 and the water overflows through the opening at a uniform depth of #f-a_/d inches1 when measured a few inches behind the board at a point before the overflow curve begins4 ,run down the first column on the left to #f1 and cross over to the second column to the right1 headed #a_/d4 ,this gives the number of cubic feet per minute for this depth one inch wide1 as #f4bih4 ,since the weir is #cj inches wide1 multiply #f4bih #cj #ahh4id--or1 say1 #ahi cubic feet per minute4 ,once the weir is set1 it is the work of but a moment to find out the quantity of water a stream is delivering1 simply by referring to the above table4 ,another ,method of ,measuring a ,stream ,weirs are for use in small streams4 ,for larger streams1 where the construction of a weir would be difficult1 the ,u4 ,s4 ,geological ,survey engineers recommend the following simple method3 ,choose a place where the channel is straight for #ajj or #bjj feet1 and has a nearly constant depth and width2 lay off on the bank a line #ej or #ajj feet in length4 ,throw small chips into the stream1 and measure the time in seconds they take to travel the distance laid off on the bank4 ,this gives the surface velocity of the water4 ,multiply the average of several such tests by #j4hj1 which will give very nearly the mean velocity4 ,then it is necessary to find the cross-section of the flowing water 7its average depth multiplied by width71 and this number1 in square feet1 multiplied by the velocity in feet per second1 will give the number of cubic feet the stream is delivering each second4 ,multiplied by #fj gives cubic feet a minute4 ,figuring a ,stream's ,horsepower ,by one of the above simple methods1 the problem of ,quantity can easily be determined4 ,the next problem is to determine what ,head can be obtained4 ,head is the distance in feet the water may be made to fall1 from the ,source of ,supply1 to the water wheel itself4 ,the power of water is directly proportional to head1 just as it is directly proportional to quantity4 ,thus the typical weir measured above was #cj inches wide and #f-a_/d deep1 giving #ahi cubic feet of water a minute--,quantity4 ,since such a stream is of common occurrence on thousands of farms1 let us analyze briefly its possibilities for power3 ,one hundred and eighty-nine cubic feet of water weighs #ahi #fb4e pounds #aa1hab4e pounds4 ,drop this weight one foot1 and we have #aa1hab4e foot-pounds4 ,drop it #c feet and we have #aa1hab #c #ce1dcg4e foot-pounds4 ,since #cc1jjj foot-pounds exerted in one minute is one horsepower1 we have here a little more than one horsepower4 ,for simplicity let us call it a horsepower4 ,illustration3 ,detail of a water-power plant1 showing setting of wheel1 and dynamo connection ,now1 since the work to be had from this water varies directly with quantity and head1 it is obvious that a stream one-half as big falling twice as far1 would still give one horsepower at the wheel2 or1 a stream of #ahi cubic feet a minute falling ten times as far1 #cj feet1 would give ten times the power1 or ten horsepower2 a stream falling one hundred times as far would give one hundred horsepower4 ,thus small quantities of water falling great distances1 or large quantities of water falling small distances may accomplish the same results4 ,from this it will be seen1 that the simple formula for determining the theoretical horsepower of any stream1 in which ,quantity and ,head are known1 is as follows3 ,cu4 ,ft4 per ,feet minute head #fb4e 7,a7 ,theoretical ,horsepower ---------------------- #cc1jjj ,as an example1 let us say that we have a stream whose weir measurement shows it capable of delivering #cgf cubic feet a minute1 with a head 7determined by survey7 of #ac feet #f inches4 ,what is the horsepower of this stream8 ,answer3 ,cu4 ft4 p4 m4 head pounds #cgf #ac4e #fb4e ,h4,p4 ----------------------------- #i4fad horsepower #cc1jjj ,this is theoretical horsepower4 ,to determine the actual horsepower that can be counted on1 in practice1 it is customary1 with small water wheels1 to figure #be per cent loss through friction1 etc4 ,in this instance1 the actual horsepower would then be #g4b4 ,the ,size of the ,wheel ,water wheels are not rated by horsepower by manufacturers1 because the same wheel might develop one horsepower or one hundred horsepower1 or even a thousand horsepower1 according to the conditions under which it is used4 ,with a given supply of water1 the head1 in feet1 determines the size of wheel necessary4 ,the farther a stream of water falls1 the smaller the pipe necessary to carry a given number of gallons past a given point in a given time4 ,a small wheel1 under #aj #ac4e ft4 head1 would give the same power with the above #cgf cubic feet of water a minute1 as a large wheel would with #aj #cgf cubic feet1 under a #ac4e foot head4 ,this is due to the acceleration of gravity on falling bodies4 ,a rifle bullet shot into the air with a muzzle velocity of #c1jjj feet a second begins to diminish its speed instantly on leaving the muzzle1 and continues to diminish in speed at the fixed rate of #cb4af feet a second1 until it finally comes to a stop1 and starts to descend4 ,then1 again1 its speed accelerates at the rate of #cb4af feet a second1 until on striking the earth it has attained the velocity at which it left the muzzle of the rifle1 less loss due to friction4 ,the acceleration of gravity affects falling water in the same manner as it affects a falling bullet4 ,at any one second1 during its course of fall1 it is traveling at a rate #cb4af feet a second in excess of its speed the previous second4 ,in figuring the size wheel necessary under given conditions or to determine the power of water with a given nozzle opening1 it is necessary to take this into account4 ,the table on page #ea gives velocity per second of falling water1 ignoring the friction of the pipe1 in heads from #e to #ajjj feet4 ,the scientific formula from which the table is computed is expressed as follows1 for those of a mathematical turn of mind3 ,velocity 7ft4 per sec47 sqrt7#b;gh72 or1 velocity is equal to the square root of the product 7g #cb4af1--times head in feet1 multiplied by #b74 ,,spouting ,,velocity ,,of ,,water1 ,,in ,,feet ,,per ,,second1 ,,in ,,heads ,,of ,,from #e ,,to #a1jjj ,,feet ,head ,velocity #e #ag4i #f #ai4g #g #ba4b #h #bb4g #i #bd4a #aj #be4d #aa #bf4f #aa4e #bg4b #ab #bg4h #ab4e #bh4d #ac #bh4i #ac4e #bi4e #ad #cj4j #ad4e #cj4e #ae #ca4c #ae4e #ca4f #af #cb4a #af4e #cb4f #ag #cc4a #ag4e #cc4f #ah #cd4j #ah4e #cd4e #ai #ce4j #ai4e #ce4d #bj #ce4i #bj4e #cf4c #ba #cf4h #ba4e #cg4b #bb #cg4f #bb4e #ch4a #bc #ch4e #bc4e #ch4i #bd #ci4c #bd4e #ci4g #be #dj4a #bf #dj4i #bg #da4g #bh #db4e #bi #dc4b #cj #dc4i #ca #dd4g #cb #de4d #cc #df4a #cd #df4g #ce #dg4d #cf #dh4a #cg #dh4h #ch #di4e #ci #ej4a #dj #ej4g #da #ea4c #db #eb4j #dc #eb4f #dd #ec4b #de #ec4h #df #ed4d #dg #ee4j #dh #ee4f #di #ef4b #ej #ef4g #ee #ei4e #fj #fb4a #fe #fd4g #gj #fg4a #ge #fi4e #hj #ga4h #he #gd4j #ij #gf4a #ie #gh4b #ajj #hj4c #bjj #aad4j #cjj #aci4j #djj #afj4j #ejj #agi4j #ajjj #bed4j ,in the above example1 we found that #cgf cubic feet of water a minute1 under #ac4e feet head1 would deliver #g4b actual horsepower4 ,question3 ,what size wheel would it be necessary to install under such conditions8 ,by referring to the table of velocity above1 7or by using the formula71 we find that water under a head of #ac4e feet1 has a spouting velocity of #bi4e feet a second4 ,this means that a solid stream of water #bi4e feet long would pass through the wheel in one second4 ,what should be the diameter of such a stream1 to make its cubical contents #cgf cubic feet a minute or #cgf_/fj #f4bg cubic feet a second8 ,the following formula should be used to determine this3 #add cu4 ft4 per second 7,b7 ,sq4 ,inches of wheel -------------------------- ,velocity in ft4 per sec4 ,substituting values1 in the above instance1 we have3 ,answer3 ,sq4 ,inches of wheel #add #f4bg 7,cu4 ,ft4 ,sec47 --------------------------- #cj4f sq4 in4 #bi4e 7,vel4 in feet47 ,that is1 a wheel capable of using #cj4f square inches of water would meet these conditions4 ,what ,head is ,required ,let us attack the problem of water-power in another way4 ,a farmer wishes to install a water wheel that will deliver #aj horsepower on the shaft1 and he finds his stream delivers #djj cubic feet of water a minute4 ,how many feet fall is required8 ,formula3 #cc1jjj horsepower required 7,c7 ,head in feet ------------------------------ ,cu4 ,ft4 per minute #fb4e ,since a theoretical horsepower is only #ge per cent efficient1 he would require #aj #d_/c #ac4cc theoretical horsepower of water1 in this instance4 ,substituting the values of the problem in the formula1 we have3 #cc1jjj #ac4cc ,answer3 ,head ---------------- #ag4f feet fall required4 #djj #fb4e ,what capacity of wheel would this prospect 7#djj cubic feet of water a minute falling #ag4f feet1 and developing #ac4cc horsepower7 require8 ,by referring to the table of velocities1 we find that the velocity for #ag4e feet head 7nearly7 is #cc4f feet a second4 ,four hundred feet of water a minute is #djj_/fj #f4fg cu4 ft4 a second4 ,substituting these values1 in formula 7,b7 then1 we have3 ,answer3 ,capacity of wheel #add #f4fg ---------- #bh4f square inches of water4 #cc4f ,quantity of ,water ,let us take still another problem which the prospector may be called on to solve3 ,a man finds that he can conveniently get a fall of #bg feet4 ,he desires #bj actual horsepower4 ,what quantity of water will be necessary1 and what capacity wheel8 ,twenty actual horsepower will be #bj #d_/c #bf4fg theoretical horsepower4 ,formula3 #cc1jjj ,hp4 required 7,d7 ,cubic feet per minute --------------------- 7,head in feet #fb4e7 ,substituting values1 then1 we have3 ,cu4 ft4 per minute #cc1jjj #bf4fg -------------- #eba4e cubic feet a minute4 #bg #fb4e ,a head of #bg feet would give this stream a velocity of #da4g feet a second1 and1 from formula 7,b7 we find that the capacity of the wheel should be #cj square inches4 ,it is well to remember that the square inches of wheel capacity does not refer to the size of pipe conveying water from the head to the wheel1 but merely to the actual nozzle capacity provided by the wheel itself4 ,in small installations of low head1 such as above a penstock at least six times the nozzle capacity should be used1 to avoid losing effective head from friction4 ,thus1 with a nozzle of #cj square inches1 the penstock or pipe should be #ahj square inches1 or nearly #ad inches square inside measurement4 ,a larger penstock would be still better4 ,,chapter ,,iv ,,the ,,water ,,wheel ,,and ,,how ,,to ,,install ,,it ,different types of water wheels--,the impulse and reaction wheels--,the impulse wheel adapted to high heads and small amount of water--,pipe lines--,table of resistance in pipes--,advantages and disadvantages of the impulse wheel--,other forms of impulse wheels--,the reaction turbine1 suited to low heads and large quantity of water--,its advantages and limitations--,developing a water-power project3 the dam2 the race2 the flume2 the penstock2 and the tailrace--,water rights for the farmer4 ,in general1 there are two types of water wheels1 the impulse wheel and the reaction wheel4 ,both are called turbines1 although the name belongs1 more properly1 to the reaction wheel alone4 ,impulse wheels derive their power from the momentum of falling water4 ,reaction wheels derive their power from the momentum and pressure of falling water4 ,the old-fashioned undershot1 overshot1 and breast wheels are familiar to all as examples of impulse wheels4 ,water wheels of this class revolve in the air1 with the energy of the water exerted on one face of their buckets4 ,on the other hand1 reaction wheels are enclosed in water-tight cases1 either of metal or of wood1 and the buckets are entirely surrounded by water4 ,the old-fashioned undershot1 overshot1 and breast wheels were not very efficient2 they wasted about #ge per cent of the power applied to them4 ,a modern impulse wheel1 on the other hand1 operates at an efficiency of #hj per cent and over4 ,the loss is mainly through friction and leakage1 and cannot be eliminated altogether4 ,the modern reaction wheel1 called the turbine1 attains an equal efficiency4 ,individual conditions govern the type of wheel to be selected4 ,the ,impulse1 or ,tangential ,water ,wheel ,the modern impulse1 or tangential wheel 7so called because the driving stream of water strikes the wheel at a tangent7 is best adapted to situations where the amount of water is limited1 and the head is large4 ,thus1 a mountain brook supplying only seven cubic feet of water a minute--a stream less than two-and-a-half inches deep flowing over a weir with an opening three inches wide--would develop two actual horsepower1 under a head of #bjj feet--not an unusual head to be found in the hill country4 ,under a head of one thousand feet1 a stream furnishing #ceb4f cubic feet of water a minute would develop #ecd4ja horsepower at the nozzle4 ,ordinarily these wheels are not used under heads of less than #bj feet4 ,a wheel of this type1 six feet in diameter1 would develop six horsepower1 with #ahh cubic feet of water a minute and #bj-;foot head4 ,the great majority of impulse wheels are used under heads of #ajj feet and over4 ,in this country the greatest head in use is slightly over #b1ajj feet1 although in ,switzerland there is one plant utilizing a head of over #e1jjj feet4 ,illustration3 ,runner of ,pelton wheel1 showing peculiar shape of the buckets ,illustration3 ,the ,fitz overshoot wheel ,efficient ,modern ,adaptations of the ,archaic ,undershot and ,overshot ,water ,wheels ,the old-fashioned impulse wheels were inefficient because of the fact that their buckets were not constructed scientifically1 and much of the force of the water was lost at the moment of impact4 ,the impulse wheel of to-day1 however1 has buckets which so completely absorb the momentum of water issuing from a nozzle1 that the water falls into the tailrace with practically no velocity4 ,when it is remembered that the nozzle pressure under a #b1bej-;foot head is nearly #a1jjj pounds to the square inch1 and that water issues from this nozzle with a velocity of #bc1jjj feet a minute1 the scientific precision of this type of bucket can be appreciated4 ,a typical bucket for such a wheel is shaped like an open clam shell1 the central line which cuts the stream of water into halves being ground to a sharp edge4 ,the curves which absorb the momentum of the water are figured mathematically and in practice become polished like mirrors4 ,so great is the eroding action of water1 under great heads--especially when it contains sand or silt--that it is occasionally necessary to replace these buckets4 ,for this reason the larger wheels consist merely of a spider of iron or steel1 with each bucket bolted separately to its circumference1 so that it can be removed and replaced easily4 ,usually only one nozzle is provided2 but in order to use this wheel under low heads--down to #aj feet--a number of nozzles are used1 sometimes five1 where the water supply is plentiful4 ,the wheel is keyed to a horizontal shaft running in babbited bearings1 and this same shaft is used for driving the generator1 either by direct connection1 or by means of pulleys and a belt4 ,the wheel may be mounted on a home-made timber base1 or on an iron frame4 ,it takes up very little room1 especially when it is so set that the nozzle can be mounted under the flooring4 ,the wheel itself is enclosed1 above the floor1 in a wooden box1 or a casing made of cast or sheet iron1 which should be water-tight4 ,since these wheels are usually operated under great heads1 the problem of regulating their water supply requires special consideration4 ,a gate is always provided at the upper1 or intake end1 where the water pipe leaves the flume4 ,since the pressure reaches #a1jjj pounds the square inch and more1 there would be danger of bursting the pipe if the water were suddenly shut off at the nozzle itself4 ,for this reason it is necessary to use a needle valve1 similar to that in an ordinary garden hose nozzle2 and by such a valve the amount of water may be regulated to a nicety4 ,where the head is so great that even such a valve could not be used safely1 provision is made to deflect the nozzle4 ,these wheels have a speed variation amounting to as much as #be per cent from no-load to full load1 in generating electricity1 and since the speed of the prime mover--the water wheel--is reflected directly in the voltage or pressure of electricity delivered1 the wheel must be provided with some form of automatic governor4 ,this consists usually of two centrifugal balls1 similar to those used in governing steam engines2 these are connected by means of gears to the needle valve or the deflector4 ,as the demand for farm water-powers in our hill sections becomes more general1 the tangential type of water wheel will come into common use for small plants4 ,at present it is most familiar in the great commercial installations of the ,far ,west1 working under enormous heads4 ,these wheels are to be had in the market ranging in size from six inches to six feet and over4 ,wheels ranging in size from six inches to twenty-four inches are called water motors1 and are to be had in the market1 new1 for #cj for the smallest size1 and #bge for the largest4 ,above three feet in diameter1 the list prices will run from #bjj for a #c-;foot wheel to #hjj for a #f-;foot wheel4 ,where one has a surplus of water1 it is possible to install a multiple nozzle wheel1 under heads of from #aj to #ajj feet1 the cost for #ah-;inch wheels of this pattern running from #aej to #ahj list1 and for #bd-;inch wheels from #bjj to #bej4 ,a #bd-;inch wheel1 with a #aj-;foot head would give #a4ai horsepower1 enough for lighting the home1 and using an electric iron4 ,under a #ajj-;foot head this same wheel would provide #be4i horsepower1 to meet the requirements of a bigger-than-average farm plant4 ,the ,pipe ,line ,the principal items of cost in installing an impulse wheel are in connection with the pipe line1 and the governor4 ,in small heads1 that is1 under #ajj feet1 the expense of pipe line is low4 ,frequently1 however1 the governor will cost more than the water motor itself1 although cheaper1 yet efficient1 makes are now being put on the market to meet this objection4 ,in a later chapter1 we will take up in detail the question of governing the water wheel1 and voltage regulation1 and will attempt to show how this expense may be practically eliminated by the farmer4 ,to secure large heads1 it is usually necessary to run a pipe line many hundreds 7and in many cases1 many thousands7 of feet from the flume to the water wheel4 ,water flowing through pipes is subject to loss of head1 by friction1 and for this reason the larger the pipe the less the friction loss4 ,under no circumstances is it recommended to use a pipe of less than two inches in diameter1 even for the smallest water motors2 and with a two-inch pipe1 the run should not exceed #bjj feet4 ,where heavy-pressure mains1 such as those of municipal or commercial water systems1 are available1 the problem of both water supply and head becomes very simple4 ,merely ascertain the pressure of the water in the mains when flowing1 determine the amount of power required 7as illustrated in a succeeding chapter of this book71 and install the proper water motor with a suitably sized pipe4 ,where one has his own water supply1 however1 and it is necessary to lay pipe to secure the requisite fall1 the problem is more difficult4 ,friction in pipes acts in the same way as cutting down the head a proportional amount2 and by cutting down the head1 your water motor loses power in direct proportion to the number of feet head lost4 ,this head1 obtained by subtracting friction and other losses from the surveyed head1 is called the effective head1 and determines the amount of power delivered at the nozzle4 ,the tables on pages #ff-fg show the friction loss in pipes up to #ab inches in diameter1 according to the amount of water1 and the length of pipe4 ,in this example it is seen that a #bdj-;foot static head is reduced by friction to #bcj4a feet effective head4 ,by referring to the table we find the wheel fitting these conditions has a nozzle so small that it cuts down the rate of flow of water in the big pipe to #d4d feet a second1 and permits the flow of only #bjg cubic feet of water a minute4 ,the actual horsepower of this tube and nozzle1 then1 can be figured by applying formula 7,a71 ,chapter ,,iii1 allowing #hj per cent for the efficiency of the wheel4 ,thus3 ,actual horsepower #bjg #bcj4a #fb4e ------------------ #ij4ba 4#hj #gb4afh ,hp4 #cc1jjj ,to calculate what the horsepower of this tube #ab inches in diameter and #ijj feet long1 would be without a nozzle1 under a head of #bdj feet1 introduces a new element of friction losses1 which is too complicated to figure here4 ,such a condition would not be met with in actual practice1 in any event4 ,the largest nozzles used1 even in the jumbo plants of the ,far ,west1 rarely exceed #aj inches in diameter2 and the pipe conveying water to such a nozzle is upwards of eight feet in diameter4 ,,pipe ,,friction ,,tables ,,indicating ,,the ,,calculated ,,loss ,,of ,,head ,,due ,,to ,,friction ,,in ,,riveted ,,steel ,,pipe ,,with ,,various ,,water ,,quantities ,,and ,,velocities ,courtesy of the ,pelton ,water ,wheel ,company ,heavy-faced figures ,loss of head in feet for each one thousand feet of pipe4 ,light-faced figures ,water quantity in cubic feet per minute4 ---------------------------------------- ---------------------------------------- ------------------- ,pipe ,velocity in ,feet per ,second ,diameter------------------------------- ---------------------------------------- -------- #b4j #b4b #b4d #b4f #b4h #c4j #c4b #c4d #c4f #c4h #d4j #d4b #d4d ---------------------------------------- ---------------------------------------- ------- #ag4abj4jbe4fbh4ccb4jcg4cdj4ide4hej4def4 jfb4cfh4agd4i #c #e4i #f4e #g4a #g4g #h4c #h4i #i4d #aj4j #aj4f #aa4b #aa4h #ab4d #ac4j #aa4jac4jae4jag4cbj4bbc4bbf4bbi4fcc4jcf4 eda4jde4ddi4b #d #aj4e #aa4e #ab4f #ac4f #ad4g #ae4g #af4h #ag4h #ah4h #ai4i #ba4j #bb4j #bc4j #g4g #i4daa4jab4iad4iaf4iai4eba4fbd4jbg4jbi4h cb4icf4j #e #af4d #ah4j #ai4f #ba4b #bb4i #bd4e #bf4a #bg4h #bi4e #ca4j #cb4g #cd4c #cf4j #f4j #g4b #h4f #i4iaa4gac4jad4faf4fai4jba4ebc4dbe4ebg4h #f #bc4e #be4i #bh4b #cj4f #cb4i #ce4c #cg4g #dj4j #db4d #dd4g #dg4a #di4e #ea4h #d4i #f4i #g4j #h4a #i4caj4fab4jac4fae4bag4jai4jba4jbc4j #g #cb4j #ce4c #ch4e #da4g #dd4i #dh4a #ea4c #ed4e #eg4g #fj4i #fd4a #fg4c #gj4e #d4j #d4i #f4j #f4i #g4h #i4aaj4jaj4bac4jad4dae4iag4bai4b #h #da4i #df4a #ej4b #ed4d #eh4f #fb4h #fg4j #ga4b #ge4d #gi4f #hc4g #hg4i #ib4a #c4d #d4b #e4a #e4i #f4g #g4g #h4i #i4haa4jab4bac4hae4jaf4j #i #ec4j #eh4c #fc4f #fh4i #gd4b #gi4e #hd4h #ij4a #ie4d #aja #ajf #aaa #aaf #b4i #c4g #d4d #e4a #e4i #f4g #g4e #h4f #i4eaj4fab4aac4aad4a #aj #fe4d #gb4j #gh4e #he4a #ia4f #ih4b #aje #aaa #aah #abd #aca #acg #add #b4f #c4b #c4h #d4d #e4a #e4i #f4f #g4e #h4d #i4eaj4caj4aab4e #aa #gi #hg #ie #ajc #aaa #aai #abg #acd #adb #aej #aeh #aff #agd #b4cf #b4i #c4d #c4i #d4e #e4b #e4i #f4g #g4e #h4e #i4daj4jaa4j #ab #id #ajc #aac #abb #acb #ada #aea #afj #afi #agi #ahh #aih #bjg ---------------------------------------- ---------------------------------------- ------- ---------------------------------------- ---------------------------------------- -------- #d4f #d4h #e4j #e4b #e4d #e4f #e4h #f4j #g4j #h4j #i4j #aj4j ---------------------------------------- ---------------------------------------- -------- #gh4ahb4jhi4eih4iaje4jaac4babj4hacj4jafb 4hbaf4jbgj4 #cbc4 #c #ac4f #ad4b #ad4h #ae4c #ae4i #af4e #ag4a #ag4g #bj4f #bc4e #bf4e #bi4e #eb4ceg4jfa4efh4j #gb4e #gh4b #hc4a #hi4eaba4 #aee4 #aih4 #bdb4 #d #bd4a #be4a #bf4b #bg4b #bh4c #bi4c #cj4d #ca4e #cf4f #da4i #dg4b #eb4d #ci4bdb4cdf4jdi4h #ec4e #eh4j #fb4j #fg4j #hi4 #aah4 #adh4 #ahb4 #e #cg4f #ci4b #dj4i #db4e #dd4a #de4h #dg4e #di4a #eg4a #fe4d #gc4g #hb4j #cj4fcc4ace4fci4j #da4f #dd4f #dh4j #ea4f #fi4j #hi4jaad4 #adj4 #f #ed4a #ef4e #eh4i #fa4b #fc4f #fe4i #fh4c #gj4g #hb4d #id4c #ajf #aah #be4abg4cbi4ecb4j #cd4e #cg4a #dj4j #dc4j #eh4j #ge4j #ie4jaaf4 #g #gc4g #gf4i #hj4b #hc4c #hf4f #hi4h #ic4j #if4b #aab #abh #ade #afa #bj4jbb4ebd4ibg4j #bh4h #cj4f #cb4h #ce4e #dg4e #fa4b #gh4f #ie4a #h #if4c #aja #aje #aji #aac #aag #aba #abe #adf #afh #ahi #baj #ag4aai4bba4jbb4i #bd4f #bf4b #bh4j #cj4a #dj4a #eb4a #ff4f #hb4j #i #abb #abg #acb #ach #adc #adh #aed #aei #ahe #bab #bch #bfe #ad4haf4gag4iai4i #ba4j #bb4g #bd4c #be4i #cd4h #de4i #eh4j #gj4a #aj #aej #aeg #afc #agj #agg #ahc #aij #aif #bbi #bfa #bie #cbg #ac4jad4gae4iag4a #ah4b #bj4a #ba4c #bb4f #cj4g #dj4j #ej4h #fb4j #aa #ahb #aij #aih #bjf #bad #bbb #bbi #bcg #bgg #caf #cef #cif #aa4fac4jad4jae4a #af4a #ag4h #ai4a #bj4b #bg4a #ce4i #de4d #ee4i #ab #bag #bbf #bce #bde #bed #bfd #bgc #bhc #ccj #cgg #dbe #dgb ---------------------------------------- ---------------------------------------- --------- ,,example ,assume the surveyed head as #bdj feet1 the water quantity as #bjg cubic feet per minute and a pipe line #ab inches in diameter #ijj feet long4 ,to ascertain the friction loss1 refer to column of pipe diameter and follow across the column for #ab inches diameter to the quantity1 #bjg cubic feet per minute4 ,the heavy-faced figures above #bjg indicate that the loss per #ajjj feet of pipe length is #aa feet4 ,therefore1 since the pipe in the example is #ijj feet long1 the loss will be #aa4' #ijj_/ajjj or #i4i feet1 and the effective head will be #bdj' - #i4i' #bcj4a' ,steel tubing for supply pipes1 from #c to #ab inches in diameter is listed at from #bj cents to #a4ej a foot1 according to the diameter and thickness of the material4 ,discounts on these prices will vary from #be to #ej per cent4 ,the farmer can cut down the cost of this pipe by conveying his supply water from its natural source to a pond1 by means of an open race1 or a wooden flume4 ,an ingenious mechanic can even construct his own pipe out of wood1 though figuring labor and materials1 it is doubtful if anything would be saved over a riveted steel pipe1 purchased at the regular price4 ,this pipe1 leading from the pond1 or forebay1 to the water wheel1 should be kept as short as possible2 at the same time1 the fall should not be too sharp4 ,an angle of #cj will be found very satisfactory1 although pipe is frequently laid at angles up to #ej4 ,other ,types of ,impulse ,wheels ,in recent years more efficient forms of the old-fashioned overshoot1 pitch-back breast1 and undershoot wheels have been developed1 by substituting steel or other metal for wood1 and altering the shape of the buckets to make better use of the power of falling water4 ,in some forms of overshoot wheels1 an efficiency of over #ij per cent is claimed by manufacturers2 and this type offers the additional advantage of utilizing small quantities of water1 as well as being efficient under varying quantities of water4 ,they utilize the falling weight of water1 although by giving the water momentum at the point of delivery1 by means of the proper fall1 impulse too is utilized in some measure4 ,the modern steel overshoot wheel receives water in its buckets from a spout set a few degrees back of dead center2 and its buckets are so shaped that the water is retained a full half-revolution of the wheel4 ,the old-style overshoot wheel was inefficient principally because the buckets began emptying themselves at the end of a quarter-revolution4 ,another advantage claimed for these wheels over the old style is that1 being made of thin metal1 their buckets attain the temperature of the water itself1 thus reducing the danger of freezing to a minimum4 ,they are manufactured in sizes from #f feet in diameter to upwards of fifty feet2 and with buckets of from #f inches to #aj feet in width4 ,in practice it is usual to deliver water to the buckets by means of a trough or pipe1 through a suitable spout and gate1 at a point two feet above the crown of the wheel4 ,for this reason1 the diameter of the wheel corresponds very closely to the head in feet4 ,the ,reaction ,turbine ,the reaction turbine is best adapted to low heads1 with a large supply of water4 ,it is not advisable1 under ordinary circumstances1 to use it under heads exceeding #ajj feet1 as its speed is then excessive4 ,it may be used under falls as low as two feet4 ,five thousand cubic feet of water a minute would give approximately #ad actual horsepower under such a head4 ,a sluggish creek that flows in large volume could thus be utilized for power with the reaction turbine1 whereas it would be useless with an impulse wheel4 ,falls of from five to fifteen feet are to be found on thousands of farm streams1 and the reaction turbine is admirably adapted to them4 ,reaction turbines consist of an iron runner which is in effect a rotary fan1 the pressure and momentum of the column of water pressing on the slanted blades giving it motion and power4 ,these wheels are manufactured in a great variety of forms and sizes2 and are to be purchased either as the runner 7set in bearings7 alone1 or as a runner enclosed in an iron case4 ,in case the runner alone is purchased1 the owner must enclose it1 either with iron or wood4 ,they vary in price according to size1 and the means by which the flow of water is controlled4 ,a simple #ab-;inch reaction turbine wheel1 such as would be suitable for many power plants can be had for #ge4 ,a twelve-inch wheel1 using #ah or #bj square inches of water1 would generate about #g-a_/b horsepower under a #bj-;foot head1 with #bfh cubic feet of water a minute4 ,under a #cj-;foot head1 and with #ccj cubic feet of water such a wheel will give #ad horsepower4 ,a #cf-;inch wheel1 under a #e-;foot head1 would use #b1jjj cubic feet of water1 and give #ad horsepower4 ,under a #cj-;foot head1 this same wheel1 using #d1ijj cubic feet of water a minute1 would develop over #bjj horsepower4 ,if the farmer is confronted by the situation of a great deal of water and small head1 a large wheel would be necessary4 ,thus he could secure #ce horsepower with only a #c-;foot head1 providing his water supply is equal to the draft of #h1cjj cubic feet a minute4 ,from these sample figures1 it will be seen that the reaction turbine will meet the requirements of widely varying conditions up to1 say a head of #ajj feet4 ,the farmer prospector should measure first the quantity of water to be depended on1 and then the number of feet fall to be had4 ,the higher the fall1 with certain limits1 the smaller the expense of installation1 and the less water required4 ,when he has determined quantity and head1 the catalogue of a reputable manufacturer will supply him with what information is necessary to decide on the style and size wheel he should install4 ,in the older settled communities1 especially in ,new ,england1 a farmer should be able to pick up a second-hand turbine1 at half the price asked for a new one2 and since these wheels do not depreciate rapidly1 it would serve his purpose as well1 in most cases1 as a new one4 ,illustration3 ,a typical vertical turbine ,reaction turbines may be either horizontal or vertical4 ,if they are vertical1 it is necessary to connect them to the main shaft by means of a set of bevel gears4 ,these gears should be substantially large1 and if the teeth are of hard wood 7set in such a manner that they can be replaced when worn7 they will be found more satisfactory than if of cast or cut metal4 ,illustration3 ,two wheels on a horizontal shaft 7,courtesy of the ,c4 ,p4 ,bradway ,company1 ,west ,stafford1 ,conn47 ,the horizontal turbine is keyed to its shaft1 like the impulse wheel1 so that the wheel shaft itself is used for driving1 without gears or a quarter-turn belt4 7,the latter is to be avoided1 wherever possible47 ,there are many forms of horizontal turbines2 they are to be had of the duplex type1 that is1 two wheels on one shaft4 ,these are arranged so that either wheel may be run separately1 or both together1 thus permitting one to take advantage of the seasonal fluctuation in water supply4 ,a convenient form of these wheels includes draft tubes1 by which the wheel may be set several feet above the tailrace1 and the advantage of this additional fall still be preserved4 ,in this case the draft tube must be airtight so as to form suction1 when filled with escaping water1 and should be proportioned to the size of the wheel4 ,theoretically these draft tubes might be #cd feet long1 but in practice it has been found that they should not exceed #aj or #ab feet under ordinary circumstances4 ,they permit the wheel to be installed on the main floor of the power station1 with the escape below1 instead of being set just above the tailrace level itself1 as is the case when draft tubes are not used4 ,reaction turbines when working under a variable load require water governors 7like impulse wheels7 although where the supply of water is large1 and the proportion of power between water wheel and dynamo is liberal--say two to one1 or more--this necessity is greatly reduced4 ,reaction wheels as a rule govern themselves better than impulse wheels1 due both to the fact that they use more water1 and that they operate in a small airtight case4 ,the centrifugal ball governor is the type usually used with reaction wheels as well as with impulse wheels4 ,this subject will be discussed more fully later4 ,installing a ,power ,plant ,in developing a power prospect1 the dam itself is usually not the site of the power plant4 ,in fact1 because of danger from flood water and ice1 it is better to locate it in a more protected spot1 leading the water to the wheel by means of a race and flume4 ,illustration3 ,bird's-eye view of a developed water-power plant ,a typical crib dam1 filled with stone1 is shown in section in the diagram1 and the half-tone illustration shows such a dam in course of construction4 ,the first bed of timbers should be laid on hard-pan or solid rock in the bed of the stream parallel to its flow4 ,the second course1 across the stream1 is then begun1 being spiked home by means of rods cut to length and sharpened by the local blacksmith1 from #c_/d-;inch ,norway iron4 ,hemlock logs are suitable for building the crib2 and as the timbers are finally laid1 it should be filled in and made solid with boulders4 ,this filling in should proceed section by section1 as the planking goes forward1 otherwise there will be no escape for the water of the stream1 until it rises and spills over the top timbers4 ,the planking should be of two-inch chestnut1 spiked home with #fj penny wire spikes4 ,when the last section of the crib is filled with boulders and the water rises1 the remaining planks may be spiked home with the aid of an iron pipe in which to drive the spike by means of a plunger of iron long enough to reach above the level of the water4 ,when the planking is completed1 the dam should be well gravelled1 to within a foot or two of its crest4 ,such dams are substantial1 easily made with the aid of unskilled labor1 and the materials are to be had on the average farm with the exception of the hardware4 ,illustration3 ,cross-section of a rock and timber dam ,this dam forms a pond from which the race draws its supply of water for the wheel4 ,it also serves as a spillway over which the surplus water escapes4 ,the race should enter the pond at some convenient point1 and should be protected at or near its point of entrance by a bulkhead containing a gate1 so that the supply of water may be cut off from the race and wheel readily4 ,the lay of the land will determine the length and course of the race4 ,the object of the race is to secure the required head by carrying a portion of the available water to a point where it can escape1 by a fall of say #cj to the tailrace4 ,it may be feasible to carry the race in a line almost at right angles to the stream itself1 or1 again1 it may be necessary to parallel the stream4 ,if the lay of the land is favorable1 the race may be dug to a distance of a rod or so inshore1 and then be permitted to cut its own course along the bank1 preventing the water escaping back to the river or brook before the site of the power plant is reached1 by building suitable retaining embankments4 ,the race should be of ample size for conveying the water required without too much friction4 ,it should end in a flume constructed stoutly of timbers4 ,it is from this flume that the penstock draws water for the wheel4 ,when the wheel gate is closed the water in the mill pond behind the dam1 and in the flume itself should maintain an approximate level4 ,any surplus flow is permitted to escape over flushboards in the flume2 these same flushboards maintain a constant head when the wheel is in operation by carrying off what little surplus water the race delivers from the pond4 ,illustration3 ,detail of bulkhead gate ,at some point in the race or flume1 the flow should be protected from leaves and other trash by means of a rack4 ,this rack is best made of #a_/d or #a_/b-;inch battens from #a-a_/b to #c inches in width1 bolted together on their flat faces and separated a distance equal to the thickness of the battens by means of iron washers4 ,this rack will accumulate leaves and trash1 varying with the time of year and should be kept clean1 so as not to cut down the supply of water needed by the wheel4 ,the penstock1 or pipe conveying water from the flume to the wheel1 should be constructed of liberal size1 and substantially1 of two-inch chestnut planking1 with joints caulked with oakum1 and the whole well bound together to resist the pressure of the water4 ,means should be provided near the bottom for an opening through which to remove any obstructions that may by accident pass by the rack4 ,many wheels have plates provided in their cases for this purpose4 ,the tailrace should be provided with enough fall to carry the escaping water back to the main stream1 without backing up on the wheel itself and thus cutting down the head4 ,it is impossible to make any estimates of the cost of such a water-power plant4 ,the labor required will in most instances be supplied by the farmer himself1 his sons1 and his help1 during times when farm operations are slack4 ,water ,rights of the ,farmer ,the farmer owns the bed of every stream not navigable1 lying within the boundary lines of the farm2 and his right to divert and make use of the water of such streams is determined in most states by common law4 ,in the dry-land states where water is scarce and is valuable for irrigation1 a special set of statutes has sprung up with the development of irrigation in this country4 ,a stream on the farm is either public or private2 its being navigable or floatable 7suitable for floating logs7 determining which4 ,water rights are termed in law riparian rights1 and land is riparian only when water flows over it or along its borders4 ,green 7,law for the ,american ,farmer7 says3 ,water is the common and equal property of every one through whose land it flows1 and the right of each land-owner to use and consume it without destroying1 or unreasonably impairing the rights of others1 is the same4 ,an owner of land bordering on a running stream has the right to have its waters flow naturally1 and none can lawfully divert them without his consent4 ,each riparian proprietor has an equal right with all the others to have the stream flow in its natural way without substantial reduction in volume1 or deterioration in quality1 subject to a proper and reasonable use of its waters for domestic1 agricultural and manufacturing purposes1 and he is entitled to use it himself for such purposes1 but in doing so must not substantially injure others4 ,in addition to the right of drawing water for the purposes just mentioned1 a riparian proprietor1 if he duly regards the rights of others1 and does not unreasonably deplete the supply1 has also the right to take the water for some other proper uses4 ,thus1 the farmer who seeks to develop water-power from a stream flowing across his own land1 has the right to divert such a stream from its natural channel--providing it is not a navigable or floatable stream--but in so doing1 he must return it to its own channel for lower riparian owners4 ,the generation of water-power does not pollute the water1 nor does it diminish the water in quantity1 therefore the farmer is infringing on no other owner's rights in using the water for such a purpose4 ,when a stream is a dividing line between two farms1 as is frequently the case1 each proprietor owns to the middle of the stream and controls its banks4 ,therefore to erect a dam across such a private stream and divert all or a part of the water for power purposes1 requires the consent of the neighboring owner4 ,the owner of the dam is responsible for damage due to flooding1 to upstream riparian owners4 ,,part ,,ii ,,electricity ,,chapter ,v ,,the ,,dynamo2 ,,what ,,it ,,does1 ,,and ,,how ,electricity compared to the heat and light of the ,sun--,the simple dynamo--,the amount of electric energy a dynamo will generate--,the modern dynamo--,measuring power in terms of electricity--,the volt--,the ampere--,the ohm--,the watt and the kilowatt--,ohm's ,law of the electric circuit1 and some examples of its application--,direct current1 and alternating current--,three types of direct-current dynamos3 series1 shunt1 and compound4 ,what a farmer really does in generating electricity from water that would otherwise run to waste in his brook1 is to install a private ,sun of his own--which is on duty not merely in daylight1 but twenty-four hours a day2 a private ,sun which is under such simple control that it shines or provides heat and power1 when and where wanted1 simply by touching a button4 ,this is not a mere fanciful statement4 ,when you come to look into it you find that electricity actually is the life-giving power of the ,sun's rays1 so transformed that it can be handily conveyed from place to place by means of wires1 and controlled by mechanical devices as simple as the spigot that drains a cask4 ,nature has the habit of traveling in circles4 ,sometimes these circles are so big that the part of them we see looks like a straight line1 but it is not4 ,even parallel lines1 according to the mathematicians1 meet in infinity4 ,take the instance of the water wheel which the farmer has installed under the fall of his brook4 ,the power which turns the wheel has the strength of many horses4 ,it is there in a handy place for use1 because the ,sun brought it there4 ,the ,sun1 by its heat1 lifted the water from sea-level1 to the pond where we find it--and we cannot get any more power out of this water by means of a turbine using its pressure and momentum in falling1 than the ,sun itself expended in raising the water against the force of gravity4 ,once we have installed the wheel to change the energy of falling water into mechanical power1 the task of the dynamo is to turn this mechanical power into another mode of motion--electricity4 ,and the task of electricity is to change this mode of motion back into the original heat and light of the ,sun--which started the circle in the beginning4 ,astronomers refer to the ,sun as he and him and they spell his name with a capital letter1 to show that he occupies the center of our small neighborhood of the universe at all times4 ,magnets and ,magnetism ,the dynamo is a mechanical engine1 like the steam engine1 the water turbine or the gas engine2 and it converts the mechanical motion of the driven wheel into electrical motion1 with the aid of a magnet4 ,many scientists say that the full circle of energy that keeps the world spinning1 grows crops1 and paints the sky with the ,aurora ,borealis1 begins and ends with magnetism--that the sun's rays are magnetic rays4 ,magnetism is the force that keeps the compass needle pointing north and south4 ,take a steel rod and hold it along the north and south line1 slightly inclined towards the earth1 and strike it a sharp blow with a hammer1 and it becomes a magnet--feeble1 it is true1 but still a magnet4 ,take a wire connected with a common dry battery and hold a compass needle under it and the needle will immediately turn around and point directly across the wire1 showing that the wire possesses magnetism encircling it in invisible lines1 stronger than the magnetism of the earth4 ,illustration3 7,courtesy of the ,crocker-,wheeler ,company7 ,a direct-current dynamo or motor1 showing details of construction ,insulate this wire by covering it with cotton thread1 and wind it closely on a spool4 ,connect the two loose ends to a dry battery1 and you will find that you have multiplied the magnetic strength of a single loop of wire by the number of turns on the spool--concentrated all the magnetism of the length of that wire into a small space4 ,put an iron core in the middle of this spool and the magnet seems still more powerful4 ,lines of force which otherwise would escape in great circles into space1 are now concentrated in the iron4 ,the iron core is a magnet4 ,shut off the current from the battery and the iron is still a magnet--weak1 true1 but it will always retain a small portion of its magnetism4 ,soft iron retains very little of its magnetism4 ,hard steel retains a great deal1 and for this reason steel is used for permanent magnets1 of the horseshoe type so familiar4 ,a ,simple ,dynamo ,a dynamo consists1 first1 of a number of such magnets1 wound with insulated wire4 ,their iron cores point towards the center of a circle like the spokes of a wheel2 and their curved inner faces form a circle in which a spool1 wound with wire in another way1 may be spun by the water wheel4 ,now take a piece of copper wire and make a loop of it4 ,pass one side of this loop in front of an electric magnet4 ,as the wire you hold in your hands passes the iron face of the magnet1 a wave of energy that is called electricity flows around this loop at the rate of #ahf1jjj miles a second--the same speed as light comes to us from the sun4 ,as you move the wire away from the magnet1 a second wave starts through the wire1 flowing in the opposite direction4 ,you can prove this by holding a compass needle under the wire and see it wag first in one direction1 then in another4 ,illustration3 ,a wire cutting the lines of force of an electro-magnet ,this is a simple dynamo4 ,a wire cutting the invisible lines of force1 that a magnet is spraying out into the air1 becomes electrified4 ,why this is true1 no one has ever been able to explain4 ,the amount of electricity--its capacity for work--which you have generated with the magnet and wire1 does not depend alone on the pulling power of that simple magnet4 ,let us say the magnet is very weak--has not enough power to lift one ounce of iron4 ,nevertheless1 if you possessed the strength of ,hercules1 and could pass that wire through the field of force of the magnet many thousands of times a second1 you would generate enough electricity in the wire to cause the wire to melt in your hands from heat4 ,illustration3 ,cross-section of an armature revolving in its field ,illustration3 ,forms of annealed steel discs used in armature construction ,this experiment gives the theory of the dynamo4 ,instead of passing only one wire through the field of force of a magnet1 we have hundreds bound lengthwise on a revolving drum called an armature4 ,instead of one magnetic pole in a dynamo we have two1 or four1 or twenty according to the work the machine is designed for--always in pairs1 a ,north pole next to a ,south pole1 so that the lines of force may flow out of one and into another1 instead of escaping in the surrounding air4 ,if you could see these lines of force1 they would appear in countless numbers issuing from each pole face of the field magnets1 pressing against the revolving drum like hair brush bristles--trying to hold it back4 ,this drum1 in practice1 is built up of discs of annealed steel1 and the wires extending lengthwise on its face are held in place by slots to prevent them from flying off when the drum is whirled at high speed4 ,the drum does not touch the face of the magnets1 but revolves in an air space4 ,if we give the electric impulses generated in these wires a chance to flow in a circuit--flow out of one end of the wires1 and in at the other1 the drum will require more and more power to turn it1 in proportion to the amount of electricity we permit to flow4 ,thus1 if one electric light is turned on1 the drum will press back with a certain strength on the water wheel2 if one hundred lights are turned on it will press back one hundred times as much4 ,providing there is enough power in the water wheel to continue turning the drum at its predetermined speed1 the dynamo will keep on giving more and more electricity if asked to1 until it finally destroys itself by fire4 ,you cannot take more power1 in terms of electricity1 out of a dynamo that you put into it1 in terms of mechanical motion4 ,in fact1 to insure flexibility and constant speed at all loads1 it is customary to provide twice as much water wheel1 or engine1 power as the electrical rating of the dynamo4 ,illustration3 ,an armature partly wound1 showing slots and commutator ,we have seen that a water wheel is #he per cent efficient under ideal conditions4 ,a dynamo's efficiency in translating mechanical motion into electricity1 varies with the type of machine and its size4 ,the largest machines attain as high as #ij per cent efficiency2 the smallest ones run as low as #dj per cent4 ,measuring ,electric ,power ,the amount of electricity any given dynamo can generate depends1 generally speaking1 on two factors1 i4 e41 7#a7 the power of the water wheel1 or other mechanical engine that turns the armature2 and 7#b7 the size 7carrying capacity7 of the wires on this drum4 ,strength1 of electricity1 is measured in amperes4 ,an ampere of electricity is the unit of the rate of flow and may be likened to a gallon of water per minute4 ,in surveying for water-power1 in ,chapter ,,iii1 we found that the number of gallons or cubic feet of water alone did not determine the amount of power4 ,we found that the number of gallons or cubic feet multiplied by the distance in feet it falls in a given time1 was the determining factor--pounds 7quantity7 multiplied by feet per second--7velocity74 ,illustration3 ,showing the analogy of water to volts and amperes of electricity ,the same is true in figuring the power of electricity4 ,we multiply the amperes by the number of electric impulses that are created in the wire in the course of one second4 ,the unit of velocity1 or pressure of the electric current is called a volt4 ,voltage is the pressure which causes electricity to flow4 ,a volt may be likened to the velocity in feet per second of water in falling past a certain point4 ,if you think a moment you will see that this has nothing to do with quantity4 ,a pin-hole stream of water under #dj pounds pressure has the same velocity as water coming from a nozzle as big as a barrel1 under the same pressure4 ,so with electricity under the pressure of one volt or one hundred volts4 ,one volt is said to consist of a succession of impulses caused by one wire cutting #ajj1jjj1jjj lines of magnetic force in one second4 ,thus1 if the strength of a magnet consisted of one line of force1 to create the pressure of one volt we would have to cut that line of force #ajj1jjj1jjj times a second1 with one wire2 or #ajj1jjj times a second with one thousand wires4 ,or1 if a magnet could be made with #ajj1jjj1jjj lines of force1 a single wire cutting those lines once in a second would create one volt pressure4 ,in actual practice1 field magnets of dynamos are worked at densities up to and over #ajj1jjj lines of force to the square inch1 and armatures contain several hundred conductors to cut these magnetic lines4 ,the voltage then depends on the speed at which the armature is driven4 ,in machines for isolated plants1 it will be found that the speed varies from #djj revolutions per minute1 to #a1hjj1 according to the design of dynamo used4 ,illustration3 ,pressure determines volume of flow in a given time ,multiplying amperes 7strength7 by volts 7pressure71 gives us watts 7power74 ,seven hundred and forty-six watts of electrical energy is equal to one horsepower of mechanical energy--will do the same work4 ,thus an electric current under a pressure of #ajj volts1 and a density of #g4df amperes1 is one horsepower2 as is #gd4f amperes1 at #aj volts pressure2 or #gdf amperes at one volt pressure4 ,for convenience 7as a watt is a small quantity7 electricity is measured in kilowatts1 or #a1jjj watts4 ,since #gdf watts is one horsepower1 #a1jjj watts or one kilowatt is #a4cd horsepower4 ,the work of such a current for one hour is called a kilowatt-hour1 and in our cities1 where electricity is generated from steam1 the retail price of a kilowatt-hour varies from #aj to #ae cents4 ,now as to how electricity may be controlled1 so that a dynamo will not burn itself up when it begins to generate4 ,again we come back to the analogy of water4 ,the amount of water that passes through a pipe in any given time1 depends on the size of the pipe1 if the pressure is maintained uniform4 ,in other words the resistance of the pipe to the flow of water determines the amount4 ,if the pipe be the size of a pin-hole1 a very small amount of water will escape4 ,if the pipe is as big around as a barrel1 a large amount will force its way through4 ,so with electricity4 ,resistance1 introduced in the electric circuit1 controls the amount of current that flows4 ,a wire as fine as a hair will permit only a small quantity to pass1 under a given pressure4 ,a wire as big as one's thumb will permit a correspondingly greater quantity to pass1 the pressure remaining the same4 ,the unit of electrical resistance is called the ohm--named after a man1 as are all electrical units4 ,ohm's ,law ,the ohm is that amount of resistance that will permit the passage of one ampere1 under the pressure of one volt4 ,it would take two volts to force two amperes through one ohm2 or #ajj volts to force #ajj amperes through the resistance of one ohm4 ,from this we have ,ohm's ,law1 a simple formula which is the beginning and end of all electric computations the farmer will have to make in installing his water-power electric plant4 ,ohm's ,law tells us that the density of current 7amperes7 that can pass through a given resistance in ohms 7a wire1 a lamp1 or an electric stove7 equals volts divided by ohms--or pressure divided by resistance4 ,this formula may be written in three ways1 thus3 ,c ,e_/,r1 or ,r ,e_/,c or1 ,e ,c ,r4 ,or to express the same thing in words1 current equals volts divided by ohms2 ohms equals volts divided by current2 or volts equals current multiplied by ohms4 ,so1 with any two of these three determining factors known1 we can find the third4 ,as we have said1 this simple law is the beginning and end of ordinary calculations as to electric current1 and it should be thoroughly understood by any farmer who essays to be his own electrical engineer4 ,once understood and applied1 the problem of the control of the electric current becomes simple a b c4 ,examples of ,ohm's ,law ,let us illustrate its application by an example4 ,the water wheel is started and is spinning the dynamo at its rated speed1 say #a1ejj r4p4m4 ,two heavy wires1 leading from brushes which collect electricity from the revolving armature1 are led1 by suitable insulated supports to the switchboard1 and fastened there4 ,they do not touch each other4 ,dynamo mains must not be permitted to touch each other under any conditions4 ,they are separated by say four inches of air4 ,dry air is a very poor conductor of electricity4 ,let us say1 for the example1 that dry air has a resistance to the flow of an electric current1 of #a1jjj1jjj ohms to the inch--that would be #d1jjj1jjj ohms4 ,how much electricity is being permitted to escape from the armature of this #aaj-volt dynamo1 when the mains are separated by four inches of dry air8 ,apply ,ohm's law1 ,c equals ,e divided by ,r4 ,e1 in this case is #aaj2 ,r is #d1jjj1jjj2 therefore ,c 7amperes7 equals #aaj_/d1jjj1jjj--;an infinitesimal amount--about 4#jjjjbgg ampere4 ,let us say that instead of separating these two mains by air we separated them by the human body--that a man took hold of the bare wires1 one in each hand4 ,the resistance of the human body varies from #e1jjj to #aj1jjj ohms4 ,in that case ,c 7amperes7 equals #aaj_/e1jjj1 or #aaj_/aj1jjj--;about #a_/ejth1 or #a_/ajjth of an ampere4 ,this illustrates why an electric current of #aaj volts pressure is not fatal to human beings1 under ordinary circumstances4 ,the body offers too much resistance4 ,but1 if the volts were #a1ajj instead of the usual #aaj used in commercial and private plants for domestic use1 the value of ,c1 by this formula at #e1jjj ohms1 would be nearly #a_/eth ampere4 ,to drive #a_/eth ampere of electricity through the human body would be fatal in many instances4 ,the higher the voltage1 the more dangerous the current4 ,in large water-power installations in the ,far ,west1 where the current must be transmitted over long distances to the spot where it is to be used1 it is occasionally generated at a pressure of #aej1jjj volts4 ,needless to say1 contact with such wires means instant death4 ,before being used for commercial or domestic purposes1 in such cases1 the voltage is stepped down to safe pressures--to #aaj1 or to #bbj1 or to #eej volts--always depending on the use made of it4 ,now1 if instead of interposing four inches of air1 or the human body1 between the mains of our #aaj-volt dynamo1 we connected an incandescent lamp across the mains1 how much electricity would flow from the generator8 ,an incandescent lamp consists of a vacuum bulb of glass1 in which is mounted a slender thread of carbonized fibre1 or fine tungsten wire4 ,to complete a circuit1 the current must flow through this wire or filament4 ,in flowing through it1 the electric current turns the wire or filament white hot--incandescent--and thus turns electricity back into light1 with a small loss in heat4 ,in an ordinary #af candlepower carbon lamp1 the resistance of this filament is #bbj ohms4 ,therefore the amount of current that a #aaj-volt generator can force through that filament is #aaj_/bbj1 or #a_/b ampere4 ,illustration3 ,armature and field coils of a direct current dynamo ,one hundred lamps would provide #ajj paths of #bbj ohms resistance each to carry current1 and the amount required to light #ajj such lamps would be #ajj #a_/b or #ej amperes4 ,every electrical device--a lamp1 a stove1 an iron1 a motor1 etc41--must1 by regulations of the ,fire ,underwriters' ,board be plainly marked with the voltage of the current for which it is designed and the amount of current it will consume4 ,this is usually done by indicating its capacity in watts1 which as we have seen1 means volts times amperes1 and from this one can figure ohms1 by the above formulas4 ,a ,short ,circuit ,we said a few paragraphs back that under no conditions must two bare wires leading from electric mains be permitted to touch each other1 without some form of resistance being interposed in the form of lamps1 or other devices4 ,let us see what would happen if two such bare wires did touch each other4 ,our dynamo as we discover by reading its plate1 is rated to deliver #ej amperes1 let us say1 at #aaj volts pressure4 ,modern dynamos are rated liberally1 and can stand #ajj overload for short periods of time1 without dangerous overheating4 ,let us say that the mains conveying current from the armature to the switchboard are five feet long1 and of ,no4 #b ,b4 ,s4 gauge copper wire1 a size which will carry #ej amperes without heating appreciably4 ,the resistance of this #aj feet of ,no4 #b copper wire1 is1 as we find by consulting a wire table1 4#jjaefj ohms4 ,if we touch the ends of these two five-foot wires together1 we instantly open a clear path for the flow of electric current1 limited only by the carrying capacity of the wire and the back pressure of 4#jjaefj ohms resistance4 ,using ,ohm's ,law1 ,c equals ,e divided by ,r1 we find that ,c 7amperes7 equals #aaj_/4jjaefj or #gj1eae amperes6 ,illustration3 ,a direct current dynamo ,unless this dynamo were properly protected1 the effect of such a catastrophe would be immediate and probably irreparable4 ,in effect1 it would be suddenly exerting a force of nearly #aj1jjj horsepower against the little #aj horsepower water wheel that is driving this dynamo4 ,the mildest thing that could happen would be to melt the feed-wire or to snap the driving belt1 in which latter case the dynamo would come to a stop4 ,if by any chance the little water wheel was given a chance to maintain itself against the blow for an instant1 the dynamo1 rated at #ej amperes1 would do its best to deliver the #gj1eae amperes you called for--and the result would be a puff of smoke1 and a ruined dynamo4 ,this is called a short circuit--one of the first don'ts in handling electricity4 ,as a matter of fact every dynamo is protected against such a calamity by means of safety devices1 which will be described in a later chapter--because no matter how careful a person may be1 a partial short circuit is apt to occur4 ,happily1 guarding against its disastrous effects is one of the simplest problems in connection with the electric plant4 ,direct ,current and ,alternating ,current ,when one has mastered the simple ,ohm's ,law of the electric circuit1 the next step is to determine what type of electrical generator is best suited to the requirements of a farm plant4 ,in the first place1 electric current is divided into two classes of interest here--alternating1 and direct4 ,we have seen that when a wire is moved through the field of a magnet1 there is induced in it two pulsations--first in one direction1 then in another4 ,this is an alternating current1 so called because it changes its direction4 ,if1 with our armature containing hundreds of wires to cut the lines of force of a group of magnets1 we connected the beginning of each wire with one copper ring1 and the end of each wire with another copper ring1 we would have what is called an alternating-current dynamo4 ,simply by pressing a strap of flexible copper against each revolving copper ring1 we would gather the sum of the current of these conductors4 ,its course would be represented by the curved line in the diagram1 one loop on each side of the middle line 7which represents time7 would be a cycle4 ,the number of cycles to the second depends on the speed of the armature2 in ordinary practice it is usually twenty-five or sixty4 ,alternating current has many advantages1 which however1 do not concern us here4 ,except under very rare conditions1 a farmer installing his own plant should not use this type of machine4 ,illustration3 ,diagram of alternating and direct current ,if1 however1 instead of gathering all the current with brushes bearing on two copper rings1 we collected all the current traveling in one direction1 on one set of brushes--and all the current traveling in the other direction on another set of brushes1--we would straighten out this current1 make it all travel in one direction4 ,then we would have a direct current4 ,a direct current dynamo1 the type generally used in private plants1 does this4 ,instead of having two copper rings for collecting the current1 it has a single ring1 made up of segments of copper bound together1 but insulated from each other1 one segment for each set of conductors on the armature4 ,this ring of many segments1 is called a commutator1 because it commutates1 or changes1 the direction of the electric impulses1 and delivers them all in one direction4 ,in effect1 it is like the connecting rod of a steam engine that straightens out the back-and-forth motion of the piston in the steam cylinder and delivers the motion to a wheel running in one direction4 ,such a current1 flowing through a coil of wire would make a magnet1 one end of which would always be the north end1 and the other end the south end4 ,an alternating current1 on the other hand1 flowing through a coil of wire1 would make a magnet that changed its poles with each half-cycle4 ,it would no sooner begin to pull another magnet to it1 than it would change about and push the other magnet away from it1 and so on1 as long as it continued to flow4 ,this is one reason why a direct current dynamo is used for small plants4 ,alternating current will light the same lamps and heat the same irons as a direct current2 but for electric power it requires a different type of motor4 ,types of ,direct ,current ,dynamos ,just as electrical generators are divided into two classes1 alternating and direct1 so direct current machines are divided into three classes1 according to the manner in which their output1 in amperes and volts1 is regulated4 ,they differ as to the manner in which their field magnets 7in whose field of force the armature spins7 are excited1 or made magnetic4 ,they are called series1 shunt1 and compound machines4 ,the ,series ,dynamo ,by referring to the diagram1 it will be seen that the current of a series dynamo issues from the armature mains1 and passes through the coils of the field magnets before passing into the external circuit to do its work4 ,the residual magnetism1 or the magnetism left in the iron cores of the field magnets from its last charge1 provides the initial excitation1 when the machine is started4 ,as the resistance of the external circuit is lowered1 by turning on more and more lights1 more and more current flows from the armature1 through the field magnets4 ,each time the resistance is lowered1 therefore1 the current passing through the field magnets becomes more dense in amperes1 and makes the field magnets correspondingly stronger4 ,we have seen that the voltage depends on the number of lines of magnetic force cut by the armature conductors in a given time4 ,if the speed remains constant then1 and the magnets grow stronger and stronger1 the voltage will rise in a straight line4 ,when no current is drawn1 it is #j2 at full load1 it may be #ajj volts1 or #ejj1 or #a1jjj according to the machine4 ,this type of machine is used only in street lighting1 in cities1 with the lights connected in series1 or one after another on the same wire1 the last lamp finally returning the wire to the machine to complete the circuit4 ,this type of dynamo has gained the name for itself of mankiller1 as its voltage becomes enormous at full load4 ,it is unsuitable1 in every respect1 for the farm plant4 ,its field coils consist of a few turns of very heavy wire1 enough to carry all the current of the external circuit1 without heating4 ,illustration3 ,connections of a series dynamo ,the ,shunt ,dynamo ,the shunt dynamo1 on the other hand1 has field coils connected directly across the circuit1 from one wire to another1 instead of in series4 ,these coils consist of a great many turns of very fine wire1 thus introducing resistance into the circuit1 which limits the amount of current 7amperes7 that can be forced through them at any given voltage4 ,as a shunt dynamo is brought up to its rated speed1 its voltage gradually rises until a condition of balance occurs between the field coils and the armature4 ,there it remains constant4 ,when resistance on the external circuit is lowered1 by means of turning on lamps or other devices1 the current from the armature increases in working power1 by increasing its amperes4 ,its voltage remains stationary2 and1 since the resistance of its field coils never changes1 the magnets do not vary in strength4 ,illustration3 ,connections of a shunt dynamo ,the objection to this type of machine for a farm plant is that1 in practice1 the armature begins to exercise a de-magnetizing effect on the field magnets after a certain point is reached--weakens them2 consequently the voltage begins to fall4 ,the voltage of a shunt dynamo begins to fall after half-load is reached2 and at full load1 it has fallen possibly #bj per cent4 ,a rheostat1 or resistance box on the switchboard1 makes it possible to cut out or switch in additional resistance in the field coils1 thus varying the strength of the field coils1 within a limit of say #ae per cent1 to keep the voltage constant4 ,this1 however1 requires a constant attendance on the machine4 ,if the voltage were set right for #aj lights1 the lights would grow dim when #ej lights were turned on2 and if it were adjusted for #ej lights1 the voltage would be too high for only ten lights--would cause them to burn out4 ,shunt dynamos are used for charging storage batteries1 and are satisfactory for direct service only when an attendant is constantly at hand to regulate them4 ,the ,compound ,dynamo ,the ideal between these two conditions would be a compromise1 which included the characteristics of both series and shunt effects4 ,that is exactly what the compound dynamo effects4 ,a compound dynamo is a shunt dynamo with just enough series turns on its field coils1 to counteract the de-magnetizing effect of the armature at full load4 ,a machine can be designed to make the voltage rise gradually1 or swiftly1 by combining the two systems4 ,for country homes1 the best combination is a machine that will keep the voltage constant from no load to full load4 ,a so-called flat-compounded machine does this4 ,in actual practice1 this voltage rises slightly at the half-load line--only two or three volts1 which will not damage the lamps in a #aaj-volt circuit4 ,the compound dynamo is therefore self-regulating1 and requires no attention1 except as to lubrication1 and the incidental care given to any piece of machinery4 ,any shunt dynamo can be made into a compound dynamo1 by winding a few turns of heavy insulated wire around the shunt coils1 and connecting them in series with the external circuit4 ,how many turns are necessary depends on conditions4 ,three or four turns to each coil usually are sufficient for flat compounding4 ,if the generating plant is a long distance from the farm house where the light1 heat1 and power are to be used1 the voltage drops at full load1 due to resistance of the transmission wires4 ,to overcome this1 enough turns can be wound on top of the shunt coils to cause the voltage to rise at the switchboard1 but remain stationary at the spot where the current is used4 ,the usual so-called flat-compounded dynamo1 turned out by manufacturers1 provides for constant voltage at the switchboard4 ,such a dynamo is eminently fitted for the farm electric plant4 ,any other type of machine is bound to cause constant trouble and annoyance4 ,illustration3 ,connections of a compound dynamo ,,chapter ,,vi ,,what ,,size ,,plant ,,to ,,install ,the farmer's wife his partner--,little and big plants--,limiting factors--,fluctuations in water supply--,the average plant--,the actual plant--,amount of current required for various operations--,standard voltage--,a specimen allowance for electric light--,heating and cooking by electricity--,electric power3 the electric motor4 ,the farmer's wife becomes his partner when he has concluded the preliminary measurements and surveys for building his water-power electric plant4 ,now the question is1 how big a plant is necessary1 or how small a plant can he get along with4 ,electricity may be used for a multitude of purposes on the farm1 in its sphere of furnishing portable light1 heat and power2 but when this multitude of uses has been enumerated1 it will be found that the wife shares in the benefits no less than the farmer himself4 ,the greatest dividend of all1 whether dividends are counted in dollars or happiness1 is that electricity takes the drudgery out of housework4 ,here1 the work of the farmer himself ends when he has brought electricity to the house1 just as his share in housework ends when he has brought in the kerosene1 and filled the woodbox4 ,of the light and heat1 she will use the lion's share2 and for the power1 she will discover heretofore undreamed-of uses4 ,so she must be a full partner when it comes to deciding how much electricity they need4 ,how much electricity1 in terms of light1 heat1 and power1 will the farmer and his wife have use for8 ,how big a plant should be installed to meet the needs of keeping house and running the farm8 ,the answer hangs mainly on how much water-power there is available1 through all the seasons of the year1 with which to generate electricity4 ,beyond that1 it is merely a question of the farmer's pocketbook4 ,how much money does he care to spend8 ,electricity is a cumulative poison4 ,the more one uses it1 the more he wants to use it4 ,after a plant has been in operation a year1 the family have discovered uses for electricity which they did not think of in the beginning4 ,for this reason1 it is well to put in a plant larger than the needs of the moment seem to require4 ,an electrical horsepower or two one way or another will not greatly change the first cost1 and you will always find use for any excess4 ,once for all1 to settle the question of water-power1 the water wheel should be twice the normal capacity of the dynamo it drives1 in terms of power4 ,this allows for overload1 which is bound to occur occasionally2 and it also insures smooth running1 easy governing1 and the highest efficiency4 ,since the electric current1 once the plant is installed1 will cost practically nothing1 the farmer can afford to ignore the power going to waste1 and consider only how to get the best service4 ,the ,two ,extremes ,the amount of water to be had to be turned into electricity1 will vary with location1 and with the season4 ,it may be only enough1 the greater part of the year1 for a toy plant--a very practical toy1 by the way--one that will keep half a dozen lights burning in the house and barn at one time2 under some conditions water may be so scarce that it must be stored for three or four days to get enough power to charge a storage battery for these six or eight lights4 ,a one-quarter1 or a one-half kilowatt electrical generator1 with a one horsepower 7or smaller7 wheel1 will light a farmstead very satisfactorily--much better than kerosene lamps4 ,on the other hand1 the driving power of your wheel may be sufficient to furnish #ej or #ajj lights for the house1 barn1 and out-buildings1 and barn-yard and drives2 to provide ample current for irons1 toasters1 vacuum cleaners1 electric fans1 etc42 to do all the cooking and baking and keep the kitchen boiler hot2 and to heat the house in the coldest weather with a dry clean heat that does not vitiate the air1 with no ashes1 smoke or dust or woodchopping--nothing but an electric switch to turn on and off2 and to provide power for motors ranging from tiny ones to run the sewing machine1 to one of #ae horsepower to do the threshing4 ,a plant capable of developing from #cj to #ej kilowatts of electricity1 and requiring from #ej to #ajj horsepower at the water wheel1 would do all this1 depending on the size of the farmstead4 ,one hundred horsepower is a very small water project1 in a commercial way2 and there are thousands of farms possessing streams of this capacity4 ,fluctuations in ,water ,supply ,it would be only during the winter months that such a plant would be driven to its full capacity2 and since water is normally plentiful during these months1 the problem of power would be greatly simplified4 ,the heaviest draft on such a plant in summer would be during harvesting2 otherwise it would be confined to light1 small power for routine work1 and cooking4 ,thus1 a plant capable of meeting all the ordinary requirements of the four dry months of summer1 when water is apt to be scarce1 doubles or quadruples its capacity during the winter months1 to meet the necessities of heat for the house4 ,a dynamo requires only as much power to drive it1 at any given time1 as is being used in terms of electricity4 ,there is some small loss through friction1 of course1 but aside from this the power required of the prime mover 7the water wheel7 is always in proportion to the amount of current flowing4 ,when water is scarce1 and the demands for current for heating are low1 it is good practice to close a portion of the buckets of the turbine wheel with wooden blocks provided for this purpose4 ,it is necessary to keep the speed of the dynamo uniform under all water conditions2 and where there is a great fluctuation between high and low water periods1 it is frequently necessary to have a separate set of pulleys for full gate and for half-gate4 ,the head must remain the same1 under all conditions4 ,changing the gate is in effect choking or opening the nozzle supplying the wheel1 to cut down or increase its consumption of water4 ,the ,average ,plant ,it will be the exceptional plant1 however1 among the hundreds of thousands to be had on our farms1 which will banish not only the oil lamp and kitchen stove1 but all coal or wood burning stoves as well--which will heat the house in below-zero weather1 and provide power for the heavier operations of the farm4 ,also1 on the other hand1 it will be the exceptional plant whose capacity is limited to furnishing a half-dozen lights and no more4 ,a happy medium between these two conditions is the plant large enough to supply between five and ten electrical horsepower1 in all seasons4 ,such a plant will meet the needs of the average farm1 outside of winter heating and large power operations1 and will provide an excess on which to draw in emergencies1 or to pass round to one's neighbors4 ,it is such a plant that we refer to when we say that 7not counting labor7 its cost1 under ordinary conditions should not greatly exceed the price of one sound young horse for farm work4 ,since the plant we described briefly in the first chapter1 meets the requirements of this average plant let us inquire a little more fully into its installation1 maintenance1 and cost4 ,an ,actual ,plant ,in this instance1 the water-power was already installed1 running to waste1 in fact4 ,the wheel consists of the so-called thirty-six inch vertical turbine1 using #ahe square inches of water1 under a #ad-;foot head4 ,water is supplied to this wheel by a wooden penstock #cc inches square1 inside measurements1 and sloping at an angle of #cj from the flume to the wheel4 ,illustration3 ,details of voltmeter or ammeter ,this wheel1 under a #ad-;foot head1 takes #b1cab cubic feet of water a minute2 and it develops #df4ih actual horsepower 7as may be figured by using the formulas of ,chapter ,,iii74 ,the water supply is provided by a small mountain river4 ,the dam is #aj feet high1 and the race1 which feeds the flume from the mill pond is #ge yards long4 ,the race has two spillways1 one near the dam1 and the second at the flume itself1 to maintain an even head of water at all times4 ,half-,gate ,since the water supply varies with the seasons1 it has been found practical to run the wheel at half-gate--that is1 with the gate only half-open4 ,a set of bevel gears work the main shaft1 which runs at approximately #bjj revolutions per minute2 and the dynamo is worked up to its required speed of #a1ejj revolutions per minute through a countershaft4 ,the dynamo is a modern four-pole machine1 compound-wound1 with a rated output of #df amperes1 at #abe volts--in other words a dynamo of #e4ge kilowatts capacity1 or #g4g electrical horsepower4 ,at full load this dynamo would require a driving power of #aj horsepower1 counting it as #ge per cent efficient2 and1 to conform to our rule of two water horsepower to one electrical horsepower1 the wheel should be capable of developing #bj horsepower4 ,as a matter of fact1 in this particular instance1 shutting down the wheel to half-gate more than halves the rated power of the wheel1 and little more than #ae horsepower is available4 ,this allowance has proved ample1 under all conditions met with1 in this plant4 ,the dynamo is mounted on a firm floor foundation2 and it is belted from the countershaft by an endless belt running diagonally4 ,a horizontal belt drive is the best4 ,vertical drive should be avoided wherever possible4 ,the ,switchboard ,the switchboard originally consisted of a wooden frame on which were screwed ordinary asbestos shingles1 and the instruments were mounted on these4 ,later1 a sheet of electric insulating fibre was substituted1 for look's sake4 ,the main requisite is something substantial--and fireproof4 ,the switchboard instruments consist of a voltmeter1 with a range of from #j to #aej volts2 an ammeter1 with a range1 #j to #ge amperes2 a field regulating rheostat 7which came with the dynamo72 a main switch1 with cartridge fuses protecting the machine against a draft of current over #fj amperes2 and two line switches for the two owners1 one fuse at #bj amperes1 and the other at #dj amperes4 ,electric fuses are either cartridges or plugs1 enclosing lead wire of a size corresponding to their rating4 ,all the current of the line they protect passes through this lead wire4 ,if the current drawn exceeds the capacity of the lead wire1 it melts from the heat1 and thus opens the circuit1 and cuts off the current4 ,illustration3 ,a switchboard and its connections3 ,g4 ,dynamo2 ,a4 ,shunt field coils2 ,b4 ,series coils2 ,,dd4 ,fuses2 ,,ff4 ,main switch2 ,f4 ,field switch2 ,c4 ,ammeter2 ,v4 ,voltmeter2 ,e4 ,lamp2 ,r4 ,rheostat4 ,dotted lines show connections on back of board ,items of ,cost ,this water wheel would cost #bej new4 ,there is a duplicate in the neighborhood bought at second-hand1 for #abe4 ,the dynamo cost #ij1 and was picked up second-hand in ,new ,york ,city4 ,new it would cost #aej4 ,the voltmeter cost #g1 and the ammeter #aj2 and the switches and fuses could be had for #e4 ,a wheel one-half the size1 using one-half the amount of water at full gate1 would do the work required1 and the cost would be correspondingly less4 ,capacity ,this plant supplies two farms with electric light4 ,one farm 7that of the owner of the wheel7 has #cj lamps1 of #af candlepower each1 and two barn-yard lamps of #ib candlepower each4 ,his wife has an electric iron and an electric water heater4 ,needless to say1 all these lamps1 and the iron and water heater are not in use at one time4 ,illustration3 ,carbon ,lamps ,gem ,type 7#a_/d scale7 ,the partner who owns the electric part of the plant has #cj lamps in his house and barn1 many of them being #be watt tungsten1 which give more light for less power1 but cost more to buy4 ,they are not all in use at one time1 though 7since the current costs nothing7 the inclination is to turn them on at night and let them burn4 ,in his kitchen he has an electric range1 and a water heater for the #dj gallon boiler4 ,in addition to this he has all sorts of appliances1--irons1 toasters1 grills1 a vacuum cleaner1 a vibrator1 etc4 ,naturally all these appliances are not in use at one time1 else the draft on the plant would be such as to blow the fuses4 ,for instance1 all the baking is done in daylight2 and when the oven is used after dark1 they are careful to turn off all lights not needed4 ,an ideal plant1 of course1 would be a plant big enough to take care of the sum of lamps and handy devices used at one time4 ,to make this plant ideal1 7for1 being an actual affair1 it has developed some short-comings1 with the extension of the use of electricity7 it would require a dynamo whose capacity can be figured1 from the following3 ,watts #ae carbon lamps1 #af candlepower1 #fj watts each #ijj #aj tungsten lamps1 #bj candlepower1 #be watts each #bej #b tungsten lamps1 #ib candlepower1 #ajj watts each #bjj ,water heater1 continuous service #hjj ,toaster1 occasional service #fjj ,iron1 occasional service #djj ,oven-baking1 roasting1 etc #b1jjj #b stove plates #a1jjj watts each #b1jjj #a stove plate #djj ,vacuum cleaner1 occasional service #bjj ,vibrator1 occasional service #ajj ,small water heater1 quart capacity #djj ,small motor1 #a_/d horsepower1 occasional #bej ,motor1 #a_/b hp1 pumping water1 etc #ejj ,electric fan1 occasional service #ajj ------- ,total current1 one house #i1ajj #cj carbon lamps1 #af candlepower1 #fj #a1hjj #b lamps1 #ajj watt tungsten #bjj ,electric iron #djj ,small water or milk heater #fjj ------- ,total current1 #bnd house #c1jjj #ast house #i1ajj ------- #ab1ajj ,thus1 in this plant1 if every electrical device were turned on at once1 the demand on the dynamo would be for #ab4a kilowatts1 or an overload of over #ajj per cent4 ,the main-switch fuse1 being for #fj amperes1 would blow or melt1 and cut off all current for the moment4 ,to repair the damage would be merely the work of a second--and at a cost of a few cents--simply insert a new fuse1 of which there must be a supply on hand at all times4 ,or1 if either owner exceeded his capacity1 the line fuses 7one for #bj amperes1 and the other for #dj amperes7 would instantly cut off all current from the greedy one4 ,illustration3 #be and #dj watt ,mazda tungsten lamps 7#a_/d scale7 ,lessons ,from ,this ,plant ,the story of this plant illustrates two things which the farmer and his wife must take into account when they are figuring how much electricity they require4 ,first1 it illustrates how one uses more and more current1 as he finds it so serviceable and labor-saving1 and at the same time free4 ,the electric range and the water boiler1 in the above instance1 were later acquisitions not counted on in figuring the original installation4 ,second1 it illustrates1 that while the normal load of this generator is #e4ge kilowatts1 one does not have to limit the electrical conveniences in the home to this amount4 ,true1 he cannot use more electricity than his plant will produce at any one time1--but it is only by a stretch of the imagination that one may conceive the necessity of using them all at once4 ,ironing1 baking1 and the use of small power are usually limited to daylight hours when no lights are burning4 ,as a matter of fact1 this plant has proved satisfactory in every way2 and only on one or two occasions have fuses been blown1 and then it was due to carelessness4 ,a modern dynamo is rated liberally4 ,it will stand an overload of as much as #ajj per cent for a short time--half an hour or so4 ,the danger from overloading is from heating4 ,when the machine grows too hot for the hand1 it is beginning to char its insulation1 to continue which1 of course would ruin it4 ,the best plant is that which works under one-half or three-quarters load1 under normal demands4 ,standard ,voltage ,we are assuming the farmer's plant to be1 in #ii cases out of #ajj1 the standard #aaj-volt1 direct current type4 ,such a plant allows for at least a #aj per cent regulation1 in voltage1 up or down the scale2 supplies for this voltage are to be had without delay in even the more remote parts of the country1 and 7being sold in greater volume7 they are cheaper than those for other voltages4 ,there are two general exceptions to this rule as to #aaj-volt plants3 7#a7 ,if the plant is located at a distance greater than a quarter of a mile from the house1 it will be found cheaper 7in cost of transmission line1 as will be shown later7 to adopt the #bbj-volt plant2 7#b71 ,if the water supply is so meagre that it must be stored for many hours at a time1 and then used for charging storage batteries1 it will be found most economical to use a #cj-volt plant4 ,a storage battery is made up of cells of approximately #b volts each2 and1 since more than #ee such cells would be required for a #aaj-volt installation1 its cost would be prohibitive1 with many farmers4 ,so we will assume that this plant is a #aaj-volt plant1 to be run without storage battery4 ,it will be well to make a chart1 dividing the farm requirements into three heads--light1 heat1 and power4 ,light ,illustration3 #fj and #ajj watt ,mazda tungsten lamp4 ,these lamps may be had in sizes from #aj to #ejj watts 7#a_/d scale7 ,illustration3 ,the lamp of the future4 ,a #ajjj watt ,mazda nitrogen lamp1 giving #bjjj candlepower 7#a_/d scale7 ,light is obtained by means of incandescent lamps4 ,there are two styles in common use1 the carbon and the tungsten lamp4 ,it requires #c4e to #d watts of electricity to produce one candlepower in a carbon lamp4 ,it requires from #a to #a4be watt to produce one candlepower in the tungsten lamp4 ,the new nitrogen lamp1 not yet in general use1 requires only #a_/b watt to the candlepower4 ,since tungsten lamps give three times the light of the carbon lamp1 they are the most economical to use in the city or town where one is paying for commercial current4 ,but1 in the country where water-power furnishes current for nothing1 it will be found most economical to use the carbon lamp1 since its cost at retail is #af cents1 as compared with #cj cents for a corresponding size in tungsten4 ,a #fj watt carbon lamp1 of #af candlepower2 or a #be watt tungsten lamp1 of #bj candlepower1 are the sizes to use4 ,in hanging lamps1 as over the dining room table1 a #ajj watt tungsten lamp1 costing #gj cents1 and giving #ib candlepower light is very desirable2 and for lighting the barn-yard1 these #ajj watt tungsten lamps should be used4 ,for reading lamps1 the tungsten style1 of #dj or #fj watt capacity1 will be found best4 ,otherwise1 in all locations use the cheaper carbon lamp4 ,both styles have a rated life of #a1jjj hours1 after which they begin to fall off in efficiency4 ,here again1 the farmer need not worry over lack of highest efficiency1 as a lamp giving only #hj per cent of its rated candlepower is still serviceable when he is not paying for the current4 ,with care not to use them at voltages beyond their ratings1 lamps will last for years4 ,a ,specimen ,light ,allowance ,below is a typical table of lights for a large farm house1 the barns and barn-yard4 ,it is given merely as a guide1 to be varied for each individual case3 ,watts ,kitchen1 #b lights #fj watts #abj ,dining room1 #a light1 tungsten #ajj ,living room1 table lamp with #c tungstens #dj #abj ,living room1 #b wall fixtures1 #d lamps #fj watts #bdj ,parlor1 same as living room #cfj ,pantry1 #a hanging lamp #fj ,cellar1 one portable lamp #fj ,woodshed1 #a hanging lamp #fj #b bedrooms1 #b lights each #fj #bdj #b bed rooms1 #a light each #fj #abj ,bathroom1 #a turn-down light1 #fj #fj ,hall1 downstairs1 #b lights #fj #abj ,hall1 upstairs1 #a light #fj ,attic1 #a light #fj ,porch1 #a light #fj ,barn and barn-yard3 ,barn-yard entrance1 #a tungsten #ajj ,watering trough1 #a #ajj ,front gate1 #a #ajj ,horse barn1 #d lights #fj #bdj ,cow barn1 #d lights #fj #bdj ,pig house1 #a light #fj ,hay barn1 #b lights1 #fj #abj ------- ,total for farmstead #b1hjj ,this provides for #dd lights1 an extremely liberal allowance4 ,how many of these lights will be burning at any one time8 ,probably not one-half of them2 yet the ideal plant is that which permits all fixtures to be in service at one time on the rare occasions when necessary4 ,thus1 for lighting only1 #b1hjj watts maximum service would require a #d kilowatt generator1 and #aj water horsepower1 on the liberal rating of two to one4 ,a #c kilowatt generator would take care of these lights1 with a #cj per cent overload 7which is not excessive7 for maximum service4 ,the above liberal allowance of lights may be cut in two1 or four--or even eight--and still throw a kerosene lamp in shadow4 ,it all depends on the number of lights one wants burning at one time2 and the power of the water wheel4 ,if the #cf carbon lights in the above table were replaced by #be watt tungsten lights1 the saving in power would be #ce watts each1 or #a1bfj watts1 nearly two electrical horsepower2 while the added first cost would be #ad cents a light1 or #e4jd4 ,a generator of #b kilowatt capacity would take care of all these lights then1 with #dfj watts to spare4 ,heating ,electric heating and cooking is in its infancy1 due to the prohibitive cost of commercial current in our cities4 ,here the farmer has the advantage again1 with his cheap current4 ,for heating the house1 it is calculated that #b watts is required for each cubic foot of air space in a room1 during ordinary winter weather4 ,thus1 a room #aj #ab1 and #h feet high1 would contain #ifj cubic feet1 and would require #a1hbj watts energy to heat it in cold weather4 ,five such rooms would require #i4a kilowatts2 and #aj such rooms1 or their equivalent1 would require #ah4b kilowatts4 ,electric heating devices are divided into two classes3 7#a7 those which can be used on lamp circuits1 and do not draw more than #ffj watts each2 and 7#b7 those which draw more than #ffj1 therefore require special wiring4 ,the capacity of these devices is approximately as follows3 ,lamp circuit devices3 ,watts ,electric iron #djj to #ffj ,toaster #cej to #ffj ,vacuum cleaner #bjj to #djj ,grill #djj to #ffj ,small water heater #djj to #ffj ,hot plates #djj to #ffj ,lamp circuit devices3 ,coffee percolator #djj to #ffj ,chafing dish #djj to #ffj ,electric fan #ajj to #bej ,special circuit devices3 ,hot water boiler heater #hjj to #a1bjj ,small ovens #ffj to #a1bjj ,range ovens #a1bjj to #c1jjj ,range1 hot plates #djj to #a1cjj ,radiators 7small7 #gej to #a1ejj ,radiators 7large7 #a1ejj to #f1jjj ,the only device in the above list which is connected continuously1 is the hot water boiler1 and this can be credited with at least one electrical horsepower #bd hours a day4 ,it is a small contrivance1 not much bigger than a quart can1 attached to the back of the kitchen boiler1 and it keeps the water hot throughout the house at all hours4 ,its cost will vary with the make1 ranging from #h to #ae2 and since it is one of the real blessings of the farm kitchen and bathroom1 it should be included in all installations where power permits4 ,electric radiators will be used #bd hours a day in winter1 and not at all in summer4 ,they are portable1 and can be moved from room to room1 and only such rooms as are in actual use need be heated4 ,the other devices are for intermittent service1 many of them 7like the iron7 for only a few hours each week4 ,the grill1 chafing dish1 coffee percolator1 etc41 which are used on the dining room table while the family is at meals1 each draw an equivalent of from #f to #aj carbon lights4 ,by keeping this in view and turning off spare lights1 one can have the use of them1 with even a small plant4 ,thus1 a one kilowatt plant permits the use of any one of these lamp circuit devices at a time1 with a few lights in addition4 ,power ,electric power is to be had through motors4 ,a direct current dynamo and a direct current motor are identical in construction4 ,that is1 a motor becomes a generator if belted to power2 and a generator becomes a motor1 if connected to electric mains4 ,this is best illustrated by citing the instance of a trans-continental railroad which crosses the ,bitter ,root ,mountains by means of electric power4 ,running #bjj miles up a #b per cent grade1 it is drawn by its motors4 ,coasting #bjj miles down the #b per cent grade on the other side of the mountains1 its motors become generators4 ,they act as brakes1 and at the same time they pump the power of the coasting weight of this train back into the wires to help a train coming up the other side of the mountains4 ,illustration3 ,connections of shunt motor and starting rheostat ,just as there are three types of direct current generators1 so there are three types of direct current motors3 series1 shunt1 and compound1 with features already explained in the case of generators4 ,motors are rated by horsepower1 and generators are rated by kilowatts4 ,thus a one kilowatt generator has a capacity of #a1jjj watts2 as a motor1 it would be rated as #ajjj_/gdf horsepower1 or #a4cd horsepower4 ,their efficiency varies with their size1 ranging from #dj to #fj per cent in very small motors1 and up to #ie per cent in very large ones4 ,the following table may be taken as a guide in calculating the power required by motors1 on #aaj-volt circuits3 #a_/d ,horsepower #b-a_/b amperes1 or #bge watts #a_/b hp #d-a_/b amperes1 or #ejj watts #a hp #i amperes1 or #iij watts #b hp #ag amperes1 or #a4ig kilowatts #c hp #bf amperes1 or #b4hf kilowatts #e hp #dj amperes1 or #d4dj kilowatts #g-a_/b hp #fj amperes1 or #f4fj kilowatts #aj hp #gf amperes1 or #h4cf kilowatts #ae hp #aab amperes1 or #ab4cb kilowatts ,an electric motor1 in operation1 actually generates electricity1 which it pushes back into the line as a counter-electromotive-force4 ,the strength of this counter force1 in volts1 depends on the motor's speed1 the same as if it were running as a dynamo4 ,for this reason1 when a motor is started1 and before it comes up to speed1 there would be a rush of current from the line1 with nothing to hold it back1 and the motor would be burned out unless some means were provided to protect it for the moment4 ,this is done by means of a starting rheostat1 similar to the regulating rheostat on the dynamo switchboard4 ,this resistance box is connected in series with the armature1 in the case of shunt and compound motors2 and with the entire motor circuit in the case of a series machine4 ,a series motor has a powerful starting torque1 and adjusts its speed to the load4 ,it is used almost altogether in street cars4 ,it can be used in stump pulling1 or derrick work1 such as using a hay fork4 ,it must always be operated under load1 otherwise1 it would increase in speed until it tore itself to pieces through mechanical strain4 ,the ingenious farmer who puts together an electric plow1 with the mains following behind on a reel1 will use a series motor4 ,a shunt motor should be used in all situations where a fairly uniform speed under load is required1 such as separating1 in milking machines1 running a lathe1 an ensilage cutter1 vacuum cleaners1 grinders1 etc4 ,the compound motor has the characteristics of the series and shunt motors1 giving an increased starting torque1 and a more nearly constant speed under varying loads than the shunt motor1 since the latter drops off slightly in speed with increasing load4 ,flexible ,power ,an electric motor is an extremely satisfactory form of power because it is so flexible4 ,thus1 one may use a five horsepower motor for a one horsepower task1 and the motor will use only one electrical horsepower in current--just enough to overcome the task imposed on it4 ,for this reason1 a large-sized motor may be used for any operation1 from one requiring small power1 up to its full capacity4 ,it will take an overload1 the same as a dynamo4 ,in other words it is eager for any task imposed on it2 therefore it must be protected by fuses1 or it will consume itself1 if too big an overload is imposed on it4 ,a one horsepower shunt or compound motor is very serviceable for routine farm operations1 such as operating the separator1 the churn1 the milking machine1 grinder1 pump1 and other small power jobs4 ,motors of #a_/d horsepower are handy in the kitchen1 for grinding knives1 polishing silver1 etc41 and can be used also for vacuum cleaners1 and running the sewing machine4 ,for the larger operations1 motors will vary from three horsepower for cutting ensilage1 to fifteen horsepower for threshing4 ,they can be mounted on trucks and conveyed from one point to another1 being fed current from the mains by means of suitable wires wound on reels4 ,remember1 in estimating the size of your plant for light1 heat1 and power1 that it does not have to be big enough to use all the devices at one time4 ,also remember1 that two water horsepower to one electrical horsepower is a very liberal allowance2 and that a generator working under one-half or two-thirds capacity at normal loads will require less attention than a machine constantly being worked above its capacity4 ,therefore1 let your generator be of liberal size1 because the difference in cost between a #e and #aj kilowatt machine is not in proportion to their capacity4 ,in fact 7especially among second-hand machines71 the difference in cost is very small4 ,the mere fact that the generator is of #aaj electrical horsepower capacity does not require a turbine of #bj horsepower4 ,the chances are that 7unless you wish to heat your house and do large power jobs7 you will not use more than #c to #e electrical horsepower normally2 therefore an allowance of #aj water horsepower1 in this case1 would be ample4 ,a plant used simply for lighting the house and barn1 for irons1 and toasters1 and one horsepower motors1 need not exceed #b or #b-a_/b kilowatts for the generator1 and #e or #f horsepower for the turbine wheel4 ,normally it would not use one-half this capacity4 ,,chapter ,,vii ,,transmission ,,lines ,copper wire--,setting of poles--,loss of power in transmission--,ohm's ,law and examples of how it is used in figuring size of wire--,copper-wire tables--,examples of transmission lines--,when to use high voltages--,over-compounding a dynamo to overcome transmission loss4 ,having determined on the location of the farm water-power electric plant1 and its capacity1 in terms of electricity1 there remains the wiring1 for the transmission line1 and the house and barn4 ,for transmission lines1 copper wire covered with waterproof braid--the so-called weatherproof wire of the trade--is used4 ,under no circumstances should a wire smaller than ,no4 #h1 ,b4 ,s4 gauge be used for this purpose1 as it would not be strong enough mechanically4 ,the poles should be of chestnut or cedar1 #be feet long1 and set four feet in the ground4 ,where it is necessary to follow highways1 they should be set on the fence line2 and in crossing public highways1 the ordinance of your own town must guide you4 ,some towns prescribe a height of #ai feet above the road1 others #bg feet1 some #cj4 ,direct current1 such as is advised for farm installations1 under ordinary circumstances1 does not affect telephone wires1 and therefore transmission lines may be strung on telephone poles4 ,poles are set at an average distance of #h rods2 they are set inclined outward on corners4 ,sometimes it is necessary to brace them with guy wires or wooden braces4 ,glass insulators are used to fasten the wires to the cross-arms of the poles1 and the tie-wires used for this purpose must be the same size as the main wire and carry the same insulation4 ,size of ,wire for ,transmission ,to determine the size of the transmission wires will require knowledge of the strength of current 7in amperes7 to be carried1 and the distance in feet4 ,in transmission1 the electric current is again analogous to water flowing in pipes4 ,it is subject to resistance1 which cuts down the amount of current 7in watts7 delivered4 ,illustration3 ,bringing wires into the house or barn ,the loss in transmission is primarily measured in volts2 and since the capacity of an electric current for work equals the volts multiplied by amperes1 which gives watts1 every volt lost reduces the working capacity of the current by so much4 ,this loss is referred to by electrical engineers as the ,c#b,r loss1 which is another way of saying that the loss is equal to the square of the current in amperes1 multiplied by ohms resistance4 ,thus1 if the amperes carried is #aj1 and the ohms resistance of the line is #e1 then the loss in watts to convey that current would be 7#aj #aj7 #e1 or #ejj watts1 nearly a horsepower4 ,the pressure of one volt 7as we have seen in another chapter7 is sufficient to force one ampere1 through a resistance of one ohm4 ,such a current would have no capacity for work1 since its pressure would be consumed in the mere act of transmission4 ,if1 however1 the pressure were #aaj volts1 and the current one ampere1 and the resistance one ohm1 the effective pressure after transmission would be #aaj-a1 or #aji volts4 ,to force a #aaj-volt current of #ej amperes through the resistance of one ohm1 would require the expenditure of #ej volts pressure4 ,its capacity for work1 after transmission1 would be #aaj-ej1 or #fj volts1 #ej amperes1 or #c1jjj watts4 ,as this current consisted of #aaj #ej1 or #e1ejj watts at the point of starting1 the loss would be #b1ejj watts1 or about #de per cent4 ,it is bad engineering to allow more than #aj per cent loss in transmission4 ,there are two ways of keeping this loss down4 ,one is by increasing the size of the transmission wires1 thus cutting down the resistance in ohms2 the other way is by raising the voltage1 thus cutting down the per cent loss4 ,for instance1 suppose the pressure was #a1ajj volts1 instead of #aaj volts4 ,five amperes at #a1ajj volts pressure1 gives the same number of watts1 power1 as #ej amperes1 at #aaj volts pressure4 ,therefore it would be necessary to carry only #e amperes1 at this rate4 ,the loss would be #e volts1 or less than #a_/b of #a per cent1 as compared with #de per cent with #aaj volts4 ,illustration3 ,splicing transmission wire ,in large generating stations1 where individual dynamos frequently generate as much as #bj1jjj horsepower1 and the current must be transmitted over several hundred miles of territory1 the voltage is frequently as high as #aej1jjj1 with the amperes reduced in proportion4 ,then the voltage is lowered to a suitable rate1 and the amperage raised in proportion1 by special machinery1 at the point of use4 ,it is the principle of the ,c#b,r loss1 which the farmer must apply in determining the size of wire he is to use in transmitting his current from the generator switchboard to his house or barn4 ,the wire table on page #aei1 together with the formula to be used in connection with it1 reduce the calculations necessary to simple arithmetic4 ,in this table the resistance of the various sizes of wire is computed from the fact that a wire of pure copper #a foot long1 and #a_/ajjj inch in diameter 7equal to one circular mill7 offers a resistance of #aj4f ohms to the foot4 ,the principle of the ,c#b,r loss is founded on ,ohm's ,law1 which is explained in ,chapter ,v4 ,the formula by which the size of transmission wire is determined1 for any given distance1 and a given number of amperes1 is as follows3 ,distance ft4 one way #bb ,no4 of amperes circular ---------------------------------------- -- mills4 ,number of volts lost ,in other words1 multiply the distance in feet from mill to house by #bb1 and multiply this product by the number of amperes to be carried4 ,then divide the product by the number of volts to be lost2 and the result will be the diameter of the wire required in circular mills4 ,by referring to the table above1 the ,b4 ,s4 gauge of the wire necessary for transmission1 can be found from the nearest corresponding number under the second column1 entitled circular mills area4 ,,copper ,,wire ,,table ---------------------------------------- ----------------------- ,area in 7,r7 ,ohms ,b4 ,s4 ,feet circular per #a1jjj ,feet 7,r7 ,ohms ,gauge per ,lb4 mills feet per ,ohm per pound ---------------------------------------- ----------------------- #jjjj #a4efa #baa1fjj 4#jdijd #bj1cib4ij 4#jjjjgfec #jjj #a4ifi #afg1hje 4#jfahd #af1agb4aj 4#jjjabafi #jj #b4dhb #acc1jgi 4#jggig #ab1hbe4dj 4#jjjaidch #j #c4acj #aje1ecd 4#jihbi #aj1agf4dj 4#jjjcjgcd #a #c4idg #hc1fid 4#abcih #h1jff4jj 4#jjjdhibj #b #d4igg #ff1cgc 4#aefcc #f1cif4gj 4#jjjggghd #c #f4bgf #eb1fcd 4#aigad #e1jgb4ej 4#jjabcgjj #d #g4iad #da1gdb 4#bdheh #d1jbb4ij 4#jjaifffj #e #i4ihj #cc1ajb 4#cacdf #c1aij4bj 4#jjcabgcj #f #ab4eh #bf1bej 4#ciebh #b1ebi4ij 4#jjdigbhj #g #ae4hg #bj1haf 4#dihde #b1jjf4bj 4#jjgijghj #h #bj4ja #af1eji 4#fbhdj #a1eia4aj 4#jabegaij #i #be4bc #ac1jid 4#gibdb #a1bfb4jj 4#jaiihecj #aj #ca4hb #aj1cha 4#iiidh #a1jjj4ej 4#jcaghdfj #aa #dj4ab #h1bcd4j #a4bfjbj #gic4ef 4#jejedacj #ab #ej4ei #f1ebi4i #a4ehijj #fbi4cb 4#jhjcfdaj #ac #fc4gi #e1agh4d #b4jjcgj #dii4jf 4#abgghhjj #ad #hj4dd #d1ajf4h #b4ebffj #cie4gi 4#bjcahjjj #ae #aja4d #c1bef4g #c4ahfjj #cac4hg 4#cbcjgijj #af #abg4i #b1ehb4i #d4jagfj #bdh4ij 4#eacgcgjj #ag #afa4c #b1jdh4b #e4jffjj #aig4ci 4#hafhcijj #ah #bjc4d #a1fbd4c #f4chhjj #aef4ed #a4bihgfdjj ---------------------------------------- ----------------------- ,,carrying ,,capacity ,,of ,,wires ,,and ,,weight ---------------------------------------- ------------------------------ ,weight #a1jjj ft4 ,carrying capacity ,carrying capacity ,b4 ,s4 ,weatherproof ,weatherproof rubber cov4 ,gauge ,no4 7,pounds7 7,amperes7 7,amperes7 ---------------------------------------- ------------------------------ #jjjj #hjj #cab #age #jjj #fff #bfb #ade #jj #ejj #bbj #abj #j #cfc #ahe #ajj #a #cac #aef #ie #b #bej #aca #gj #c #bjj #aaj #fj #d #add #ib #ej #e #abe #gg #de #f #aje #fe #ce #g #hg #ee #cj #h #fi #df #be #aj #ej #cb #bj #ab #ca #bc #ae #ad #bb #af #aj #af #ad #h #e #ah #aa #e #c ---------------------------------------- ------------------------------ ,since two wires are required for electrical transmission1 the above formula is made simple by counting the distance only one way1 in feet1 and doubling the resistance constant1 #aj4f1 which1 for convenience is taken as #bb1 instead of #ba4b4 ,examples of ,transmission ,lines ,as an example1 let us say that ,farmer ,jones has installed a water-power electric plant on his brook1 #bjj yards distant from his house4 ,the generator is a #e kilowatt machine1 capable of producing #de amperes at #aaj volts pressure4 ,he has a #c horsepower motor1 drawing #bf amperes at full load2 he has #bj lights of varying capacities1 requiring #a1bjj watts1 or #aj amperes when all on2 and his wife uses irons1 toasters1 etc41 which amount to another #i or #aj amperes--say #de altogether4 ,the chances are that he will never use all of the apparatus at one time2 but for flexibility1 and his own satisfaction in not having to stop to think if he is overloading his wires1 he would like to be able to draw the full #de amperes if he wishes to4 ,he is willing to allow #e per cent loss in transmission4 ,what size wires will be necessary1 and what will they cost8 ,substituting these values in the above formula1 the result is3 ,answer3 #fjj #bb #de ------------- #ajh1jjj circular mills4 #e4e ,illustration3 ,transmission wire on glass insulator ,referring to the table1 ,no4 #j wire is #aje1ecd circular mills1 and is near enough2 so this wire would be used4 ,it would require #a1bjj feet1 which would weigh1 by the second table1 #dce4f pounds4 ,at #ai cents a pound1 it would cost #hb4gf4 ,farmer ,jones says this is more money than he cares to spend for transmission4 ,as a matter of fact1 he says1 he never uses his motor except in the daytime1 when his lights are not burning2 so the maximum load on his line at any one time would be #bf amperes1 not #de4 ,what size wire would he use in this instance8 ,substituting #bf for #de in the equation1 the result is #fa1cjj circular mills1 which corresponds to ,no4 #b wire4 ,it would cost #eg4jj4 ,now1 if ,farmer ,jones1 in an emergency1 wished to use his motor at the same time he was using all his lights and his wife was ironing and making toast--in other words1 if he wanted to use the #de amperes capacity of his dynamo1 how many volts would he lose8 ,to get this answer1 we change the formula about1 until it reads as follows3 ,distance in feet #bb amperes --------------------------------- ,number of volts lost circular mills ,substituting values1 we have1 in this case1 #fjj #bb #de_/ff1cgc 7,no4 #b7 #i volts1 nearly1 less than #aj per cent4 ,this is a very efficient line1 under the circumstances4 ,now if he is willing to lose #aj per cent on half-load1 instead of full load1 he can save still more money in line wire4 ,in that case 7as you can find by applying the formula again71 he could use ,no4 #e wire1 at a cost of #bh4ej4 ,he would lose #aa volts pressure drawing #bf amperes2 and he would lose #ah volts pressure drawing #de amperes1 if by any chance he wished to use full load4 ,in actual practice1 this dynamo would be regulated1 by means of the field resistance1 to register #aaj plus #aa volts1 or #aba volts at the switchboard to make up for the loss at half-load4 ,at full load1 his voltage at the end of the line would be #aba minus #ah1 or #ajc volts2 his motor would run a shade slower1 at this voltage1 and his lights would be slightly dimmer4 ,he would probably not notice the difference4 ,if he did1 he could walk over to his generating station1 and raise the voltage a further #g volts by turning the rheostat handle another notch4 ,illustration3 ,a barn-yard light ,thousands of plants can be located within #ajj feet of the house4 ,if ,farmer ,jones could do this1 he could use ,no4 #h wire1 costing #b4fb4 ,the drop in pressure would be #e4ii volts at full load--so small it could be ignored entirely4 ,in this case the voltmeter should be made to read #aaf volts at the switchboard1 by means of the rheostat4 ,if1 on the other hand1 this plant were #a1jjj feet away from the house and the loss #aj volts the size wire would be #a1jjj #bb #de --------------- #ii1jjj circular mills2 #aj a ,no4 #j wire comes nearest to this figure1 and its cost1 for #b1jjj feet1 at #ai cents a pound1 would be #acg4id4 ,a ,no4 #jjjj wire1 costing #bid4jj1 would give a #e per cent drop at full load4 ,in this case1 the cost of transmission can be reduced to a much lower figure1 by allowing a bigger drop at half-load1 with regulation at the switchboard4 ,thus1 a ,no4 #b wire here1 costing but #ie1 would be satisfactory in every way4 ,the loss at half-load would be about #i volts1 and the rheostat would be set permanently for #aai or #abj volts4 ,a modern dynamo can be regulated in voltage by over #be per cent in either direction1 without harm1 if care is taken not to overload it4 ,benefit of ,higher ,voltages ,if ,farmer ,jones' plant is a half of a mile away from the house1 he faces a more serious proposition in the way of transmission4 ,say he wishes to transmit #bf amperes with a loss of #aj volts4 ,what size wire will be necessary8 #bfdj #bb #bf ,thus3 -------------- #aea1jjj circular mills4 #aj ,a ,no4 #jjj wire is nearest this size1 and #e1bhj feet of it would cost over #fej4jj4 ,this cost would be prohibitive4 ,if1 however1 he installed a #bbj-volt dynamo--at no increase in cost--then he would have to transmit only a half of #bf amperes1 or #ac amperes1 and he could allow #bb volts loss1 counting #aj per cent4 ,in this case1 the problem would work out as follows3 #bfdj #bb #ac -------------- #cd1cbj circular mills1 #bb or approximately a ,no4 #e wire which1 at #ai cents a pound1 would cost #abj4fe4 ,install a #eej-volt generator1 instead of a #bbj-volt machine and the amperes necessary would be cut to #e4b1 and the volts lost would be raised to #ee4 ,in this case a ,no4 #ab wire would carry the current2 but since it would not be strong enough for stringing on poles1 a ,no4 #h wire would be used1 costing about #fc4 ,it will be readily seen from these examples how voltage influences the efficiency of transmission4 ,current generated at a pressure in excess of #eej volts is not to be recommended for farm plants unless an expert is in charge4 ,a safer rule is not to exceed #bbj volts1 for while #eej volts is not necessarily deadly1 it is dangerous4 ,when one goes into higher voltages1 it is necessary to change the type of dynamo to alternating current1 so that the current can be transformed to safe voltages at the point where it is used4 ,since only the occasional farm plant requires a high-tension system1 the details of such a plant will not be gone into here4 ,in transmitting the electric current over miles of territory1 engineers are accustomed to figure #a1jjj volts for each mile4 ,since this is a deadly pressure1 it should not be handled by any one not an expert1 which1 in this case1 the farmer is not4 ,over-,compounding the ,generator ,one can absorb the loss in transmission frequently1 by over-compounding the machine4 ,in describing the compound machine1 in ,chapter ,five1 it is shown that the usual compound dynamo on the market is the so-called flat-compounded type4 ,in such a dynamo1 the voltage remains constant at the switchboard1 from no load to full load1 allowing for a slight curve which need not be taken into account4 ,now1 by adding a few more turns to the series wires on the field coils of such a dynamo1 a machine is to be had which gradually raises its voltage as the load comes on in increasing volume4 ,thus1 one could secure such a machine1 which would begin generating at #aaj volts1 and would gradually rise to #aej at full load4 ,yet the voltage would remain constant at the point of use1 the excess being absorbed in transmission4 ,a machine of this type can be made to respond to any required rise in voltage4 ,as an example of how to take advantage of this very valuable fact1 let us take an instance3 ,say that ,farmer ,jones has a transmission line #a1jjj feet long strung with ,no4 #g copper wire4 ,this #b1jjj feet of wire would introduce a resistance of one ohm in the circuit4 ,that is1 every ampere of current drawn at his house would cause the working voltage there to fall one volt4 ,if he drew #bf amperes1 the voltage would fall1 at the house1 #bf volts4 ,if his switchboard voltage was set at say #abj1 the voltage at his house1 at #bf amperes of load1 would fall to #id volts1 which would cause his lights to dim considerably4 ,it would be a very unsatisfactory transmission line1 with a flat-compounded dynamo4 ,on the other hand1 if his dynamo was over-compounded #be per cent--that is1 if it gained #bh volts from no load to full load1 the system would be perfect4 ,in this case1 the dynamo would be operated at #aaj volts pressure at the switchboard with no load4 ,at full load the voltmeter would indicate #aaj plus #bf1 or #acf volts4 ,the one or two lights burned at the power plant would be subject to a severe strain2 but the #ej or #ajj lights burned at the house and barn would burn at constant voltage1 which is very economical for lamps4 ,the task of over-compounding a dynamo can be done by any trained electrician4 ,the farmer himself1 if he progresses far enough in his study of electricity1 can do it4 ,it is necessary to remove the top or series winding from the field coils4 ,count the number of turns of this wire to each spool4 ,then procure some identical wire in town and begin experimenting4 ,say you found four turns of field wire to each spool4 ,now wind on five1 or six1 being careful to wind it in the same direction as the coils you removed and connect it in the same way4 ,if this additional number of turns does not raise the voltage enough1 in actual practice1 when the dynamo is running from no load to full load1 add another turn or two4 ,with patience1 the task can be done by any careful mechanic4 ,the danger is in not winding the coils the same way as before1 and getting the connections wrong4 ,to prevent this mistake1 make a chart of the series coils as you take them off4 ,to make the task of over-compounding your own dynamo even more simple1 write to the manufacturers1 giving style and factory number of your machine4 ,tell them how much voltage rise you wish to secure1 and ask them how many turns of series wire should be wound on each spool in place of the old series coil4 ,they could tell you exactly1 since they have mathematical diagrams of each machine they make4 ,avoid overloading an over-compounded machine4 ,since its voltage is raised automatically1 its output in watts is increased a similar amount at the switchboard1 and1 for a given resistance1 its output in amperes would be increased the same amount1 as can be ascertained by applying ,ohm's ,law4 ,your ammeter is the best guide4 ,your machine is built to stand a certain number of amperes1 and this should not be exceeded in general practice4 ,,chapter ,,viii ,,wiring ,,the ,,house ,the insurance code--,different kinds of wiring described--,wooden moulding cheap and effective--,the distributing panel--,branch circuits--,protecting the circuits--,the use of porcelain tubes and other insulating devices--,putting up chandeliers and wall brackets--,multiple connections--,how to connect a wall switch--,special wiring required for heat and power circuits--,knob and cleat wiring1 its advantages and drawbacks4 ,the task of wiring your house is a simple one1 with well-defined rules prescribed by your insurance company4 ,electricity1 properly installed1 is much safer than oil lamps--so much so indeed that insurance companies are ready to quote especial rates4 ,but they require that the wiring be done in accordance with rules laid down by their experts1 who form a powerful organization known as the ,national ,board of ,fire ,underwriters4 ,ask your insurance agent for a copy of the code rules4 ,danger of fire from an electric current comes from the short circuit1 partial or complete2 and it is against this danger that the rules guard one4 ,the amount of electricity flowing through a short circuit is limited only by the fuse protecting that line2 and since there is no substance known that can withstand the heat of the electric arc1 short circuits must be guarded against4 ,happily the current is so easily controlled that the fire hazard is eliminated entirely--something which cannot be done with oil lamps4 ,in house-wiring for farm plants1 the wire should be rubber-covered1 and not smaller than ,no4 #ad ,b4 ,s4 gauge4 ,this is the wire to use on all lamp circuits4 ,it costs about #j4he cents per #ajj feet4 ,there are four kinds of wiring permitted1 under the insurance code3 7#a7 ,flexible armoured cable3 ,this consists of two-wire cable1 protected with a covering of flexible steel4 ,it is installed out of sight between the walls1 and provides suitable outlets for lamps1 etc41 by means of metal boxes set flush with the plaster4 ,it is easily installed in a house being built1 but requires much tearing down of plaster for an old house4 ,since its expense prohibits it in the average farm house1 this system will not be described in detail here4 7#b7 ,rigid and flexible conduit3 ,as the name implies this system consists of iron pipe1 in connection with flexible conduit1 run between the walls4 ,it differs from the above system1 in that the pipes with their fittings and outlet boxes are installed first1 and the wires are then fished through them4 ,duplex wires--the two wires of the circuit woven in one braid--are used2 and a liberal amount of soapstone1 and occasionally kerosene1 are used to make the wires slip easily into place4 ,this is the most expensive system1 and the best2 but it is difficult to install it in an old house without tearing down a good deal of plaster4 ,it has the advantage of being absolutely waterproof and fireproof4 7#c7 ,wooden moulding3 ,this is simply moulding1 providing two raceways for the insulated wires to run in1 and covered with a capping4 ,it is nailed or screwed firmly to the wall1 on top of the plaster2 and when the wires have been installed in their respective slots and the capping tacked on1 the moulding is given a coat of paint to make it in harmony with the other moulding in the room4 ,this system is cheap1 safe1 and easily installed1 and will be described in detail here4 ,illustration3 ,detail of wooden moulding 7#d7 ,open wiring3 ,in open wiring1 the wires are stretched from one support to another 7such as beams7 and held by means of porcelain cleats1 or knobs4 ,it is the simplest to install2 but it has the objection of leaving the wires unprotected1 and is ugly4 ,it is very satisfactory in barns or out-buildings however4 ,the ,distributing ,panel ,the first point to consider in wiring a house with wooden moulding is the distribution board4 ,it should be located centrally1 on the wall near the ceiling1 so as to be out of ordinary reach4 ,it consists of a panel of wood--though fireproof material is better--firmly screwed to the wall1 and containing in a row1 the porcelain cut-outs1 as shown in the cut1 from which the various branch circuits are to be led4 ,each cut-out provides for two branch circuits2 and each branch contains receptacles for two plug fuses4 ,these fuses should be of #f amperes each4 ,the ,insurance ,code limits the amount of electricity that may be drawn on any branch lamp circuit to #ffj watts2 and these fuses protect the circuit from drafts beyond this amount4 ,illustration3 ,porcelain cut-out and plug fuse ,the mains1 leading from the entrance switch1 as shown in the diagram1 to the panel board1 should be of the same size as the transmission wire itself1 and rubber-covered4 ,these mains terminate at the distributing board4 ,they are connected to the terminals of the cut-outs by means of heavy brass screws4 ,wire ,joints ,illustration3 ,examples of cleat and knob wiring1 #a1 #b1 #c2 wire joints1 #d2 flexible armoured conductor1 #e ,the branch circuits are1 as has been said1 of ,no4 #ad rubber-covered wire1 running concealed in wooden moulding4 ,all joints or splices in this wire are made1 as shown in the illustration1 by first scraping the wires bright1 and fastening them stoutly together4 ,this joint is then soldered1 to make the connection electrically perfect4 ,soft solder is used1 with ordinary soldering salts4 ,there are several compounds on the market1 consisting of soft solder in powder form1 ready-mixed with flux4 ,coat the wire joint with this paste and apply the flame of an alcohol lamp4 ,the soldered joint is then covered with rubber tape1 and over this ordinary friction tape is wound on4 ,a neat joint should not be larger than the diameter of the wire before insulation is removed4 ,branch ,circuits ,first1 make a diagram of your rooms and indicate where you wish lamps1 or outlets for other purposes4 ,since wooden moulding can be run across ceilings1 and up or down walls1 lamps may be located in places where they are out of the way4 ,in planning the circuit1 remember that you will want many outlets in handy places on the walls1 from which portable cords will convey current to table lamps1 to electric irons and toasters and other handy devices which can be used on the lamp circuit4 ,these outlets are made of porcelain1 in two pieces4 ,one piece is merely a continuation of the moulding itself2 and the other is a cap to connect permanently to the end of the lamp or iron cord1 which may be snapped into place in a second4 ,since there are a great many designs of separable current taps on the market1 it is well to select one design and stick to it throughout the house1 so that any device can be connected to any outlet4 ,the code permits #ffj watts on each circuit4 ,this would allow #ab lamps of #ee watts each4 ,it is well to limit any one circuit to #f lamps2 this will give leeway for the use of small stoves1 irons1 toasters1 etc4 without overloading the circuit and causing a fuse to blow4 ,having installed your distributing board1 with its cut-outs1 figure out the course of your first branch circuit4 ,let us say it will provide lights and outlets for the dining room and living room4 ,it will be necessary to run the wires through the partitions or floors in several places4 ,for this purpose porcelain tubes should be used1 costing one to three cents each4 ,knock holes in the plaster at the determined point1 insert the tubes so they project #c_/d inch on each side1 and fill up the ragged edge of the hole neatly with plaster4 ,illustration3 ,the distributing panel ,when all the tubes have been set in place1 begin laying the moulding4 ,run it in a straight line1 on the wall against the ceiling wherever possible1 mitering the joints neatly4 ,whenever it is necessary to change the run from the ceiling to the wall and a miter cannot be made1 the wires should be protected in passing from one slot to the other by being enclosed in non-metallic flexible conduit1 called circular loom4 ,in running wooden moulding1 avoid brick walls liable to sweat or draw dampness2 keep away from places where the heat of a stove might destroy the rubber insulation of the wires2 do not pass nearer than six inches to water pipes when possible--and when it is necessary to pass nearer than this1 the wooden moulding should pass above the pipe1 not below it1 with at least an inch of air space intervening1 thus avoiding dampness from sweating of pipes4 ,illustration3 ,snap switch connections ,places where chandeliers or wall bracket lamps are to be installed permanently are fitted with wooden terminal blocks1 which fit over the moulding and flush with the plaster4 ,these1 after holes have been bored in them for the wires1 and the wires drawn through1 should be screwed firmly to the wall or ceiling1 always choosing a joist or beam for support4 ,then a crow's-foot1 or tripod of iron1 tapped and threaded for iron pipe1 is screwed to the terminal block4 ,the iron pipe of the chandelier or wall bracket is then screwed home in this crow's-foot4 ,do not begin stringing wires until all the moulding of the circuit has been laid4 ,then thread the wires through the wall or floor tubes and lay them in their respective slots4 ,if trouble be found making them stay in place before the capping is put on1 small tacks may be driven into the moulding beside them to hold them4 ,when a terminal block is reached1 a loop is made of each wire1 through the hole cut in the block1 if the circuit is to continue in the same direction4 ,if it is to end there1 the two wires are drawn through taut1 and cut off at a length of #e or #f inches4 ,these end wires1 or loops1 are then scraped bare and spliced to the two wires coming out of the chandelier or wall bracket4 ,this joint is then soldered and covered with tape1 and the shell of the chandelier is screwed into place1 covering the joint4 ,illustration3 ,detail of wooden moulding ,if the moulding is run along the walls flush with the ceiling1 as is usual1 a branch is made for a wall light1 or wall tap1 by means of a porcelain ,t1 or branch-block1 which provides the means for running the circuit at right angles to itself without letting the wires come in contact with each other where they cross4 ,separable current taps should be installed in handy places on all circuits1 so that small heating devices may be used without removing the lamps from their sockets4 ,the two wires are bared for half an inch where they run through these current taps1 and are fastened by means of brass screws4 ,multiple ,connections ,all electric devices for this installation--lamps1 irons1 vacuum cleaners1 motors--must be connected across the circuit--that is1 bridged1 from one wire to the other4 ,this is called multiple1 or shunt connection4 ,there is only one exception to it1 in wiring the house4 ,that one exception is installing a wall switch1 the ordinary snap switch4 ,since this wall switch1 is1 in effect1 merely an instrument1 which opens or closes a circuit1 it should be connected to only one wire1 which is cut to provide two ends for the screw connections in the switch4 ,when a moulding branch is run down from the ceiling to some convenient spot for a snap switch 7with which to turn the lights of a room on or off71 a porcelain ,t is not used4 ,all that is necessary to do is to loop the bottom wire of the circuit down through the branch moulding1 and connect it to the switch at a terminal block1 or porcelain base4 ,in wiring lamp fixtures1 ,no4 #ad rubber-covered wire will usually prove too large4 ,for this purpose1 ,no4 #ah may be used1 with one lamp to each loop4 ,hanging lamps may not be supported by electric lamp cord itself1 if there is more than one lamp in the cluster1 because the weight is apt to break the electrical connections4 ,in such a case1 the lamp should be supported by a chain1 and the twisted cord conveying current to the electric bulbs1 is woven in the links of the chain4 ,for the pantry1 kitchen1 woodshed1 barn1 etc41 a single hanging lamp may be suspended from a fielding rosette1 as shown in the cut1 provided a single knot is tied inside both the rosette and the lamp socket1 to make it secure4 ,this makes a very cheap fixture4 ,the rosette of porcelain will cost #ae cents2 the lamp socket #bj cents1 and the lamp cord suspending the lamp and carrying the current will cost #a-a_/b cents a foot2 while a tin shade will cost another #ae cents4 ,illustration3 ,detail of simple hanging lamp supported by rosette ,official ,inspection ,in all communities1 your insurance agent must inspect and pass your wiring before you are permitted to throw the main switch and turn on the electricity4 ,frequently they require that the moulding be left uncapped1 until they have inspected it4 ,if you have more than #ffj watts in lamps to a circuit2 if your joints are not soldered and well taped2 if the moulding is used in any concealed or damp place1 the agent is liable to condemn your work and refuse permission to turn on the electricity4 ,however the rules are so clearly defined that it is difficult to go wrong2 and a farmer who does his own wiring and takes pride in its appearance is more apt to be right than a professional electrician who is careless at his task4 ,after the work has been passed1 tack on the moulding capping1 with brads1 and paint the moulding to match the woodwork4 ,wooden moulding wiring is perfectly satisfactory if properly installed4 ,it is forbidden in many large cities1 because of the liability of careless workmanship4 ,it should never be installed in damp places1 or out of sight4 ,if the work is well done1 the system leaves nothing to be desired2 and it has the additional advantage of being cheap1 and easily done by any farmer who can use carpenter tools4 ,farmers with moulding machinery can make their own moulding4 ,the code prescribes it shall be of straight-grained wood2 that the raceways for the wires shall be separated by a tongue of wood one-half inch wide2 and that the backing shall be at least #c_/h inch thick4 ,it must be covered1 inside and out1 with at least two coats of moisture-repellant paint4 ,it can be had ready-made for about #b cents a foot4 ,special ,heating ,circuits ,if one plans using electricity for heavy-duty stoves1 such as ranges and radiators1 it is necessary to install a separate heating circuit4 ,this is the best procedure in any event1 even when the devices are all small and suited to lamp circuits4 ,the wire used can be determined by referring to the table for carrying capacity1 under the column headed rubber-covered4 ,a stove or range drawing #dj amperes1 would require a ,no4 #d wire1 in moulding4 ,a good plan is to run the heating circuit through the basement1 attaching it to the rafters by means of porcelain knobs4 ,branches can then be run up through the floor to places where outlets are desired4 ,such a branch circuit should carry fuses suitable to the allowed carrying capacity of the wire4 ,knob and ,cleat ,wiring ,knob and cleat wiring1 such as is used extensively for barns and out-buildings1 requires little explanation4 ,the wires should not be closer than #b-a_/b inches in open places1 and a wider space is better4 ,the wires should be drawn taut1 and supported by cleats or knobs at least every four feet4 ,in case of branch circuits1 one wire must be protected from the other it passes by means of a porcelain tube4 ,it should never be used in damp places1 and should be kept clear of dust and litter1 and protected from abrasion4 ,illustration3 ,knob and cleat wiring ,knob and tube wiring is frequently used in houses1 being concealed between walls or flooring4 ,in this case1 the separate wires are stretched on adjoining beams or rafters1 and porcelain tubes are used1 in passing through cross beams4 ,for a ceiling or wall outlet1 a spliced branch is passed through the plaster by means of porcelain tubes or flexible loom4 ,wires from the house to the barn should be uniform with transmission wires4 ,at the point of entry to buildings they must be at least six inches apart1 and must take the form of the drop loop as shown in the illustration4 ,a double-pole entrance switch must be provided1 opening downward1 with a double-pole fuse4 ,in passing over buildings wires must not come closer than #g feet to flat roofs1 or one foot to a ridge roof4 ,feed-wires for electric motors should be determined from the table of safe carrying capacities1 and should be of liberal size4 ,,chapter ,,ix ,,the ,,electric ,,plant ,,at ,,work ,direct-connected generating sets--,belt drive--,the switchboard--,governors and voltage regulators--,methods of achieving constant pressure at all loads3 ,over-compounding the dynamo2 ,a system of resistances2 7,a home-made electric radiator72 ,regulating voltage by means of the rheostat--,automatic devices--,putting the plant in operation4 ,dynamos may be connected to water wheels either by means of a belt1 or the armature may spin on the same shaft as the water wheel itself4 ,the latter is by far the more desirable way1 as it eliminates the loss of power through shafting and belting1 and does away altogether with the belts themselves as a source of trouble4 ,an installation with the water wheel and armature on the same shaft is called a direct-connected set and is of almost universal use in large power plants4 ,to be able to use such a direct-connected set1 the dynamo must be designed to develop its full voltage when run at a speed identical with that of the water wheel4 ,that is1 if the dynamo is wound to be run at a speed of #hjj revolutions per minute1 it must be driven by a water wheel which runs at this speed and can be governed within narrow limits4 ,small impulse wheels running under great heads attain high speed1 and for such wheels it is possible to obtain a suitable dynamo at low cost4 ,for instance1 a #ab-;inch impulse wheel1 running under a #bjj-;foot head will develop #f-c_/d horsepower when running at a speed of #hge revolutions per minute4 ,a dynamo for direct coupling to such a wheel should have a rated speed within #e per cent of #hge r4p4m42 and1 as generators of this speed are to be had from the stock of almost all manufacturers1 there would be no extra charge4 ,when it comes to the larger wheels1 however1 of the impulse type1 or to turbines operating under their usual head the question becomes a little more difficult4 ,in such cases1 the speed of the water wheel will vary from #aej revolutions per minute1 to #djj1 which is slow speed for a small dynamo4 ,as a general rule1 the higher the speed of a dynamo1 the lower the cost2 because1 to lower the speed for a given voltage1 it is necessary either to increase the number of conductors on the armature1 or to increase the number of field coils1 or both4 ,that means a larger machine1 and a corresponding increase in cost4 ,in practice1 in large plants1 with alternating-current machines it has become usual to mount the field magnets on the shaft1 and build the armature as a stationary ring in whose air space the field coils revolve4 ,this simplifies the construction of slow-speed1 large-output dynamos4 ,such a machine1 however1 is not to be had for the modest isolated plant of the farmer with his small water-power4 ,illustration3 ,instantaneous photograph of high-pressure water jet being quenched by buckets of a tangential wheel ,illustration3 ,a tangential wheel1 and a dynamo keyed to the same shaft--the ideal method for generating electricity4 ,the centrifugal governor is included on the same base ,dynamos can be designed for almost any waterwheel speed1 and1 among small manufacturers especially1 there is a disposition to furnish these special machines at little advance in price over their stock machines4 ,frequently it is merely a matter of changing the winding on a stock machine4 ,the farmer himself1 in many cases1 can re-wind an old dynamo to fit the speed requirements of a direct-connected drive if the difference is not too great4 ,all that would be necessary to effect this change would be to get the necessary winding data from the manufacturer himself1 and proceed with the winding4 ,this data would give the gauge of wire and the number of turns required for each spool of the field magnets2 and the gauge of wire and number of turns required for each slot in the armature4 ,the average boy who has studied electricity 7and there is something about electricity that makes it closer to the boy's heart than his pet dog7 could do this work4 ,the advantages of direct drive are so many that it should be used wherever possible4 ,when direct drive cannot be had1 a belt must be used1 either from a main shaft1 or a countershaft4 ,the belt must be of liberal size1 and must be of the endless variety--with a scarfed joint4 ,leather belt lacing1 or even the better grades of wire lacing1 unless very carefully used1 will prove unsatisfactory4 ,the dynamo feels every variation in speed1 and this is reflected in the lights4 ,there is nothing quite so annoying as flickering lights4 ,usually this can be traced to the belt connections4 ,leather lacing forms a knot which causes the lights to flicker at each revolution of the belt4 ,the endless belt does away with this trouble4 ,most dynamos are provided with sliding bases1 by which the machine can be moved one way or another a few inches1 to take up slack in the belt4 ,to take advantage of this1 the belt must be run in a horizontal line1 or nearly so4 ,vertical belting is to be avoided4 ,the dynamo is mounted on a wooden base1 in a dry location where it is protected from the weather1 or dampness from any source4 ,it must be mounted firmly1 to prevent vibration when running up to speed2 and the switchboard should occupy a place within easy reach4 ,wires running from the dynamo to the switchboard should be protected from injury1 and must be of ample size to carry the full current of the machine without heating4 ,a neat way is to carry them down through the flooring through porcelain tubes1 thence to a point where they can be brought up at the back of the switchboard4 ,if there is any danger of injury to these mains they may be enclosed in iron pipe4 ,keep the wires out of sight as much as possible1 and make all connections on the back of the switchboard4 ,the ,switchboard ,illustration3 ,connecting switchboard instruments ,the switchboard is constructed of some fireproof material1 preferably slate or marble4 ,when the cost of this material is an item to consider1 build a substantial wooden frame for your switchboard4 ,you can then screw asbestos shingles to this to hold the various instruments and with a little care such a switchboard can be made to look business-like1 and it is fully as serviceable as the more expensive kind4 ,the switchboard instruments have already been described briefly4 ,they consist of a voltmeter 7to measure voltage72 an ammeter 7to measure the strength of the current drawn1 in amperes71 a rheostat 7to regulate the voltage of the machine to suit the individual requirements72 and the usual switches and fuses4 ,the main switch should be so wired that when open it will throw all the current off the line1 but still leave the field coils1 the voltmeter1 and the switchboard lamp in circuit4 ,the main-switch fuses should have a capacity about #ej per cent in excess of the full load of the dynamo4 ,if the machine is rated for #ej amperes1 #ge-;ampere fuses should be installed4 ,this permits throwing on an overload in an emergency2 and at the same time guards against a short circuit4 ,if the capacity of the machine is under #cj amperes1 plug fuses1 costing #c cents each1 can be used4 ,if it is above this capacity1 cartridge fuses1 costing a little more1 are required4 ,a supply of these fuses should be kept handy at all times4 ,governors and ,voltage ,regulators ,illustration3 ,a centrifugal governor 7,courtesy of the ,c4 ,p4 ,bradway ,company1 ,west ,stafford1 ,conn47 ,the necessity for water wheel governors will vary with conditions4 ,as a general rule1 it may be said that reaction turbines working under a low head with a large quantity of water do not require as much governing as the impulse wheel1 working under high heads with small quantities of water4 ,when governing is necessary at all1 it is because the prime mover varies in speed from no load to full load4 ,planning one's plant with a liberal allowance of power--two water horsepower to one electrical horsepower is liberal--reduces the necessity of governors to a minimum4 ,as an instance of this1 the plant described in some detail in ,chapters ,one and ,six of this volume1 runs without a governor4 ,however1 a surplus of water-power is not usual4 ,generally plants are designed within narrow limits2 and then the need of a governor becomes immediately apparent4 ,there are many designs of governors on the market1 the cheapest being of the centrifugal type1 in which a pair of whirling balls are connected to the water wheel gate by means of gears1 and open or close the gate as the speed lowers or rises4 ,constant speed is necessary because voltage is directly dependent on speed4 ,if the speed falls #be per cent1 the voltage falls likewise2 and a plant with the voltage varying between such limits would be a constant source of annoyance1 as well as expense for burned-out lamps4 ,since constant voltage is the result aimed at by the use of a governor1 the same result can be attained in other ways1 several of which will be explained here briefly4 ,over-,compounding 7#a7 ,over-compounding the dynamo4 ,this is simple and cheap1 if one buys the right dynamo in the first instance2 or if he can do the over-compounding himself1 by the method described in the concluding paragraphs of ,chapter ,seven4 ,if it is found that the speed of the water wheel drops #be per cent between no load and full load1 a dynamo with field coils over-compounded to this extent would give a fairly constant regulation4 ,if you are buying a special dynamo for direct drive1 your manufacturer can supply you with a machine that will maintain constant voltage under the normal variations in speed of your wheel4 ,a ,system of ,resistances 7#b7 ,constant load systems4 ,this system provides that the dynamo shall be delivering a fixed amount of current at all times1 under which circumstances the water wheel would not require regulation1 as the demands on it would not vary from minute to minute or hour to hour4 ,this system is very simply arranged4 ,it consists of having a set of resistances to throw into the circuit1 in proportion to the amount of current used4 ,let us say1 as an example1 that a #ej-;ampere generator is used at a pressure of #aaj volts2 and that it is desirable to work this plant at #hj per cent load1 or #dj amperes current draft4 ,when all the lights or appliances were in use1 there would be no outside resistance in the circuit4 ,when none of the lights or appliances were in use 7as would be the case for many hours during the day7 it would be necessary to consume this amount of current in some other way--to waste it4 ,a resistance permitting #dj amperes of current to flow1 would be necessary4 ,of what size should this resistance be8 ,the answer is had by applying ,ohm's ,law1 explained in ,chapter ,five4 ,the ,law in this case1 would be read ,r ,e_/,c4 ,therefore1 in this case ,r #aaj_/dj #b-c_/d ohms resistance1 would be required1 switched across the mains1 to keep the dynamo delivering its normal load4 ,the cheapest form of this resistance would be iron wire4 ,in place of iron wire1 ,german silver wire could be used4 ,german silver wire is to be had cheaply1 and is manufactured in two grades1 #ah and #cj1 with a resistance respectively #ah and #cj times that of copper for the same gauge4 ,nichrome wire has a resistance #fj times that of copper2 and manganin wire has a resistance #fe times that of copper1 of the same gauge4 ,first figure the number of feet of copper wire suitable for the purpose4 ,allowing #ejj circular mills for each ampere1 the gauge of the wire should be #dj #ejj #bj1jjj circular mills1 or approximately ,no4 #g ,b4 ,s4 gauge4 ,how many feet of ,no4 #g copper wire would give a resistance of #b-c_/d ohms8 ,referring to the copper wire table1 we find that it requires #bjjf4b of ,no4 #g wire to make one ohm4 ,then #b-c_/d ohms would require #e1eag feet4 ,since #cj per cent ,german silver wire is approximately #cj times the resistance of copper1 a ,no4 #g ,german silver wire1 for this purpose1 would be #a_/cj the length of the copper wire1 or #ahf feet4 ,if nichrome wire were used1 it would be #a_/fjth the length of copper for the same gauge1 or #ic feet4 ,this resistance wire can be wound in spirals and made to occupy a very small space4 ,as long as it is connected in circuit1 the energy of the dynamo otherwise consumed as light would be wasted as heat4 ,this heat could be utilized in the hot water boiler or stove when the lights were turned off4 ,in actual practice1 however1 the resistance necessary to keep the dynamo up to full load permanently1 would not be furnished by one set of resistance coils4 ,each lamp circuit would have a set of resistance coils of its own4 ,a double-throw switch would turn off the lamps and turn on the resistance coils1 or vice versa4 ,let us say a lamp circuit consisted of #f carbon lamps1 of #af candlepower each4 ,it would consume #f #a_/b ampere1 or #c amperes of current1 and interpose a resistance of #cf4f ohms--say #cg ohms4 ,three amperes would require a wire of at least #a1ejj circular mills in area for safety4 ,this corresponds to a ,no4 #ah wire4 ,a ,no4 #ah copper wire interposes a resistance of one ohm1 for each #aef4e feet length4 ,for #cg ohms1 #e1gij feet would be required1 for copper wire1 which of course would be impractical4 ,dividing by #cj gives #aic feet for #cj ,german silver wire2 and dividing by #fj gives #if feet of nichrome wire of the same gauge4 ,it is simple to figure each circuit in this way and to construct resistance units for each switch4 ,since the resistance units develop considerable heat1 they must be enclosed and protected4 ,a ,home-made ,stove or ,radiator ,while we are on the subject of resistance coils it might be well here to describe how to make stoves for cooking1 and radiators for heating the house1 at small expense4 ,these stoves consist merely of resistances which turn hot--a dull red--when the current is turned on4 ,iron wire1 ,german silver wire1 or the various trade brands of resistance wire1 of which nichrome1 calido1 and manganin are samples1 can be used4 ,in buying this wire1 procure the table of resistance and carrying capacity from the manufacturers4 ,from this table you can make your own radiators to keep the house warm in winter4 ,iron wire has the disadvantage of oxidizing when heated to redness1 so that it goes to pieces after prolonged use4 ,it is cheap1 however1 and much used for resistance in electrical work4 ,let us say we wish to heat a bathroom1 a room #f #h1 and #h feet high--that is a room containing #chd cubic feet of air space4 ,allowing #b watts for each cubic foot1 we would require #gfh watts of current1 or practically #g amperes at #aaj volts4 ,what resistance would be required to limit the current to this amount8 ,apply ,ohm's ,law1 as before1 and we have ,r equals ,e divided by ,c1 or ,r equals #aaj divided by #g1 which is #ae4g ohms4 ,forty-two feet of ,no4 #bj ,german silver wire would emit this amount of heat and limit the current output to #g amperes4 ,in the ,far ,west1 it is quite common1 in the outlying district1 to find electric radiators made out of iron pipe covered with asbestos1 on which the requisite amount of iron wire is wound and made secure4 ,this pipe is mounted in a metal frame4 ,or the frame may consist of two pipes containing heating elements2 and a switch1 in this case1 is so arranged that either one or two heating elements may be used at one time1 according to the weather4 ,an ingenious mechanic can construct such a radiator1 experimenting with the aid of an ammeter to ascertain the length of wire required for any given stove4 ,regulating ,voltage at ,switchboards ,the voltage of any given machine may be regulated1 within wide limits1 by means of the field rheostat on the switchboard4 ,a dynamo with a rated speed of #a1ejj revolutions per minute1 for #aaj volts1 will actually attain this voltage at as low as #a1bjj r4p4m4 if all the regulating resistance be cut out4 ,you can test this fact with your own machine by cutting out the resistance from the shunt field entirely1 and starting the machine slowly1 increasing its speed gradually1 until the voltmeter needle registers #aaj volts4 ,then measure the speed4 ,it will be far below the rated speed of your machine4 ,if1 on the other hand1 the speed of such a machine runs up to #b1ejj or over--that is1 an excess of #fg--the voltage would rise proportionally1 unless extra resistance was cut in4 ,by cutting in such resistance--by the simple expedient of turning the rheostat handle on the switchboard1--the field coils are so weakened that the voltage is kept at the desired point in spite of the excessive speed of the machine4 ,excessive speeds are to be avoided1 as a rule1 because of mechanical strain4 ,but within a wide range1 the switchboard rheostat can be used for voltage regulation4 ,as it would be a source of continual annoyance to have to run to the switchboard every time the load of the machine was varied greatly this plan would not be practical for the isolated plant1 unless the rheostat could be installed1--with a voltmeter--in one's kitchen4 ,this could be done simply by running a small third wire from the switchboard to the house4 ,then1 when the lights became dim from excessive load1 a turn of the handle would bring them back to the proper voltage2 and when they flared up and burned too bright1 a turn of the handle in the opposite direction would remedy matters4 ,by this simple arrangement1 any member of the family could attend to voltage regulation with a minimum of bother4 ,automatic ,devices ,there are several automatic devices for voltage regulation at the switchboard on the market4 ,these consist usually of vibrator magnets or solenoids1 in which the strength of the current1 varying with different speeds1 reacts in such a way as to regulate field resistance4 ,such voltage regulators can be had for #dj or less1 and are thoroughly reliable4 99 99 99 99 99 ,to sum up the discussion of governors and voltage regulators3 ,if you can allow a liberal proportion of water-power1 and avoid crowding your dynamo1 the chances are you will not need a governor for the ordinary reaction turbine wheel4 ,start your plant1 and let it run for a few days or a few weeks without a governor1 or regulator4 ,then if you find the operation is unsatisfactory1 decide for yourself which of the above systems is best adapted for your conditions4 ,economy as well as convenience will affect your decision4 ,the plant which is most nearly automatic is the best2 but by taking a little trouble and giving extra attention1 a great many dollars may be saved in extras4 ,starting the ,dynamo ,you are now ready to put your plant in operation4 ,your dynamo has been mounted on a wooden foundation1 and belted to the countershaft1 by means of an endless belt4 ,see that the oil cups are filled4 ,then throw off the main switch and the field switch at the switchboard2 open the water gate slowly1 and occasionally test the speed of the dynamo4 ,when it comes up to rated speed1 say #a1ejj per minute1 let it run for a few minutes1 to be sure everything is all right4 ,having assured yourself that the mechanical details are all right1 now look at the voltmeter4 ,it is probably indicating a few volts pressure1 from #d to #h or #aj perhaps4 ,this pressure is due to the residual magnetism in the field cores1 as the field coils are not yet connected4 ,if by any chance1 the needle does not register1 or is now back of #j1 try changing about the connections or the voltmeter on the back of the switchboard4 ,now snap on the field switch4 ,instantly the needle will begin to move forward1 though slowly2 and it will stop4 ,turn the rheostat handle gradually2 as you advance it1 the voltmeter needle will advance4 ,finally you will come to a point where the needle will indicate #aaj volts4 ,if you have designed your transmission line for a drop of #e volts at half-load1 advance the rheostat handle still further1 until the needle points to #aae volts4 ,let the machine run this way for some time4 ,when assured all is right1 throw on the main switch1 and turn on the light at the switchboard4 ,then go to the house and gradually turn on lights4 ,come back and inspect the dynamo as the load increases4 ,it should not run hot1 nor even very warm1 up to full load4 ,its brushes should not spark1 though a little sparking will do no harm4 ,your plant is now ready to deliver current up to the capacity of its fuses4 ,see that it does not lack good lubricating oil1 and do not let its commutator get dirty4 ,the commutator should assume a glossy chocolate brown color4 ,if it becomes dirty1 or the brushes spark badly1 hold a piece of fine sandpaper against it4 ,never use emery paper6 ,if1 after years of service1 it becomes roughened by wear1 have it turned down in a lathe4 ,occasionally1 every few weeks1 say1 take the brushes out and clean them with a cloth4 ,they will wear out in the course of time and can be replaced for a few cents each4 ,the bearings may need replacing after several years' continuous use4 ,otherwise your electric plant will take care of itself4 ,keep it up to speed1 and keep it clean and well oiled4 ,never shut it down unless you have to4 ,in practice1 dynamos run week after week1 year after year1 without stopping4 ,this one1 so long as you keep it running true to form1 will deliver light1 heat and power to you for nothing1 which your city cousin pays for at the rate of #aj cents a kilowatt-hour4 ,,part ,,iii ,,gasoline ,,engines1 ,,windmills1 ,,etc4 ,,the ,,storage ,,batteries ,,chapter ,x ,,gasoline ,,engine ,,plants ,the standard voltage set--,two-cycle and four-cycle gasoline engines--,horsepower1 and fuel consumption--,efficiency of small engines and generators--,cost of operating a one-kilowatt plant4 ,electricity is of so much value in farm operations1 as well as in the farm house1 that the farmer who is not fortunate enough to possess water-power of his own1 or to live in a community where a coperative hydro-electric plant may be established1 should not deny himself its many conveniences4 ,in place of the water wheel to turn the dynamo1 there is the gasoline engine 7or other forms of internal combustion engine using oil1 gas1 or alcohol as fuel72 in many districts where steam engines are used for logging or other operations1 electricity may be generated as a by-product2 and almost any windmill capable of pumping water can be made to generate enough electricity for lighting the farm house at small expense4 ,the great advantage of water-power is that the expense of maintenance--once the plant is installed--is practically nothing4 ,this advantage is offset in some measure by the fact that other forms of power1 gas1 steam1 or windmills1 are already installed1 in many instances and that their judicious use in generating electricity does not impair their usefulness for the other farm operations for which they were originally purchased4 ,in recent years gasoline engines have come into general use on farms as a cheap dependable source of power for all operations2 and windmills date from the earliest times4 ,they may be installed and maintained cheaply1 solely for generating electricity1 if desired4 ,steam engines1 however1 require so much care and expert attention that their use for farm electric plants is not to be advised1 except under conditions where a small portion of their power can be used to make electricity as a by-product4 ,there are two types of gasoline engine electric plants suitable for the farm1 in general use3 ,first3 ,the ,standard ,voltage ,set1 in which the engine and dynamo are mounted on one base1 and the engine is kept running when current is required for any purpose4 ,these sets are usually of the #aaj-volt type1 and all standard appliances1 such as irons1 toasters1 motors1 etc41 may be used in connection with them4 ,since the electricity is drawn directly from the dynamo itself1 without a storage battery1 it is necessary that these engines be efficient and governed as to speed within a five per cent variation from no load to full load4 ,second3 ,storage ,battery ,sets1 in which the dynamo is run only a few hours each week1 and the electricity thus generated is stored by chemical means1 in storage batteries1 for use when required4 ,since1 in this case1 the current is drawn from the battery1 instead of the dynamo1 when used for lighting or other purposes1 it is not necessary that a special type of engine be used to insure constant speed4 ,the ,standard ,voltage ,set ,in response to a general demand1 the first type 7the direct-connected standard voltage set7 has been developed to a high state of efficiency recently1 and is to be had in a great variety of sizes 7ranging from one-quarter kilowatt to #be kilowatts and over7 from many manufacturers4 ,the principle of the gasoline engine as motive power is so familiar to the average farmer that it needs but a brief description here4 ,gasoline or other fuel 7oil1 gas1 or alcohol7 is transformed into vapor1 mixed with air in correct proportions1 and drawn into the engine cylinder and there exploded by means of a properly-timed electric spark4 ,internal combustion engines are of two general types--four-cycle and two-cycle4 ,the former is by far the more common4 ,in a four-cycle engine the piston must travel twice up and down in each cylinder1 to deliver one power stroke4 ,this results in one power impulse in each cylinder every two revolutions of the crank shaft4 ,on its first down stroke1 the piston sucks in gas4 ,on its first up stroke1 it compresses the gas4 ,at the height of this stroke1 the gas is exploded by means of the electric spark and the piston is driven down1 on its power stroke4 ,the fourth stroke is called the scavening stroke1 and expels the burned gas4 ,this completes the cycle4 ,a one-cylinder engine of the ordinary four-cycle type has one power stroke for every two revolutions of the fly wheel4 ,a two-cylinder engine has one power stroke for one revolution of the fly wheel2 and a four-cylinder engine has two power strokes to each revolution4 ,the greater the number of cylinders1 the more even the flow of power4 ,in automobiles six cylinders are common1 and in the last year or two1 eight-cylinder engines began appearing on the market in large numbers4 ,a twelve-cylinder engine is the prospect for the immediate future4 ,since the dynamo that is to supply electric current direct to lamps requires a steady flow of power1 the single-cylinder gas or gasoline engine of the four-cycle type is not satisfactory as a rule4 ,the lights will flicker with every other revolution of the fly wheel4 ,this would be of no importance if the current was being used to charge a storage battery--and right here lies the reason why a cheaper engine may be used in connection with a storage battery than when the dynamo supplies the current direct for lighting4 ,a two-cylinder engine is more even in its flow of power and a four-cylinder engine still better4 ,for this reason1 standard voltage generating sets without battery are usually of two or four cylinders when of the four-cycle type4 ,when a single-cylinder engine is used1 it should be of the two-cycle type4 ,in the two-cycle engine1 there is one power stroke to each up-and-down journey of the piston4 ,this effect is produced by having inlet and exhaust ports in the crank case1 so arranged that1 when the piston arrives at the bottom of the power stroke1 the waste gases are pushed out1 and fresh gas drawn in before the up stroke begins4 ,for direct lighting1 the engine must be governed so as not to vary more than five per cent in speed between no load and full load4 ,there are many makes on the market which advertise a speed variation of three per cent under normal loads4 ,governors are usually of the centrifugal ball type1 integral with the fly wheel1 regulating the amount of gas and air supplied to the cylinders in accordance with the speed4 ,thus1 if such an engine began to slow down because of increase in load1 the centrifugal balls would come closer together1 and open the throttle1 thus supplying more gas and air and increasing the speed4 ,if the speed became excessive1 due to sudden shutting off of lights1 the centrifugal balls would fly farther apart1 and the throttle would close until the speed was again adjusted to the load4 ,these direct-connected standard voltage sets are as a rule fitted with the #aaj-volt1 direct current1 compound type of dynamo1 the duplicate in every respect of the machine described in previous chapters for water-power plants4 ,they are practically automatic in operation and will run for hours without attention1 except as to oil and gasoline supply4 ,they may be installed in the woodshed or cellar without annoyance due to noise or vibration4 ,it is necessary to start them1 of course1 when light or power is desired1 and to stop them when no current is being drawn4 ,there have appeared several makes on the market in which starting and stopping are automatic4 ,storage batteries are used in connection with these latter plants for starting the engine4 ,when a light is turned on1 or current is drawn for any purpose1 an automatic switch turns the dynamo into a motor1 and it starts the engine by means of the current stored in the battery4 ,instantly the engine has come up to speed1 the motor becomes a dynamo again and begins to deliver current4 ,when the last light is turned off1 the engine stops automatically4 ,since the installation of a direct-connected standard voltage plant of this type is similar in every respect1 except as to motive power1 to the hydro-electric plant1 its cost1 with this single exception1 is the same4 ,the same lamps1 wire1 and devices are used4 ,with gasoline power1 the cost of the engine offsets the cost of the water wheel4 ,the engine is more expensive than the ordinary gasoline engine2 but even this item of cost is offset by the cost of labor and materials used in installing a water wheel4 ,the expense of maintenance is limited to gasoline and oil4 ,depreciation enters in both cases2 and though it may be more rapid with a gasoline engine than a water wheel1 that item will not be considered here4 ,the cost of lubricating oil is inconsiderable4 ,it will require1 when operated at from one-half load to full load1 approximately one pint of gasoline to each horsepower hour4 ,when operated at less than half-load1 its efficiency lowers4 ,thus1 for a quarter-load1 an average engine of this type may require three pints of gasoline for each horsepower hour4 ,for this reason it is well1 in installing such a plant1 to have it of such size that it will be operating on at least three-fourths load under normal draft of current4 ,norman ,h4 ,schneider1 in his book ,low ,voltage ,electric ,lighting1 gives the following table of proportions between the engine and dynamo3 ,actual watts ,actual ,horsepower ,nearest engine size #aej 4#e #a_/b #bbe 4#g #c_/d #cjj 4#hf #a #dej #a4ab #a-a_/d #fjj #a4e #a-a_/b #gej #a4g #a-c_/d #ajjj #b4c #b-a_/b #bjjj #d4e #e #djjj #i4j #aj ,this table is figured for an efficiency of only #dj per cent for the smaller generators1 and #fj per cent for the larger4 ,in machines from #e to #be kilowatts1 the efficiency will run considerably higher4 ,to determine the expense of operating a one-kilowatt gasoline generator set of this type1 as to gasoline consumption1 we can assume at full load that the gasoline engine is delivering #b-a_/b horsepower1 and consuming1 let us say1 #a-a_/d pint of gasoline for each horsepower hour 7to make allowance for lower efficiency in small engines74 ,that would be #c4abe pints of gasoline per hour4 ,allowing a ten per cent loss of current in wiring1 we have #ijj watts of electricity to use1 for this expenditure of gasoline4 ,this would light #ijj #be #cf lamps of #be watts each1 a liberal allowance for house and barn1 and permitting the use of small cooking devices and other conveniences when part of the lights were not in use4 ,with gasoline selling at #ab cents a gallon1 the use of this plant for an hour at full capacity would cost #j4jdg4 ,your city cousin pays #i cents for the same current on a basis of #aj cents per kilowatt-hour2 and in smaller towns where the rate is #ae cents1 he would pay #ac-a_/b cents4 ,running this plant at only half-load--that is1 using only #ah lights1 or their equivalent--would reduce the price to about #c cents an hour--since the efficiency decreases with smaller load4 ,it is customary to figure an average of #c-a_/b hours a day throughout the year1 for all lights4 ,on this basis the cost of gasoline for this one-kilowatt plant would be #af-a_/b cents a day for full load1 and approximately #aj-a_/b cents a day for half-load4 ,this is extremely favorable1 as compared with the cost of electric current in our cities and towns1 at the commercial rate1 especially when one considers that light and power are to be had at any place or at any time on the farm simply by starting the engine4 ,a smaller plant1 operating at less cost for fuel1 would furnish ample light for most farms2 but it is well to remember in this connection plants smaller than one kilowatt are practical for light only1 since electric irons1 toasters1 etc41 draw from #djj to #ffj watts each4 ,obviously a plant of #cjj watts capacity would not permit the use of these instruments1 although it would furnish #aj or #ab lamps of #be watts each4 ,,chapter ,,xi ,,the ,,storage ,,battery ,what a storage battery does--,the lead battery and the ,edison battery--,economy of tungsten lamps for storage batteries--,the low-voltage battery for electric light--,how to figure the capacity of a battery--,table of light requirements for a farm house--,watt-hours and lamp-hours--,the cost of storage battery current--,how to charge a storage battery--,care of storage batteries4 ,for the man who has a small supply of water to run a water wheel a few hours at a time1 or who wishes to store electricity while he is doing routine jobs with a gasoline engine or other source of power1 the storage battery solves the problem4 ,the storage battery may be likened to a tank of water which is drawn on when water is needed1 and which must be re-filled when empty4 ,a storage battery1 or accumulator is a device in which a chemical action is set up when an electric current is passed through it4 ,this is called charging4 ,when such a battery is charged1 it has the property of giving off an electric current by means of a reversed chemical action when a circuit is provided1 through a lamp or other connection4 ,this reversed action is called discharging4 ,such a battery will discharge nearly as much current as is required originally to bring about the first chemical action4 ,there are two common types of storage battery--the lead accumulator1 made up of lead plates 7alternately positive and negative72 and the two-metal accumulator1 of which the ,edison battery is a representative1 made up of alternate plates of iron and nickel4 ,in the lead accumulator1 the positive plate may be recognized by its brown color when charging1 while the negative plate is usually light gray1 or leaden in color4 ,the action of the charging current is to form oxides of lead in the plates2 the action of the discharging current is to reduce the oxides to metallic lead again4 ,this process can be repeated over and over again during the life of the battery4 ,because of the cost of the batteries themselves1 it is possible 7from the viewpoint of the farmer and the size of his pocketbook7 to store only a relatively small amount of electric current4 ,for this reason1 the storage battery was little used for private plants1 where expense is a considerable item1 up to a few years ago4 ,carbon lamps require from #c-a_/b to #d watts for each candlepower of light they give out2 and a lead battery capable of storing enough electricity to supply the average farm house with light by means of carbon lamps for three or four days at a time without recharging1 proved too costly for private use4 ,the ,tungsten ,lamp ,with the advent of the new tungsten lamp1 however1 reducing the current requirements for light by two-thirds1 the storage battery immediately came into its own1 and is now of general use4 ,since incandescent lamps were first invented scientists have been trying to find some metal of high fusion to use in place of the carbon filament of the ordinary lamp4 ,the higher the fusing point of this filament of wire1 the more economical would be the light4 ,edison sought1 thirty years ago1 for just the qualities now found in tungsten metal4 ,tungsten metal was first used for incandescent lamps in the form of a paste1 squirted into the shape of a thread4 ,this proved too fragile4 ,later investigators devised means of drawing tungsten into wire2 and it is tungsten wire that is now used so generally in lighting4 ,a tungsten lamp has an average efficiency of #a-a_/d watts per candlepower1 compared with #c-a_/b to #d watts of the old-style carbon lamp4 ,in larger sizes the efficiency is as low as 4#i watt per candlepower2 and only recently it has been found that if inert nitrogen gas is used in the glass bulb1 instead of using a high vacuum as is the general practice1 the efficiency of the lamp becomes still higher1 approaching 4#e watt for each candlepower in large lamps4 ,this new nitrogen lamp is not yet being manufactured in small domestic sizes1 though it will undoubtedly be put on the market in those sizes in the near future4 ,illustration3 ,the ,fairbanks ,morse oil engine storage battery set ,the tungsten lamp1 requiring only one-third as much electric current as the carbon lamp1 for the same amount of light1 reduces the size 7and the cost7 of the storage battery in the same degree1 thus bringing the storage battery within the means of the farmer4 ,some idea of the power that may be put into a small storage battery is to be had from the fact that a storage battery of only #f volts pressure1 such as is used in self-starters on automobiles1 will turn a motor and crank a heavy six-cylinder engine2 or it will run the automobile1 without gasoline1 for a mile or more with its own accumulated store of electric current4 ,the ,low ,voltage ,battery ,the #cj-volt storage battery has become standard for small lighting plants1 since the introduction of the tungsten lamp4 ,although the voltage of each separate cell of this battery registers #b4e volts when fully charged1 it falls to approximately #b volts per cell immediately discharging begins4 ,for this reason1 it is customary to figure the working pressure of each cell at #b volts4 ,this means that a #cj-volt battery should consist of at least #ae cells4 ,since1 however1 the voltage falls below #b for each cell1 as discharging proceeds1 it is usual to include one additional cell for regulating purposes4 ,thus1 the ordinary #cj-volt storage battery consists of #af cells1 the last cell in the line remaining idle until the lamps begin to dim1 when it is switched in by means of a simple arrangement of connections4 ,this maintains a uniform pressure of #cj volts from the beginning to the end of the charge1 at the lamp socket4 ,we saw in earlier chapters that the #aaj-volt current is the most satisfactory1 under all conditions1 where the current is to be used for heating and small power1 as well as light4 ,but a storage battery of #aaj volts would require at least #ee cells1 which would make it too expensive for ordinary farm use4 ,as a #cj-volt current is just as satisfactory for electric light1 this type has become established1 in connection with the battery1 and it is used for electric lighting only1 as a general rule4 ,batteries are rated first1 as to voltage2 second1 as to their capacity in ampere hours--that is1 the number of amperes that may be drawn from them in a given number of hours4 ,thus1 a battery rated at #fj ampere hours would give #fj amperes1 at #cj volts pressure1 for one hour2 #cj amperes for #b hours2 #ae amperes for #d hours2 #g-a_/b amperes for #h hours2 #c-c_/d amperes for #af hours2 etc41 etc4 ,in practice1 a battery should not be discharged faster than its #h-;hour rate4 ,thus1 a #fj-;ampere hour battery should not be drawn on at a greater rate than #g-a_/b amperes per hour4 ,this #h-;hour rate also determines the rate at which a battery should be re-charged1 once it is exhausted4 ,thus1 this battery should be charged at the rate of #g-a_/b amperes for #h hours1 with another hour added to make up for losses that are bound to occur4 ,a battery of #abj-;ampere hour capacity should be charged for #h or #i hours at the rate of #abj #h1 or #ae amperes1 etc4 ,to determine the size of battery necessary for any particular instance1 it is necessary first to decide on the number of lamps required1 and their capacity4 ,thirty-volt lamps are to be had in the market in sizes of #aj1 #ae and #bj watts2 they yield respectively #h1 #ab1 and #af candlepower each4 ,of these the #bj-watt lamp is the most satisfactory for the living rooms2 lamps of #aj or #ae watts may be used for the halls1 the bathroom and the bedrooms4 ,at #cj volts pressure these lamps would require a current of the following density in amperes3 ,candle ,power #cj-volt lamp ,amperes #h #aj watts #j4cc #ab #ae watts #j4ej #af #bj watts #j4fg ,let us assume1 as an example1 that ,farmer ,brown will use #bj-watt lamps in his kitchen1 dining room1 and sitting room2 and #aj-watt lamps in the halls1 bathroom1 and bedrooms4 ,his requirements may be figured either in lamp hours or in watt-hours4 ,since he is using two sizes of lamps1 it will be simpler to figure his requirements in watt-hours4 ,thus3 ,number ,size of ,hours ,watt- ,room of lamps lamps burned hours ,kitchen #a #bj #d #hj ,dining room #b #bj #b #hj ,sitting room #c #bj #d #bdj 7#c7 ,bedrooms #a 7each7 #aj #a #cj ,bathroom #a #aj #b #bj 7#b7 ,halls #a 7each7 #aj #d #hj ,pantry #a #aj #a #aj ,cellar #a #aj #a #aj ---- ,total #eej ,since amperes equal watts divided by volts1 the number of ampere hours required in this case each night would be #eej #cj #ah4c ampere hours2 or approximately #d-a_/b amperes per hour for #d hours4 ,say it is convenient to charge this battery every fourth day4 ,this would require a battery of #d #ah4c ampere hours1 or #gc4b ampere hours4 ,the nearest size on the market is the #hj-;ampere hour battery1 which would be the one to use for this installation4 ,to charge this battery would require a dynamo capable of delivering #aj amperes of current for #i hours4 ,the generator should be of #de volts pressure 7allowing #b-a_/b volts in the generator for each #b volts of battery7 and the capacity of the generator would therefore be #dej watts4 ,this would require a #a-a_/d horsepower gasoline engine4 ,at #a-a_/d pints of gasoline for each horsepower1 nine hours work of this engine would consume #ad pints of gasoline--or say #af pints1 or two gallons4 ,at #ab cents a gallon for gasoline1 lighting your house with this battery would cost #bd cents for four days1 or #f cents a day4 ,your city cousin1 using commercial current1 would pay #e-a_/b cents a day for the same amount of current at #aj cents a kilowatt-hour2 or #h-a_/d cents at a #ae-;cent rate4 ,if the battery is charged by the farm gasoline engine at the same time it is doing its other work1 the cost would be still less1 as the extra gasoline required would be small4 ,this figure does not take into account depreciation of battery and engine4 ,the average farmer is too apt to overlook this factor in figuring the cost of machinery of all kinds1 and for that reason is unprepared when the time comes to replace worn-out machinery4 ,the dynamo and switchboard should last a lifetime with ordinary care1 so there is no depreciation charge against them4 ,the storage battery1 a #cj-volt1 #hj-;ampere hour installation1 should not cost in excess of #ajj2 and1 if it is necessary to buy a gasoline engine1 a #a-a_/d horsepower engine can be had for #ej or less according to the type4 ,storage batteries of the lead type are sold under a two-years' guarantee--which does not mean that their life is limited to that length of time4 ,with good care they may last as long as #aj years2 with poor care it may be necessary to throw them away at the end of a year4 ,the engine should be serviceable for at least #aj years1 with ordinary replacements2 and the storage battery may last from #f to #aj years1 with occasional renewal of parts4 ,if it were necessary to duplicate both at the end of ten years1 this would make a carrying charge of #a4be a month for depreciation1 which must be added to the cost of light4 ,figuring by ,lamp ,hours ,if all the lamps are to be of the same size--either ten1 fifteen1 or twenty watts1 the light requirements of a farm house can be figured readily by lamp hours4 ,in that event1 the foregoing table would read as follows3 ,lamp hours ,kitchen1 #a lamp1 #d hours #d ,sitting room1 #c lamps1 #d hours each #ab ,dining room1 #b lamps1 #b hours each #d ,bedrooms1 #c lamps1 #a hour each #c ,halls1 #b lamps1 #d hours each #h ,bathroom1 #a lamp1 #b hours #b ,pantry and cellar1 #b lamps1 #a hour each #b ,to determine the ampere hours from this table1 multiply the total number of lamp hours by the current in amperes required for each lamp4 ,as #aj1 #ae1 and #bj-watt tungsten lamps require 4#cc1 4#ej and 4#fg amperes1 respectively at #cj volts pressure1 the above requirements in ampere hours would be #ab1 #ag-a_/b1 or #bd ampere hours1 according to the size of lamp chosen4 ,this gives the average current consumption for one night4 ,if it is desired to charge the battery twice a week on the average1 multiply the number of lamp hours by #d1 to get the size of battery required4 ,the foregoing illustration is not intended to indicate average light requirements for farms1 but is given merely to show how a farmer may figure his own requirements4 ,in some instances1 it will be necessary to install a battery of #abj or more ampere hours1 whereas a battery of #dj or #fj ampere hours would be quite serviceable in other instances4 ,it all depends on how much light you wish to use and are willing to pay for1 because with a storage battery the cost of electric light is directly in proportion to the number of lights used4 ,as a general rule1 a larger generator and engine are required for a larger battery--although it is possible to charge a large battery with a small generator and engine by taking more time for the operation4 ,how to ,charge a ,storage ,battery ,direct current only can be used for charging storage batteries4 ,in the rare instance of alternating current only being available1 it must be converted into direct current by any one of the many mechanical1 chemical1 or electrical devices on the market--that is1 the alternating current must be straightened out1 to flow always in one direction4 ,a shunt-wound dynamo must be used2 else1 when the voltage of the battery rises too high1 it may back up and turn the dynamo as a motor1 causing considerable damage4 ,if a compound dynamo is already installed1 or if it is desired to use such a machine for charging storage batteries1 it can be done simply by disconnecting the series windings on the field coils1 thus turning the machine into a shunt dynamo4 ,the voltage of the dynamo should be approximately #ej per cent above the working pressure of the battery4 ,for this reason #de-volt machines are usually used for #cj or #cb-volt batteries4 ,higher voltages may be used1 if convenient4 ,thus a #aaj-volt dynamo may be used to charge a single #b-volt cell if necessary1 although it is not advisable4 ,direction of ,current ,electricity flows from the positive to the negative terminal4 ,a charging current must be so connected that the negative wire of the dynamo is always connected to the negative terminal of the battery1 and the positive wire to the positive terminal4 ,as the polarity is always marked on the battery1 there is little danger of making a mistake in this particular4 ,when the storage battery is charged1 and one begins to use its accumulation of energy1 the current comes out in the opposite direction from which it entered in charging4 ,in this respect1 a storage battery is like a clock spring1 which is wound up in one direction1 and unwinds itself in the other4 ,with all storage battery outfits1 an ammeter 7or current measure7 is supplied with zero at the center4 ,when the battery is being charged1 the indicating needle points in one direction in proportion to the strength of the current flowing in2 and when the battery is being discharged1 the needle points in the opposite direction1 in proportion to the strength of the current flowing out4 ,sometimes one is at loss1 in setting about to connect a battery and generator1 to know which is the positive and which the negative wire of the generator4 ,a very simple test is as follows3 ,start the generator and bring it up to speed4 ,connect some form of resistance in series with the mains4 ,a lamp in an ordinary lamp socket will do very well for this resistance4 ,dip the two ends of the wire 7one coming from the generator1 the other through the lamp7 into a cup of water1 in which a pinch of salt is dissolved4 ,bring them almost together and hold them there4 ,almost instantly1 one wire will begin to turn bright1 and give off bubbles4 ,the wire which turns bright and gives off bubbles is the negative wire4 ,the other is the positive4 ,illustration3 ,a rough-and-ready farm electric plant1 supplying two farms with light1 heat and power2 and a ,ward ,leonard-type circuit-breaker for charging storage batteries ,care of ,battery ,since specific directions are furnished with all storage batteries1 it is not necessary to go into the details of their care here4 ,storage battery plants are usually shipped with all connections made1 or plainly indicated4 ,all that is necessary is to fill the batteries with the acid solution1 according to directions1 and start the engine4 ,if the engine is fitted with a governor1 and the switchboard is of the automatic type1 all the care necessary in charging is to start the engine4 ,in fact1 many makes utilize the dynamo as a self-starter for the engine1 so that all that is necessary to start charging is to throw a switch which starts the engine4 ,when the battery is fully charged1 the engine is stopped automatically4 ,the electrolyte or solution in which the plates of the lead battery are immersed1 is sulphuric acid1 diluted with water in the proportion of one part of acid to five of water1 by volume4 ,the specific gravity of ordinary commercial sulphuric acid is #a4hce4 ,since its strength is apt to vary1 however1 it is best to mix the electrolyte with the aid of the hydrometer furnished with the battery4 ,the hydrometer is a sealed glass tube1 with a graduated scale somewhat resembling a thermometer4 ,the height at which it floats in any given solution depends on the density of the solution4 ,it should indicate approximately #a4ae for a storage battery electrolyte before charging4 ,it should not be over #a4ae--or #a1aej if your hydrometer reads in thousandths4 ,only pure water should be used4 ,distilled water is the best1 but fresh clean rain water is permissible4 ,never under any circumstances use hydrant water1 as it contains impurities which will injure the battery1 probably put it out of commission before its first charge4 ,pour the acid into the water4 ,never under any circumstances pour the water into the acid1 else an explosion may occur from the heat developed4 ,mix the electrolyte in a stone crock1 or glass container1 stirring with a glass rod1 and testing from time to time with a hydrometer4 ,let it stand until cool and then pour it into the battery jars1 filling them to #a_/b inch above the top of the plates4 ,then begin charging4 ,the first charge will probably take a longer time than subsequent charges4 ,if the installation is of the automatic type1 all that is necessary is to start the engine4 ,if it is not of the automatic type1 proceed as follows3 ,first be sure all connections are right4 ,then start the engine and bring the dynamo up to its rated speed4 ,adjust the voltage to the pressure specified4 ,then throw the switch connecting generator to battery4 ,watch the ammeter4 ,it should register in amperes1 one-eighth of the ampere-hour capacity of the battery1 as already explained4 ,if it registers too high1 reduce the voltage of the generator slightly1 by means of the field rheostat connected to the generator4 ,this will also reduce the amperes flowing4 ,if too low1 raise the voltage until the amperes register correctly4 ,continue the charging operation until the cells begin to give off gas freely2 or until the specific gravity of the electrolyte1 measured by the hydrometer1 stands at #a4bd4 ,your battery is now fully charged4 ,throw the switch over to the service line1 and your accumulator is ready to furnish light if you turn on your lamps4 ,occasionally add distilled water to the cells1 to make up for evaporation4 ,it is seldom necessary to add acid1 as this does not evaporate4 ,if the battery is kept fully charged1 it will not freeze even when the thermometer is well below zero4 ,a storage battery should be installed as near the house as possible--in the house1 if possible4 ,since its current capacity is small1 transmission losses must be reduced to a minimum4 ,in wiring the house for storage battery service1 the same rules apply as with standard voltage4 ,not more than #f amperes should be used on any single branch circuit4 ,with low voltage batteries 7from #ab volts to #cb volts7 it is well to use ,no4 #aj or ,no4 #ab ,b4 ,s4 gauge rubber-covered wire1 instead of the usual ,no4 #ad used with standard voltage4 ,the extra expense will be only a few cents for each circuit1 and precious volts will be saved in distribution of the current4 ,,chapter ,,xii ,,battery ,,charging ,,devices ,the automatic plant most desirable--,how an automobile lighting and starting system works--,how the same results can be achieved in house lighting1 by means of automatic devices--,plants without automatic regulation--,care necessary--,the use of heating devices on storage battery current--,portable batteries--,an electricity route--,automobile power for lighting a few lamps4 ,the water-power electric plants described in preceding chapters are practically automatic in operation4 ,this is very desirable1 as such plants require the minimum of care4 ,it is possible to attain this same end with a storage battery plant4 ,automatic maintenance approaches a high degree of perfection in the electric starting and lighting device on a modern automobile4 ,in this case1 a small dynamo geared to the main shaft is running whenever the engine is running4 ,it is always ready to pump electricity into the storage battery when needed4 ,an electric magnet1 wound in a peculiar manner1 automatically cuts off the charging current from the dynamo1 when the battery is full2 and the same magnet1 or regulator1 permits the current to flow into the battery when needed4 ,the principle is the same as in the familiar plumbing trap1 which constantly maintains a given level of water in a tank1 no matter how much water may be drawn from the tank4 ,the result1 in the case of the automobile battery1 is that the battery is always kept fully charged2 for no sooner does the level of electricity begin to drop 7when used for starting or lighting7 than the generator begins to charge4 ,this is very desirable in more ways than one4 ,in the first place1 the energy of the battery is always the same2 and in the second place1 the mere fact that the battery is always kept fully charged gives it a long life4 ,the same result can be achieved in storage battery plants for house lighting1 where the source of power is a gasoline or other engine engaged normally in other work4 ,then your electric current becomes merely a by-product of some other operation4 ,take a typical instance where such a plant would be feasible3 ,farmer ,brown has a five horsepower gasoline engine--an ordinary farm engine for which he paid probably #ge or #ajj4 ,electric light furnished direct from such an engine would be intolerable because of its constant flickering4 ,this five horsepower engine is installed in the milk room of the dairy1 and is belted to a countershaft4 ,this countershaft is belted to the vacuum pump for the milking machine1 and to the separator1 and to a water pump1 any one of which may be thrown into service by means of a tight-and-loose pulley4 ,this countershaft is also belted to a small dynamo1 which runs whenever the engine is running4 ,the milking machine1 the separator1 and the water pump require that the gasoline engine be run on the average three hours each day4 ,the dynamo is connected by wires to the house storage battery through a properly designed switchboard4 ,the brains of this switchboard is a little automatic device 7called a regulator or a circuit breaker71 which opens and shuts according to the amount of current stored in the battery and the strength of the current from the generator4 ,when the battery is full1 this regulator is open and permits no current to flow4 ,then the dynamo is running idle1 and the amount of power it absorbs from the gasoline engine is negligible4 ,when the level of electricity in the battery falls1 due to drawing current for light1 the regulator is shut1 that is1 the dynamo and battery are connected1 and current flows into the battery4 ,these automatic instruments go still farther in their brainy work4 ,they do not permit the dynamo to charge the battery when the voltage falls below a fixed point1 due to the engine slowing down2 neither do they permit the dynamo current to flow when the voltage gets too high due to sudden speeding up of the engine4 ,necessarily1 an instrument which will take care of a battery in this way1 is intricate in construction4 ,that is not an argument against it however4 ,a watch is intricate1 but so long as we continue to wind it at stated intervals1 it keeps time4 ,so with this storage battery plant3 so long as ,farmer ,brown starts his engine to do his farm chores every day1 his by-product of electricity is stored automatically4 ,such installations are not expensive4 ,a storage battery capable of lighting #h tungsten lamps1 of #af candlepower each1 continuously for #h hours 7or fewer lamps for a longer time72 a switchboard containing all the required regulating instruments2 and a dynamo of suitable size1 can be had for from #bej to #cjj4 ,all that is necessary to put such a plant in operation1 is to belt the dynamo to the gasoline engine so that it will run at proper speed2 and to connect the wires from dynamo to switchboard1 and thence to the house service4 ,the dynamo required for the above plant delivers #aj amperes at #de volts pressure1 or #aj #de #dej watts4 ,a gasoline1 gas1 or oil engine1 or a windmill of #a-a_/b horsepower furnishes all the power needed4 ,if the farmer uses his engine daily1 or every other day1 for other purposes1 the cost of power will be practically negligible4 ,with this system electric lights are available at any time day or night2 and when the gasoline engine is in service daily for routine farm chores1 the battery will never run low4 ,this system is especially desirable where one uses a windmill for power4 ,the speed of the windmill is constantly fluctuating1 so much so in fact that it could not be used for electric light without a storage battery4 ,but when equipped with a regulator on the switchboard which permits the current to flow only when the battery needs it1 and then only when the speed of the windmill is correct1 the problem of turning wind power into electric light is solved4 99 99 99 99 99 ,if the farmer does not desire to go to the additional expense of automatic regulation1 there are cheaper plants1 requiring attention for charging4 ,these plants are identical with those described above1 except they have no regulators4 ,with these plants1 when the battery runs low 7as is indicated by dimming of the lights7 it is necessary to start the engine1 bring it up to speed1 adjust the dynamo voltage to the proper pressure1 and throw a switch to charge the battery4 ,for such plants it is customary to run the engine to charge the battery twice a week4 ,it is necessary to run the engine from #h to #aj hours to fully charge the discharged battery4 ,when the battery approaches full charge1 the fact is evidenced by so-called gassing or giving off of bubbles4 ,another way to determine if the battery is fully charged is by means of the voltmeter1 as the volts slowly rise to the proper point during the process of charging4 ,a third way1 and probably the most reliable is by the use of the hydrometer4 ,the voltage of each cell when fully charged should be #b4e2 it should never be discharged below #a4ge volts4 ,many storage battery electric light plants on the market are provided with a simple and inexpensive circuit breaker1 which automatically cuts off the current and stops the engine when the battery is charged4 ,the current is then thrown from the dynamo to the house service by an automatic switch4 ,if such a circuit breaker is not included1 it is necessary to throw the switch by hand when charging is begun or ended4 ,since the principal item of first cost1 as well as depreciation1 in a storage battery electric light plant is the storage battery itself1 the smallest battery commensurate with needs is selected4 ,since the amount of current stored by these batteries is relatively small1 electric irons and heating devices such as may be used freely on a direct-connected plant without a battery1 are rather expensive luxuries4 ,for instance1 an electric iron drawing #djj watts an hour while in use1 requires as much energy as #bj tungsten lamps of #af candlepower each burning for the same length of time4 ,its rate of current consumption would be over #ac amperes1 at #cj volts2 which would require a larger battery than needed for light in the average farm home4 ,the use to which electricity from a storage battery is put1 however1 is wholly a matter of expense involved2 and if one is willing to pay for these rather expensive luxuries1 there is no reason why he should not have them4 ,heating1 in any form1 by electricity1 requires a large amount of current proportionally4 ,as a matter of fact1 there is less heat to be had in thermal units from a horsepower-hour of electricity than from three ounces of coal4 ,when one is generating current from water-power1 or even direct from gasoline or oil1 this is not an argument against electric heating devices4 ,but it becomes a very serious consideration when one is installing a storage battery as the source of current1 because of the high initial cost1 and depreciation of such a battery4 ,farmers who limit the use of their storage battery plants to lighting will get the best service4 ,portable ,batteries ,abroad it is becoming quite common for power companies to deliver storage batteries fully charged1 and call for them when discharged4 ,without a stretch of the imagination1 we can imagine an ingenious farmer possessing a water-power electric plant building up a thriving business among his less fortunate neighbors1 with an electricity route4 ,it could be made quite as paying as a milk route4 ,illustration3 ,connections for charging storage batteries on #aaj-volt mains ,many communities have water or steam power at a distance too great to transmit #aaj-volt current by wire economically2 and because of lack of expert supervision1 they do not care to risk using current at a pressure of #ejj volts or higher1 because of its danger to human life4 ,in such a case it would be quite feasible for families to wire their houses1 and carry their batteries to the generating plant two or three times a week to be charged4 ,there are a number of portable batteries on the market suitable for such service1 at voltages ranging from #f to #cb volts4 ,the best results would be obtained by having two batteries1 leaving one to be charged while the other was in use2 and if the generating station was located at the creamery or feed mill1 where the farmer calls regularly1 the trouble would be reduced to a minimum4 ,such a battery would necessarily be small1 and of the sealed type1 similar to those used in automobiles4 ,it could be used merely for reading lamps--or it could be used for general lighting1 according to the expense the farmer is willing to incur for batteries4 ,an ordinary storage battery used in automobile ignition and lighting systems is of the #f-volt1 #fj-;ampere type1 called in trade a #f-fj4 ,lamps can be had for these batteries ranging in sizes from #b candlepower to #be candlepower4 ,a lamp of #ae candlepower1 drawing #b-a_/b amperes1 is used for automobile headlights1 and1 as any one knows after an experience of meeting a headlight on a dark road1 they give a great deal of light4 ,a #f-fj battery keeps one of these lamps running for #bd hours1 or two lamps running #ab hours4 ,a minimum of wiring would be required to install such a battery for the reading lights in the sitting room1 and for a hanging light in the dining room4 ,the customary gates for charging these batteries in a large city is #aj cents2 but in a country plant it could be made less4 ,to charge such a battery on a #aaj-volt direct current1 it is necessary to install some means of limiting the amount of current1 or in other words1 the charging rate4 ,this charging rate1 for #h hours should be1 as we have seen1 one-eighth of the ampere-hour capacity of the battery4 ,thus a #f-fj battery would require a #g-a_/b ampere current4 ,connecting two such batteries in series 7that is1 the negative pole of one battery to the positive pole of the second7 would make a #ab-volt battery4 ,ten or twelve such batteries could be connected in series1 and a #aaj-volt direct current generator would charge them in #h hours at a #g-a_/b ampere rate4 ,the diagram on page #bei shows the connections for charging on a #aaj-volt circuit4 ,an ordinary #af-;candlepower carbon lamp is of #bbj ohms resistance1 and 7by ,ohm's ,law1 ,c equals ,e divided by ,r7 permits #a_/b ampere of current to flow4 ,by connecting #ae such lamps across the mains1 in parallel1 the required #g-a_/b amperes of current would be flowing from the generator through the lamps1 and back again4 ,connect the battery in series at any point on either of the two mains1 between the lamps and the generator1 being careful to connect the positive end to the positive pole of the battery1 and vice versa4 ,lamps are the cheapest form of resistance2 but in case they are not available1 any other form of resistance can be used4 ,iron wire wound in spirals can be used1 or any of the many makes of special resistance wire on the market4 ,first it is necessary to determine the amount of resistance required4 ,we have just seen that the charging rate of a #fj-;ampere hour battery is #g-a_/b amperes4 ,applying ,ohm's ,law here1 we find that ohms resistance equals volts divided by amperes1 or ,r #aaj_/g4e #ad4fg ohms4 ,with a #bbj-volt current1 the ohms resistance required in series with the storage battery of this size would be #bi4cc ohms4 ,automobile ,power for ,lighting ,there are many ingenious ways by which an automobile may be utilized to furnish electric light for the home4 ,the simplest is to run wires direct from the storage battery of the self-starting system1 to the house or barn1 in such a way that the current may be used for reading lamps in the sitting room4 ,by a judicious use of the current in this way1 the normal operation of the automobile in the daytime will keep the battery charged for use of the night lamps1 and if care is used1 such a plan should not affect the life of the battery4 ,care should be used also1 in this regard1 not to discharge the battery too low to prevent its utilizing its function of starting the car when it was desired to use the car4 ,however1 if the battery were discharged below its starting capacity1 by any peradventure1 the car could be started by the old-fashioned cranking method4 ,using an automobile lighting system for house lighting implies that the car be stored in a garage near the house or barn2 as this battery is too low in voltage to permit transmitting the current any distance4 ,one hundred feet1 with liberal sized transmission wires is probably the limit4 ,that such a system is feasible is amply proved by an occurrence recently reported in the daily papers4 ,a doctor summoned to a remote farm house found that an immediate operation was necessary to save the patient's life4 ,there was no light available1 except a small kerosene lamp which was worse than nothing4 ,the surgeon took a headlight off his car1 strung a pair of wires through a window1 and instantly had at his command a light of the necessary intensity4 ,another manner in which an automobile engine may be used for house lighting is to let it serve as the charging power of a separate storage battery4 ,the engine can be belted to the generator1 in such a case1 by means of the fly wheel4 ,or a form of friction drive can be devised1 by means of which the rear wheels 7jacked up off the floor7 may supply the necessary motive power4 ,in such a case it would be necessary to make allowance for the differential in the rear axle1 so that the power developed by the engine would be delivered to the friction drive4 ,the following pages contain advertisements of ,macmillan books by the same author or on related subjects4 ,,water ,,power ,,engineers ,,designers ,,and ,,manufacturers ,,hunt ,,superior ,,quality ,complete equipments for developing water powers including3--,water ,wheels1 ,flumes1 ,governors1 ,supply ,pipes1 ,gates1 ,hoists1 ,valves1 ,screens1 ,gears1 ,pulleys1 ,clutches1 ,bearings1 ,shafting1 etc4 ,three types of water power developing wheels1 ranged to meet every condition4 ,illustration ,div4 ,no4 #a--,turbine ,water ,wheels for large powers and large quantities of water4 ,div4 ,no4 #b--,rim ,leverage ,wheels for small powers and very limited quantities of water4 ,div4 ,no4 #c--,small ,water ,motors for minimum water supplies under high heads4 ,send for special catalogues and ,water ,power ,blanks to fill in for estimates on suitable type of ,water ,wheel for developing your water power to best advantage4 ,,rodney ,,hunt ,,machine ,,company #fj ,,mill ,,street ,,orange1 ,,massachusetts1 ,u4,s4,a4 ,,the ,,farmer ,,of ,,tomorrow ,cloth1 #abmo1 #a4ej ,a crisp1 entertaining1 and instructive discussion of the conditions which have brought about the present agricultural problem in ,america4--,countryside ,magazine4 ,the book is interestingly written and full of many vital discussions4--,annals of the ,american ,academy of ,political and ,social ,science4 ,a popular consideration of the fundamental factors affecting the business of farming4--,pacific ,rural ,press4 ,the growing1 popular question of farming analyzed from all angles1 with many helpful suggestions4--,leslie's ,weekly4 ,any person of intelligence1 alive to the present and future welfare of his country will find ',the ,farmer of ,tomorrow1' a book of absorbing character4--,times-,star4 ,,the ,,macmillan ,,company ,publishers #fd-ff ,fifth ,avenue ,new ,york ,coperation in ,agriculture ,by ,g4 ,,harold ,,powell ,cloth1 #abmo1 #a4ej ,the author has a broad outlook and never fails to suggest that the economic advantages of coperation may frequently be quite subordinate to the general social and community interests which are fostered through a common undertaking4 ,he writes with the genuine interest of a man having experience and faith in that of which he speaks4--,political ,science ,quarterly4 ,a volume which explains in a lucid way the features of the existing system and the measures taken by farmers to protect their interests4--,journal of the ,royal ,statistical ,society4 ,mr4 ,powell has not attempted to cover the entire field of agricultural coperation1 but has confined himself to its more important phases4 ,his work shows a grasp of the issues involved and a ripeness of conclusion that comes only from actual contact with the practical side of coperation4--,american ,economic ,review4 ,the book is decidedly worth while4--,farm ,life and ,agriculture4 ,,the ,,macmillan ,,company ,publishers #fd-ff ,fifth ,avenue ,new ,york ,,rural ,,science ,,series ,edited by ,l4 ,h4 ,,bailey ,each volume illustrated4 ,cloth1 #abmo4 ,a series of practical books for farmers and gardeners1 sold as a set or separately4 ,each one is the work of a competent specialist1 and is suitable for consultation alike by the amateur or professional tiller of the soil1 the scientist or the student4 ,illustrations of marked beauty are freely used1 and the books are clearly printed and well bound4 ,,on ,,selection ,,of ,,land1 ,,etc4 ,isaac ,p4 ,roberts' ,the ,farmstead #a #ej ,t4 ,f4 ,hunt's ,how to ,choose a ,farm #a #ge ,e4 ,s4 ,cheyney and ,j4 ,p4 ,wentling's ,the ,farm ,woodlot #a #ej ,glenn ,w4 ,herrick's ,insects ,injurious to the ,household #a #ge ,,on ,,tillage1 ,,etc4 ,f4 ,h4 ,king's ,the ,soil #a #ej ,isaac ,p4 ,roberts' ,the ,fertility of the ,land #a #ej ,f4 ,h4 ,king's ,irrigation and ,drainage #a #ej ,edward ,b4 ,voorhees' ,fertilizers #a #be ,edward ,b4 ,voorhees' ,forage ,crops #a #ej ,j4 ,a4 ,widtsoe's ,dry ,farming #a #ej ,l4 ,h4 ,bailey's ,principles of ,agriculture #a #be ,s4 ,m4 ,tracy's ,forage ,crops for the ,south #a #ej ,,on ,,plant ,,diseases1 ,,etc4 ,e4 ,c4 ,lodeman's ,the ,spraying of ,plants #a #be ,,on ,,garden-,,making ,l4 ,h4 ,bailey's ,garden-,making #a #ej ,l4 ,h4 ,bailey's ,vegetable-,gardening #a #ej ,l4 ,h4 ,bailey's ,forcing ,book #a #be ,l4 ,h4 ,bailey's ,plant ,breeding #b #jj ,,on ,,fruit-,,growing1 ,,etc4 ,l4 ,h4 ,bailey's ,nursery ,book #a #ej ,l4 ,h4 ,bailey's ,fruit-,growing 7,new ,edition7 #a #ge ,l4 ,h4 ,bailey's ,the ,pruning ,book #a #ej ,f4 ,w4 ,card's ,bush ,fruits #a #ej ,w4 ,paddock ,o4 ,b4 ,whipple's ,fruit-,growing in ,arid ,regions #a #ej ,j4 ,e4 ,coit's ,citrus ,fruits ,prepar ,,on ,,the ,,care ,,of ,,live-,,stock ,nelson ,s4 ,mayo's ,the ,diseases of ,animals #a #ej ,w4 ,h4 ,jordan's ,the ,feeding of ,animals #a #ej ,i4 ,p4 ,roberts' ,the ,horse #a #be ,m4 ,w4 ,harper's ,breaking and ,training of ,horses #a #ge ,george ,c4 ,watson's ,farm ,poultry4 ,new edition #a #ej ,john ,a4 ,craig's ,sheep ,farming #a #ej ,,on ,,dairy ,,work1 ,,farm ,,chemistry1 ,,etc4 ,henry ,h4 ,wing's ,milk and ,its ,products4 ,new edition #a #ej ,j4 ,g4 ,lipman's ,bacteria and ,country ,life #a #ej ,,on ,,economics ,,and ,,organization ,william ,a4 ,mc,keever's ,farm ,boys and ,girls #a #ej ,i4 ,p4 ,roberts' ,the ,farmer's ,business ,handbook #a #be ,george ,t4 ,fairchild's ,rural ,wealth and ,welfare #a #be ,h4 ,n4 ,ogden's ,rural ,hygiene #a #ej ,j4 ,green's ,law for the ,american ,farmer #a #ej ,g4 ,h4 ,powell's ,coperation in ,agriculture #a #ej ,,the ,,macmillan ,,company ,,publishers #fd-ff ,fifth ,avenue ,,new ,,york ,,rural ,,text-,,book ,,series ,edited by ,l4 ,h4 ,,bailey ,each volume illustrated4 ,cloth1 #abmo4 ,while the ,,rural ,,science ,,series is designed primarily for popular reading and for general use1 this related new series is designed for classroom work and for special use in consultation and reference4 ,the ,,rural ,,text-,,book ,,series is planned to cover eventually the entire range of public school and college texts4 ,duggar1 ,b4 ,m4 ,physiology of ,plant ,production #a #fj ,duggar1 ,john ,frederick ,southern ,field ,crops #a #ge ,gay1 ,c4 ,warren ,principles and ,practice of ,judging ,live-,stock #a #ej ,harper1 ,m4 ,w4 ,animal ,husbandry for ,schools #a #dj ,hitchcock1 ,a4 ,s4 ,grasses #a #ej ,livingston1 ,george ,field ,crop ,production #a #dj ,lyon1 ,t4 ,l4 and ,fippin1 ,e4 ,o4 ,principles of ,soil ,management #a #ge ,mann1 ,a4 ,r4 ,beginnings in ,agriculture #ge ,montgomery1 ,g4 ,f4 ,corn ,crops #a #fj ,piper1 ,charles ,v4 ,forage ,plants and ,their ,culture #a #ge ,warren1 ,g4 ,f4 ,elements of ,agriculture #a #aj ,warren1 ,g4 ,f4 ,farm ,management #a #ge ,wheeler1 ,h4 ,j4 ,manures and ,fertilizers #a #fj ,widtsoe1 ,john ,a4 ,principles of ,irrigation ,practice #a #ge ,,the ,,macmillan ,,company ,publishers #fd-ff ,fifth ,avenue ,new ,york ,the ,rural ,outlook ,set ,by ,l4 ,h4 ,,bailey ,four ,volumes4 ,each1 cloth1 #abmo4 ,uniform binding1 attractively boxed4 #e4jj per set2 carriage extra4 ,each volume also sold separately4 ,in this set are included three of ,professor ,bailey's most popular books as well as a hitherto unpublished one1--,the ,country-,life ,movement4 ,the long and persistent demand for a uniform edition of these little classics is answered with the publication of this attractive series4 ,,the ,,country ,,life ,,movement ,cloth1 #abmo1 #bbj pages1 #a4be postage extra ,this hitherto unpublished volume deals with the present movement for the redirection of rural civilization1 discussing the real country-life problem as distinguished from the city problem1 known as the back-to-the-land movement4 ,,the ,,outlook ,,to ,,nature 7,new and ,revised ,edition7 ,cloth1 #abmo1 #aie pages1 #a4be postage extra ,in this alive and bracing book1 full of suggestions and encouragement1 ,professor ,bailey argues the importance of contact with nature1 a sympathetic attitude toward which means greater efficiency1 hopefulness1 and repose4 ,,the ,,state ,,and ,,the ,,farmer 7,new ,edition7 ,cloth1 #abmo1 #a4be postage extra ,it is the relation of the farmer to the government that ,professor ,bailey here discusses in its varying aspects4 ,he deals specifically with the change in agricultural methods1 in the shifting of the geographical centers of farming in the ,united ,states1 and in the growth of agricultural institutions4 ,,the ,,nature ,,study ,,idea 7,new ,edition7 ,cloth1 #abmo1 #a4be postage extra ,it would be well1 the critic of ,the ,tribune ,farmer once wrote1 if ',the ,nature ,study ,idea' were in the hands of every person who favors nature study in the public schools1 of every one who is opposed to it1 and most important1 of every one who teaches it or thinks he does4 ,it has been ,professor ,bailey's purpose to interpret the new school movement to put the young into relation and sympathy with nature1--a purpose which he has admirably accomplished4 ,,the ,,macmillan ,,company ,,publishers #fd-ff ,fifth ,avenue ,,new ,,york 99 99 99 99 99 ,transcriber's ,notes3 ,the square root symbol is indicated by sqrt7447 ,exponents are indicated by ,bold in a table is indicated by 44