available by the ,digital ,library of the ,falvey ,memorial ,library1 ,villanova ,university 7https3_/_/digital4library4villanova4edu 7 file which includes the original illustrations4 ,see #eghid-;h4htm or #eghid-;h4zip3 7https3_/_/www4gutenberg4org_/cache_/epu b_/#eghid_/pg#eghid-;images4html7 or 7https3_/_/www4gutenberg4org_/files_/#eg hid_/eghid-;h4zip7 ,images of the original pages are available through the ,digital ,library of the ,falvey ,memorial ,library1 ,villanova ,university4 ,see https3_/_/digital4library4villanova4edu_ /,item_/vudl3#ejdjij ,transcriber's ,note3 ,text enclosed by underscores is in italics 7italics74 ,text enclosed by equal signs is in bold face 7bold74 ,an additional ,transcriber's ,note is at the end4 ,illustration3 ,how ,to ,do ,,mechanical ,,tricks ,,how ,,to ,,do ,,mechanical ,,tricks4 ,containing ,complete ,instruction for ,performing ,over ,sixty ,ingenious ,mechanical ,tricks4 by ,a4 ,,anderson4 ,fully ,illustrated4 ,new ,york3 ,frank ,tousey1 ,publisher1 #bd ,union ,square4 ,entered according to ,act of ,congress1 in the year #aijb1 by ,frank ,tousey1 in the ,office of the ,librarian of ,congress at ,washington1 ,d4 ,c4 99 99 99 99 99 ,,contents ,the ,pile of ,draughtsmen4 ,the ,decanter1 ,card1 and ,coin4 ,a ,clever ,blow4 ,the ,obedient ,coin4 ,to ,cut a ,string ,with ,your ,hands4 ,the ,rebound4 ,a ,fiery ,catapult4 ,to ,make an ,exact ,balance4 ,the ,recomposition of ,light4 ,the ,mysterious ,apple4 ,economical ,letter-,scales4 ,tracing a ,spiral4 ,the ,inclined ,plane4 ,to ,cut a ,bottle ,with a ,string4 ,equilibrium of a ,knife in ,mid-,air4 ,a ,trick ,with ,four ,matches4 ,the ,distance of an ,inaccessible ,point4 ,practical ,tracing of a ,meridian ,line4 ,to ,measure the ,height of a ,mountain4 ,to ,take ,up ,four ,knives with ,one4 ,the ,tack in the ,ceiling4 ,the ,jumping ,pea4 ,to ,acquire a ,true ,eye4 ,the ,air-,tight ,stopper4 ,the ,fusee ,rocket4 ,a ,novel ,table ,mat4 ,geometrical ,paper ,band4 ,photographic ,camera4 ,the ,phantom ,needle4 ,amphitrite4 ,optical ,illusions4 ,the ,insensible ,coin4 ,the ,asses' ,bridge4 ,another ,way to ,prove the ,preceding ,theorem4 ,indented ,angles4 ,a ,cheap ,shooting ,gallery4 ,the ,coin in ,equilibrium4 ,the ,submerged ,coin4 ,the ,smoke ,rings4 ,the ,walking ,cork4 ,the ,obstinate ,cork4 ,petroleum ,pulverizer4 ,electric ,attraction and ,repulsion4 ,the ,bust of the ,sage4 ,the ,witchery of the ,hand4 ,the ,perspectograph4 ,camphor in ,water4 ,a ,simple ,multiplier4 ,the ,drawing ,room ,mirror4 ,elementary ,gas-,burner4 ,rapid ,vegetation4 ,miniature ,volcanoes4 ,,how ,,to ,,do ,,mechanical ,,tricks4 ,the ,pile of ,draughtsmen4 8,matter is inert40 ,that is what you read in every treatise on physics--what does it mean8 ,here is a very simple experiment that will prove this truth to anyone4 ,pile up ten draughtsmen1 as shown in ,fig4 #a4 ,before this pile place another piece on edge1 and pressing its circumference with the forefinger1 let it glide from underneath so that it strikes the pile with considerable force4 ,the piece so thrown must1 you will think1 upset the whole pile of draughts2 but no3 the piece thus sharply sent forward will strike only one piece of the pile1 and this alone will be dislodged without putting the others out of their equilibrium1 and the whole column above will settle down together on the bottom piece4 ,illustration3 ,fig4 #a4 ,in effect1 the force of the impulse1 making itself felt on the piece that is touched1 the latter leaves the pile without transmitting its movement to the other pieces1 which1 following another physical law1 that of gravity1 descend vertically to fill the place left vacant4 ,the experiment may be varied by using a knife and striking with it a sharp horizontal blow on one of the pieces4 ,the piece struck will fall out of the pile without disturbing the symmetry of the others4 ,the ,decanter1 ,card1 and ,coin4 ,this law of 8,inertia0 will provide us with a few more experiments as curious as they are conclusive4 ,place a playing or an ordinary visiting card on a decanter2 upon the card and just in the center1 over the aperture of the decanter1 put a small coin 7a dime74 ,now1 if with a sharp fillip1 given horizontally on the edge of the card1 you succeed in whisking it off 7which is very easy71 the coin will fall to the bottom of the decanter4 ,the following phenomenon has taken place3 the movement was too rapid to be transmitted to the coin1 and the card alone was whisked off4 ,illustration ,the coin being no longer sustained by the card falls1 of course1 vertically1 without having in the least come out of position4 ,a sharp horizontal knock given with a penholder or small stick on the edge of the card1 will produce the same result1 but the fillip is more effective4 ,a ,clever ,blow4 ,take a thin stick about a yard long1 and thrust a pin firmly in each of its extremities4 ,this done1 place the stick on the bowls of two pipes1 which a couple of persons hold by the stems1 in such a manner that the pins only rest on the pipes4 ,a third person then strikes the stick sharply in the middle1 and it will break without injuring the pipes4 ,ordinary clay pipes will do very well1 as the more brittle the pipes are1 the more striking is the experiment4 ,how is this explained8 ,illustration ,the mechanical effect of the shock has not time to reach the bowls of the pipes 7inertia71 and is only manifested at the very point on which the blow falls1 hence the stick unable to resist the force of the blow at the one point breaks in two pieces4 ,the ,obedient ,coin4 ,take an ordinary wooden matchbox1 and remove the drawer holding the matches4 ,in the center place a small coin1 a cent will be the best for the experiment1 the object of which is to make the coin fall into the interior without touching it4 ,tap lightly on that side of the box to which you desire the coin to come1 until it rests upon the edge4 ,illustration ,then slightly raise the end of the box whereon the coin rests1 and lightly tap with the finger once more4 ,at once the coin will fall into the box4 ,the secret of the experiment is this3 the taps on the box only move the box1 while the coin retains its position by reason of its own inertia1 until the edge of the box reaches it4 ,the last tap knocks away the support1 and the coin1 obedient to the law of gravity1 falls vertically into the interior of the box4 ,this little experiment is easily performed1 and extremely interesting when done neatly4 ,to ,cut a ,string ,with ,your ,hands4 ,with a little practice1 and some briskness of movement1 you may be able to break a string of considerable thickness by proceeding as follows3 ,wind the string round your left hand1 so as to make a loop1 as shown in the figure4 ,pass it three or four times round the fingers to insure the solidity of the loop4 ,seize firmly the other end of the string with your right hand1 around which you wind it three or four times1 then give a brisk pull4 ,the string will be clean cut at the junction of the loop in the left hand4 ,illustration ,when the knack is well acquired1 one may break the string on two fingers only1 by following always the same theory as above4 ,the ,rebound4 ,on the neck of a bottle place a cork in an upright position4 ,the cork must be large enough to rest on the neck without falling in4 ,now give a sharp fillip on the neck of the bottle1 and you will see the cork fall1 not on the other side of the bottle as most people expect1 but forward in the direction of the hand giving the blow4 ,this1 again1 is an illustration of the principle of inertia4 ,a rapid blow tends to push the bottle from the cork before the movement is transmitted to the latter4 ,few people will execute this experiment properly the first time1 for the instinctive fear to break the bottle and cut their fingers1 will prevent them giving a blow sharp enough to make this experiment successfully at the first attempt2 but with a little perseverance1 the necessary degree of force will be gauged to a nicety4 ,illustration ,a ,fiery ,catapult4 ,take a match-box and place it upright edge-wise and place two matches in each side between the inner and outer box1 heads up4 ,they must be inserted deeply enough to stick firmly4 ,place a third match cross-wise between them and it will stay there by the pressure the latter exercises on them4 ,now light the middle of the horizontal match and wait4 ,what do you think will happen8 ,ask the bystanders which will first catch fire8 ,the natural conclusion they will draw will be the following4 ,from the middle the frame will spread of course to the two extremities and light the other two matches1 probably this side first where the two phosphorous heads meet4 ,illustration ,well1 nothing of the sort happens4 ,when the volume of the burning match has diminished1 and consequently its rigidity also1 the force of its resistance grows weaker as the combustion proceeds4 ,a moment comes when the two vertical matches1 trying to assume again their original position1 throw off1 with a sway1 the burning horizontal match4 ,the burning match was rendered flexible in the middle1 and is not at all burned at the ends1 and the two matches remain standing as before4 ,to ,make an ,exact ,balance4 ,to construct by yourselves1 with the help of simple materials a balance of great precision may seem impossible4 ,nevertheless it can be done4 ,a ruler1 a tin box1 7in which blacking was contained1 for example7 three blocks of wood1 two pins1 thread1 four nails1 a small piece of glass1 and cardboard are all the necessary materials1 and now to work4 ,at a short distance from the center of the ruler1 and on a cross line with one another1 stick two pins so that they come out a little on the other side4 ,at one end of the ruler1 in ,c1 nail a small piece of your box4 ,illustration ,at the spot1 where the hook to which the scale is suspended1 is to hang1 make an indentation with the point of a nail1 so that the hook does not shift at the other extremity1 in ,a1 fasten a flat piece of tin1 which will form one of the scales of your balance4 ,at the end of this pan solder a pin point downwards4 ,your second scale1 ,b1 destined to contain the object or substances to be weighed1 will be formed by the lid of the blacking-tin4 ,on its rim at nearly equal distances pierce four holes1 on which the suspension-strings will be tied1 the latter at their upper end being united together in one string1 which is tied to a hook 7a bent pin or fishing hook will do47 ,now the point of support remains to be constructed4 ,on a wooden square1 rather thick1 ,e1 fix another block1 ,g1 on which gum a piece of glass4 ,in the largest block knock four nails to prevent the shaft of the balance swerving from right to left4 ,the small truncated pyramid1 ,d1 which you perceive on the left of the design1 and which is graduated1 serves as bench-mark4 ,in order to weigh you use the method due to ,borda1 called the method of double weights4 ,place in the scale ,a a weight which you think is slightly over the one of the substance or object to be weighed4 ,then the scale ,b being occupied1 get equilibrium by shifting more or less towards the ruler1 the weight on the scale ,a4 ,then note the division indicated by the pin point1 and take from scale ,b the article placed there1 and put therein weights until the point of scale ,a tells you that the equilibrium is the same as when the substance was in the scale4 ,it is not necessary that this balance be exact1 provided it answers the very small differences in the pans4 ,the one we have indicated will weigh down to a fifty-thousandth part of a pound4 ,the ,recomposition of ,light4 ,it is a great pity that exquisitely beautiful facts and mysteries are wrapped up in the crack-jaw terms of foreign languages1 and so made to appear ugly4 ,there is no branch of knowledge more fascinating than light4 ,to follow up its study is like walking along a shady lane1 where at certain distances apart the wayfarer lights upon jewels of great brilliance4 ,it has been said above that white light is formed by the union or combination of seven colors4 ,when a ray of light passes through a prism it is split up into the parts of which it is composed1 and seven colors as in the rainbow appear4 ,these colors shade off into one another with every variety of tint1 like a band of rainbow-colored ribbon4 ,this band is called a spectrum4 ,now1 where science classes are held there may be seen a complicated instrument1 which is used to show how the seven colors unite to form white light4 ,it is a disc on which the colors of the spectrum are painted1 and it is made to spin round with great rapidity4 ,the impression received by the eye1 when looking at the revolving disc is total abstinence of color4 ,in other words it is white light4 ,fortunately1 you can satisfy yourselves on this point without any other materials than a cardboard disc and a piece of string4 ,on this disc paint in small sections the colors of the spectrum1 repeating them four or five times in the following order3 red1 orange1 yellow1 green1 blue1 indigo1 violet4 ,illustration ,that the experiment may be entirely successful1 the sections must be marked off according to the following scale of width of section4 ,let orange1 next to the circumference represent #b3 then ,red will be represented by #e ,orange 8 8 8 #b ,yellow 8 8 8 #e ,green 8 8 8 #d ,blue 8 8 8 #e ,indigo 8 8 8 #c ,violet 8 8 8 #e ,now1 in any diameter of the disc bore two holes not too near the edge4 ,through them pass a piece of string1 and knot the two ends together4 ,take hold of the string with both hands1 and make the disc spin round4 ,then extend and approach the hands alternately to give a very rapid movement to the disc4 ,when revolving rapidly enough you will not be able to distinguish the separate colors4 ,they all become blended into white light4 ,the ,mysterious ,apple4 ,pierce an apple in such a manner as to obtain two holes tending toward the middle1 and forming a pretty large angle as shown in the figure4 ,two quills or tin tubes should be inserted to make the inside passages smooth4 ,pass a string through the hole and your apple is prepared for a little trick1 which1 you may be sure will astonish all persons before whom you practice it1 and who of course are not yet initiated4 ,you fasten one extremity of the string to your foot1 and take the other in your hand so as to produce at will the rigidity of the string4 ,you can then command the apple to go down1 or to stop1 and it will obey your order immediately4 ,indeed1 when you straighten the string1 the part which enters the apple pushes against the angle formed by the two passages1 and by the pressure1 holds the apple4 ,when on the contrary you let go a little1 you take away the rigidity and the apple glides down4 ,illustration ,you can therefore alternately let the apple go down or stop its course1 and we repeat it1 persons not in the secret cannot imagine by what means you get this curious result4 ,if1 instead of an apple one takes a wooden ball1 the experiment will be more interesting and the article will last longer4 ,economical ,letter-,scales4 ,take a watch or small clock spring1 and fix it by the center on a stick4 ,at the other end attach a small brass hook to hold letters1 etc41 as shown in the figure4 ,at the top of the hook fix horizontally a small band1 running over a strip of cardboard1 likewise hanging on the stick4 ,now graduate the cardboard strip with real weights1 or their exact equivalents1 and after this any small articles may be weighed with sufficient accuracy4 ,the spring1 being of steel1 always turns to its original position when the scale is empty4 ,illustration ,tracing a ,spiral4 ,in geometry the process for tracing a spiral by the help of compasses is pretty long and tedious4 ,the following method will enable you to do it far more quickly and as accurately4 ,illustration ,take a wooden or cardboard cylinder1 with a diameter equal to a fourth part of the distance you require between the spires 7or trelices7 to be traced4 ,on this cylinder fasten one end of a string1 ,b1 and wind it up1 and attach to the other end a pencil1 ,c1 or a point1 according to what you want to do4 ,now you have only to turn to right or left according to the direction in which the string was wound up1 by holding the pencil down and keeping the string tight1 and a spiral of perfect regularity will be traced4 ,the above figure clearly shows the process4 ,the cylinder ,a has a diameter equal to the distance ,r ,s divided by #d4 ,the ,inclined ,plane4 ,take a piece of paper1 roll it up into a tube large enough to hold a marble1 and gum it lengthwise4 ,then introduce a marble and close the extremities with a strip of paper as shown below4 ,illustration ,when you think that it is well dried you place it upright on the upper end of an inclined board1 or flat ruler1 leaning on a pile of books for example4 ,you will then see the paper cylinder lie down1 get up and so on till it reaches the bottom of its course4 ,the effect is very curious and will be more so if you are somewhat of an artist1 and able to draw or paint a figure on the cylinder4 ,to ,cut a ,bottle ,with a ,string4 ,gum first two circular pads of paper on each side of the spot where you intend to cut your bottle4 ,these pads are obtained by gumming several strips of paper one over the other1 so as to leave between them a groove on which you wind the string round once4 ,catch hold of the extremities of the string1 and draw it to and fro1 see-saw fashion1 by which friction the part of the glass operated on will be heated4 ,illustration ,as soon as you think that the glass is hot enough1 plunge the bottle in cold water1 which you will have placed handy before1 and at the spot where the friction was exercised the glass will be clean cut4 ,according to the thickness of the glass1 more or less heat must be produced4 ,this process is infallible4 ,the same result can also be produced in another way4 ,it is1 when once the heat is sufficient to let glide a few drops of water along the string4 ,the string must be well wetted4 ,the cut will be as clean as by the other process4 ,equilibrium of a ,knife in ,mid-,air4 ,be reassured dear readers1 we are not going to ask you to make a balance in mid air1 that would be too much for our weak capabilities4 ,the question is simply to swing a knife horizontally in the space which surrounds us4 ,the experiment is curious and easily executed4 ,illustration ,take the cork of a champagne bottle4 ,pierce it lengthwise with a sharp knife1 and let the knife stick out a third of its length from the thin end of the cork4 ,then insert into each side of the cork the prongs of two forks1 so that they are perpendicular with the blade of the knife as shown in figure4 ,this operation accomplished1 you have only to suspend the point of the blade on the loop of a string1 and the knife will hang horizontally4 ,you may then swing it if you choose1 and the movement will not destroy the equilibrium4 ,a ,trick ,with ,four ,matches4 ,speaking of matches1 there is yet one more trick to be played with four of them4 ,at the non-phosphoric ends of two matches cut a small notch so that they fit into each other4 ,stretch the matches apart so as to form an angle1 and place them vertically upon the table4 ,then lean a third match against them so as to form a tripod1 standing by itself4 ,the question now is to take up this trivet with a fourth match and carry it to another place without disturbing the harmony of the little construction4 ,illustration ,at first sight this seems impossible2 it is1 however1 easily done4 ,you have only to slide the fourth match between the two stuck together1 and the one serving as support4 ,by lightly pressing against the two first ones the third one will slide1 and its upper extremity will come between the angle formed by the two others4 ,by taking it up briskly1 this extremity will be maintained1 and you are then enabled to carry the little tripod to another place4 ,the ,distance of an ,inaccessible ,point4 ,everyone knows what an angle is1 and you say at once it is the inclination of two lines that meet each other4 ,these lines by their branching off form an opening more or less wide4 ,this opening is measured by the aid of an instrument called a protractor made of brass or horn1 which finds its place in nearly every box of mathematical instruments4 ,it represents a semi-circumference1 divided into #ahj equal parts1 called degrees1 written thus3 #ahj4 ,each degree is divided into #fj minutes1 expressed thus3 #fj min42 and finally the minutes are divided again in #fj parts1 called seconds1 indicated thus3 #fj sec4 ,there are therefore in a whole circumference1 #cfj deg41 #b1afj min41 and #ab1ifj sec4 ,one degree1 therefore1 is the #cfjth part of a circumference1 and thus we have a measure independent of all dimensions4 ,for example1 on a round table of #cf yards in circumference1 one degree will be marked by one tenth of a yard2 on a pond of #cfj yards in circumference1 one degree will be equal to one yard4 ,the degree1 therefore1 may be more or less1 but it is always the #cfjth part of the circumference of a circle4 ,let it be quite understood that1 whether an angle is to be on a sheet of paper1 or in the skies1 the divisions do not change4 ,illustration ,this must be well grasped1 it is of the utmost importance for the explanations which follow4 ,it is therefore settled3 the measure of the angles has nothing to do whatever with a measure of length4 ,we have shown how to measure an angle4 ,let us examine now what is a triangle1 without pondering too much over this geometrical figure1 which every one knows4 ,the essential property of this three-cornered figure is that the sum of its three angles is always equal to #ahj degrees4 ,in other words1 the protractor placed successively at each angle will give three numbers1 which1 added1 make up #ahj degrees4 ,keep this property well in mind1 as it will serve us hereafter4 ,now1 to what distance does a degree correspond8 ,for example1 take a yardstick1 and with the graphometer 7an instrument by which angles are measured71 in readiness1 carry it from the latter instrument to a certain distance1 till the two extremities of the yardstick measure one degree2 this yard is then said to subtend an angle of one degree4 ,now1 measure the distance which divides the yardstick from the instrument1 and you will find it to be #eg yards4 ,therefore1 one degree corresponds to an object being at a distance of #eg times its height4 ,a man two yards high at a distance of #eg times his height1 or #aad yards will measure one degree4 ,one minute will be represented by a piece of cardboard of a hundreth part of a yard long seen from a distance of #cd yards2 and finally1 a second will be given by a card a hundreth part of a yard seen from a distance of #bjfb yards4 ,a hair seen at #bj yards about represents a second4 ,this perhaps1 you think to be too small to be seen by the naked eye4 ,suppose that you to measure the distance of a church situated on a height1 and from which you are separated by a river 7see fig47 ,choose on the river's bank two spots from which the steeple ,c can be seen1 say ,a and ,b4 ,at ,b plant a surveying-staff1 and with the graphometer1 go to ,a and find the angle formed by ,b ,a ,c4 ,suppose for example1 it reads #hd degrees4 ,repeating the operation at ,b for the measure of the angle ,c ,b ,a1 suppose it to be #ie degrees4 ,measure the distance from ,a to ,b and let it be #hj yards4 ,now here is the statement of our problem3 ,how to resolve a triangle of which the base is known to be #aj yards1 and two of its angles4 ,well1 we have said above that the sum of the three angles is always the same1 equal to #ahj degrees1 having on one side #hd1 and on the other #ie1 that makes together #hd by #ie1 equal to #agi degrees4 ,the difference between this number and #ahj is #a degree1 therefore the angle ,,abc measures one degree4 ,we know that an angle of one degree corresponds to a distance of #eg yards4 ,multiply the base of our triangle by #eg yards and you obtain a distance of the church from the points ,a and ,b1 #aj by #eg1 equal to #egj yards4 ,nothing is more simple than this4 ,illustration ,the smaller the measured angle the further off the object will be4 ,as seen in our figure1 the upright lines1 m o1 m' o'1 m1 o11 do not vary1 but according to their distances from point ,c1 they form various angles1 ac1 a'c'1 a1c11 becoming smaller and smaller4 ,a graphometer is not always to be had4 ,when approximate distances only are required1 the following contrivance may be used4 ,trace on a cardboard of large size a semi-circumference which one divides first into #ahj equal parts1 then each of these is divided again in #b1 #c1 #d divisions1 etc41 according to the size given to the circumference1 which constitutes a large protractor4 ,to measure an angle place the cardboard upright in an horizontal position1 supporting it by the center of the semi-circumference by means of a screw fixed on a stick4 ,then proceed as stated above4 ,from a pin stuck in the center mark the spot where the visual ray passes1 go to ,a and to ,b1 and you get approximately the desired result4 ,practical ,tracing of a ,meridian ,line4 ,the meridian line of a place is an imaginary line passing through this place and the center of the sun1 when the latter is at the highest point of the arc of the circle1 which it daily describes4 ,at that very moment it is noonday exactly at the place in question4 ,as the position of the earth changes from day to day1 the sun does not every day touch the meridian line at noon2 sometimes it is in advance1 sometimes behind4 ,various instruments have been invented to indicate in a practical manner the meridian of a place4 ,we owe the following construction to ,mr4 ,e4 ,brunner of the longitudinal office4 ,illustration ,on a window-sill in a southerly position1 fix in a solid1 permanent manner1 a small cupful of quicksilver2 cover it with a lid made of varnished metal1 and pierced in its center by a small round hole about a quarter of an inch in diameter4 ,this lid must fit well1 but not too tightly1 so as to permit its being lowered in close proximity to the surface of the quicksilver4 ,when the window is open the solitary ray reflected on the mercury will be projected on the ceiling of the room4 ,at the exact noonday the center of the mirror and the center of the reflected image are in the meridian plane4 ,it remains only to be traced4 ,at the moment of its passage one marks in ,b1 for example1 a spot corresponding to the center of the reflected image2 one knocks a small nail there1 and with a string connect this point with another outside the window1 so that the string passes through the center of the diaphragm1 ,m4 ,the line1 ,b ,m1 is the meridian plane4 ,from ,a1 suspend a lead-line which meets the string1 ,b ,m4 ,all you have to do now is to join on the ceiling the points1 ,a ,b1 and continue them to ,d4 ,a black thread may be stretched to serve as the line1 and this is the meridian required4 ,to get the mean time one has only to note the exact passage1 and deduct the corrections given in various astronomical papers4 ,to ,measure the ,height of a ,mountain4 ,one can1 without instruments1 take the height of a building or a mountain1 provided you are able to measure their base4 ,a yardstick and two ordinary sticks are enough4 ,suppose the height of the tower1 ,e ,f1 is to be taken4 ,illustration ,some distance off plant a stick1 a yard high1 ,a ,b2 one yard from this we plant another and longer one1 ,c ,d4 ,measure exactly the distance1 ,b ,f1 and applying the eye at ,a1 we aim at the summit of the tower1 ,e2 mark on the stick1 ,c ,d1 the point where the visual ray meets the stick1 i4e41 point ,g4 ,then1 by measuring the distance1 ,d ,g1 and subtracting one yard you get ,g ,i1 and may be expressed in the following statement3 ,a ,h 3 ,a ,i 33 ,e ,h 3 ,g ,i ,in the given example let us suppose that ,a ,h #aej yards1 ,a ,i will1 of course1 be equal to one yard2 ,g ,i 1 say four fifths of a yard2 the problem will be3 #aej yards 3 #a yard 33 x 3 four fifths of a yard4 ,work the sum out1 and the value of x is #abj yards4 ,having taken our lease1 ,a ,h1 at one yard from the ground1 we must add one yard to #abj1 making #aba yards1 which is the height of the tower wanted4 ,to ,take ,up ,four ,knives with ,one4 ,here is one more trick of equilibrium1 which appears to be interesting enough to find a place among these experiments4 ,we need not give any long explanations1 for our figure fully illustrates the way in which it has to be executed4 ,illustration ,first place a knife straight before you1 then two others which you place1 blade upon blade1 over the first4 ,finally1 the two last ones are arranged transversely1 their blades passing over those of the two knives put down in the second instance1 and below the blade of the first knife4 ,by taking hold of the handle of the first knife1 you can lift them up all at once without breaking the equilibrium4 ,the ,tack in the ,ceiling4 ,to nail a tack in the ceiling without hammer1 using a ladder or chair to reach it1 seems as impossible as pulling the moon down from the sky4 ,yet1 with a little cleverness1 it is quite an easy thing to do4 ,place a tack1 head downwards1 on a half dollar1 then place a small piece of tissue paper over it1 so that the point of the tack passes through4 ,illustration ,then turn the sides of the paper down round the coin4 ,throw the whole1 point upwards1 violently against the ceiling1 trying to keep this projectile of a new description from turning over on its course4 ,with a little practice the knack is soon acquired4 ,the tack enters the ceiling1 the violence of the shock tears the paper1 which1 carried away by the coin1 falls to the ground4 ,suppose you have a light object to suspend on the ceiling2 you may do it in this manner without much trouble4 ,simply tie a thread to the tack1 the object being attached to the other end4 ,if the projectile is well thrown the tack will go right in1 and stick very firmly4 ,the ,jumping ,pea4 ,take an unbroken straw1 four or five inches long1 not closed by knots1 but forming a tube1 and about one twentieth of an inch in diameter4 ,divide one of its extremities to a length of about half an inch in four1 five or six parts1 which separate slightly1 so as to form a truncated cone4 ,after having thus prepared the straw1 take a dry pea1 with a larger diameter than that of the tube1 and place it in the cone4 ,hold the tube upwards1 and blow into it at the opposite end4 ,illustration ,the pea will be forced upward by the air column which you blow into the tube4 ,it will remain suspended in the air as long as the interior pressure continues1 then fall back into the arms of the cone4 ,to vary that experiment pass a long pin through the pea1 the point of which is turned into the tube4 ,when well thrown up1 the pea can be maintained at a distance of two or three inches from the mouth of the straw4 ,according to the stronger or weaker blast of breath1 the pea will go up or down4 ,to ,acquire a ,true ,eye4 ,here is a peculiar and clever recreation1 easily performed1 though at first sight it may appear difficult4 ,put a tumbler upside down4 ,by means of bread crumbs1 fix a match vertically on the top4 ,on the edge of the table place another match1 partly raised on a piece of cork or wood4 ,stoop down and aim at the vertical match on the glass1 so that the one on the table is in the exact line of fire4 ,when you think it is aimed straight1 give it a fillip on the lower end1 it will shoot up and touch the one placed on the glass if the aim be good4 ,illustration ,if you succeed1 you may congratulate yourself on having good eyes--a very desirable gift if you should have to handle a gun1 as a soldier or a sportsman4 ,the ,air-,tight ,stopper4 ,how many times has it happened to you1 when wanting to cork a bottle1 that the intended cork was too large to enter the neck8 ,what have you done8 ,cut the cork all round1 and obtained1 but imperfectly1 the desired end4 ,illustration ,next time when the same occasion arises1 turn the difficulty in this way3 ,instead of attacking the sides1 cut four notches1 bevel-shaped1 into the cork as shown in the figure4 ,treated in this manner your cork will fit1 and close the bottle hermetically4 ,the ,fusee ,rocket4 ,for this you only want a simple match box4 ,take out a match1 and holding it on to the box as shown in figure1 i4e41 hold the box a little slanting1 between the thumb and forefinger1 and place the match head downwards on the side of the emery paper1 where the match ignites when rubbed against4 ,with medium force press on the match and with the other hand give it a fillip in the direction indicated by the arrow4 ,the little missile will fly into the air all ablaze1 and fall down at a distance of four1 five1 or even six yards4 ,with a little practice you will succeed each time4 ,it looks like a small rocket1 especially when done in complete darkness4 ,illustration ,be careful to make the experiment only where there is no danger of setting anything on fire4 ,a ,novel ,table ,mat4 ,to construct this original table mat #f objects1 always at hand when table is laid for a meal1 are required2 #c knives and three tumblers of equal size and arrange the tumblers upside down1 in the form of a triangle1 and on each of them rest the handle of a knife4 ,cross the blades so that the first laid passes over the second and the second over the third1 this latter passing over the first ,x4 ,illustration ,the blades sustain themselves and you may place on them a dish or any other heavy object1 without being afraid of a collapse4 ,the arrangement is sufficiently shown in the design with out requiring more detailed explanation4 ,geometrical ,paper ,band4 ,take a band of paper1 say a postal wrapper2 you observe that it has two lines and two surfaces 7interior surface and exterior surface47 ,the problem is to arrange it so that it presents only one line and one surface4 ,it may seem improbable1 yet it is possible as you will see4 ,cut the band and gum together again the two pieces thus separated1 after having turned over one of them as shown in figure as above4 ,arranged in this manner the paper has but one line and one surface1 for it has the aspect of a screw without end4 ,illustration ,photographic ,camera4 ,here is a simple way to construct a camera for a pocket photographic apparatus4 ,illustration3 ,fig4 #a4 ,cut out of strong cardboard a piece of about #b to #b-a_/d inches square4 ,in the middle cut out a circle a little smaller than the lens with which you cover it1 so that this lens holds on the edge of the hole4 ,cut out also two triangles of cardboard1 having one side equal to the square1 and a length in proportion to the focus of the lens2 say for a simple lens of #c inch focus1 and one inch diameter1 a length of one and a half inches4 ,illustration3 ,fig4 #b4 ,paste the two triangles on the square at ,a and ,b1 their base ,c must hold a rectangular mirror of the same dimensions as the side ,c of the square and the side of the triangles4 ,on side ,d fix a roughened glass pane1 or instead1 a thin transparent sheet of paper2 tissue paper for example4 ,illustration3 ,fig4 #c4 ,cut a black piece of cardboard as indicated in ,fig4 #c ,c2 the dotted lines indicate the sides to be turned down4 ,this shade is fixed on to the camera4 ,illustration3 ,fig4 #d4 ,pass through the holes1 ,s ,s1 an iron rod or a long needle1 which must pass likewise through the upper angle of the triangles1 forming the sides1 7,fig4 #a74 ,when your lens has been fixed on the round hole of the square your camera is complete4 ,the shade produces complete obscurity so that the operator can see in the middle of the camera the object or person he wishes to photograph4 ,in order to fix it on the photographic apparatus1 one may fasten a wire1 in the form of an elongated ,u1 just below the mirror at ,e4 ,the ,phantom ,needle4 ,you know that when you sit at a window with a looking-glass in your hand1 you can catch a beam of sunlight on the glass and throw it into the eyes of a person on the other side of the street4 ,illustration ,what have you done in this case8 ,you answer at once that you have bent the sunlight out of its course and turned it in another direction4 ,if the glass were not there it would fall in a straight line on the window seat4 ,this bending out of the straight line is called reflection4 ,now for an experiment2 cut a small round piece of cork1 not quite half an inch thick4 ,run a needle into its center and place it in a tumbler two-thirds full of water1 needle downwards4 ,looking down on the cork you cannot see the needle4 ,now alter your position1 and stoop down so that your eye is on level with the table on which the glass stands4 ,then you will perceive the needle to be on the top of the cork4 ,this apparent topsy-turveydom is called total reflection4 ,the needle is reflected on the top of the water1 and as the ray from your eye meets the top of the water1 you see the needle1 as it were1 on the top of the cork4 ,amphitrite4 ,at fairs1 and in halls of mysteries a variety of optical illusions are presented4 ,under the name of ,amphitrite1 the spectacle is sometimes of a woman who seems to rise from the deep1 moves about in the empty space1 apparently without being sustained by anything or anybody4 ,she seems completely isolated in mid-air4 ,she turns about1 sometimes in a circle1 moving now the legs1 then the arms4 ,then after several graceful evolutions in all directions1 she stands straight and descends rapidly1 seemingly precipitated into a decorated scenery representing the ocean4 ,illustration ,the illusion is produced in this way3 ,behind a well-stretched muslin curtain1 ,m ,m1 is painted ,d ,d1 with the sky and clouds1 below a canvas representing the sea4 ,in front1 in the direction of ,g ,g1 is a mirror1 without quicksilver back1 inclined at an angle of forty-five degrees4 ,below the mirror is a round table moving on a pivot1 and on this the actress1 who takes the part of the ,amphitrite1 lays down4 ,in executing various movements1 the table in turning1 reflects in the glass the image of the person on whom a vivid light is thrown4 ,the spectators placed at ,s see the image on the canvas at the back1 ,d ,d4 ,when the time comes for making the lady disappear altogether1 the table1 which glides on rails1 is drawn off the stage1 and ,amphitrite seems to plunge into the waters4 ,it is by this process that the specters and ghosts at the theaters are produced4 ,you can perform this illusion1 based on the reflection of the light at home1 in reducing its construction to the simple proportions of a small theater of marionettes4 ,optical ,illusions4 ,illusions of the eye are numberless1 and afford a wide field for experiment4 ,for example1 if you ask any one wearing a silk high hat1 to what height he thinks his hat would reach if placed on the ground against the wall or door4 ,nine times out of ten the mark of the height guessed will be half as much again1 at least a third over the real height of the hat4 ,illustration ,again1 represents two triangles4 ,ask which is the one whose center is the better indicated4 ,every one will say1 8triangle ,a40 ,well1 every one will be wrong1 it is ,b4 ,take a pair of compasses and you will easily prove it4 ,illustration ,the same occurs with the above figure4 ,the two parallelograms1 ,a ,b1 are absolutely equal1 and yet ,a appears to be larger than ,b4 ,the two lines1 ,a and ,b are both of equal length2 yet ,b seems a third longer than ,a4 ,the sides1 ,,ab1 ,,cd1 ,,bd of the middle figure1 ,,be1 ,,am1 ,,em1 etc41 are equal1 yet it seems to the eye that the surface1 ,a ,b ,e ,m1 is longer than the square ,a ,b ,c ,d4 ,there is another deception the eye is liable to4 ,on a sheet of paper trace several circles1 having the same center4 ,place the sheet on your thumb and turn it horizontally1 it will then seem to you as if the rounds turned1 though you watch with the utmost attention1 the illusion will be complete4 ,illustration ,in order to terminate this series1 which can be varied infinitely1 we will1 in our turn1 ask you this question3 ,which is the tallest man of the three personages appearing in the adjoining figure8 ,is it the first1 the last1 or the middle one8 ,try to find out without any instrument of course1 simply by the aid of your eyes which you suppose exact and true4 ,it will appear to you at first sight that the artist has made a mistake1 and has made a bad drawing4 ,the last seems the tallest1 whereas the first seems shortened4 ,illustration ,however1 measure with a pair of compasses1 and the illusion will at once disappear4 ,the draughtsman was not mistaken2 the first is the tallest1 and the two others go diminishing in height4 99 99 99 99 99 ,this terminates our experiments on optical illusions and you will now enter upon another field of knowledge altogether4 ,the ,insensible ,coin4 ,cut a piece of cardboard about six inches long1 and by sticking the extremities together with a pin1 or with gum1 form a circle or ring4 ,balance it carefully on the neck of a wine bottle or decanter1 and on the top of the ring place a dime1 exactly over the neck of the bottle4 ,now the trick to be performed is to take off the ring so that1 without touching it1 the coin falls into the bottle4 ,on the inner side of the ring give a sharp knock with the finger1 or1 better still1 with the thumb and forefinger1 as in shooting a marble1 as shown in figure4 ,the ring will come off1 and the coin which on account of its inertia1 does not participate in the movement1 will infallibly fall into the bottle4 ,it is absolutely necessary to strike the interior of the circle1 because in striking it from the outside one would not get any result at all1 on account of the elasticity of the cardboard4 ,illustration ,the ,asses' ,bridge4 ,every schoolboy knows which is the famous geometrical theorem1 commonly called the ,asses' ,bridge1 and which is propounded as follows3 ,illustration ,the square constructed on the hypotenuse of a right angled triangle is equivalent to the sum of the squares constructed on the two other sides4 ,if we had only to propound this terrible theorem1 it would be an easy matter1 but the question is to prove it by ,a and ,b1 and by means of the triangles1 similar angles1 equivalents1 etc4 ,well1 instead of all this1 we give here a very simple way to prove the truth2 if not quite pedagogic1 it is none the less real4 ,trace on a piece of cardboard or thick paper a square1 and divide into #di parts4 ,this done1 cut it out in following the big lines4 ,take out on the center one division1 which add to the small square1 and then construct the figure #b4 ,illustration3 ,fig4 #b4 ,the right-angled triangle ,a ,c ,d will be found by the sides of the three squares1 and the sum of the two small squares constructed on the two sides of the triangle will be equivalent to the great square constructed on the hypotenuse4 ,effectively3 ,square ,no4 #a has #i divisions4 ,square ,no4 #b has #af divisions4 -- ,together #be ,and the square ,no4 #c has also #be divisions4 ,therefore the theorem is proved4 ,another ,way to ,prove the ,preceding ,theorem4 ,in a square ,a ,b ,d ,c1 trace four similar and equal triangles2 cut them out and dispose them as shown in ,fig4 #a4 ,you will have in the middle an empty space forming a great square1 which just has one of the sides of the hypotenuse of the right-angled triangle ,a ,e ,b4 ,illustration ,trace the outlines of this square and remount the triangles one against the other1 ,h ,c ,e1 against ,a ,e ,b1 and ,c ,d ,g1 against ,b ,f ,g1 you will get the ,fig4 below4 ,illustration3 ,fig4 #a4 ,the successively covered and uncovered parts of the two squares have not changed in extent4 ,but this time the uncovered part is formed of the two squares #b and #c which correspond to those constructed on the two other sides of the triangle1 ,a ,e ,b4 ,this very simple demonstration has the advantage of being applicable to any rectangle4 ,indented ,angles4 ,given two sheets of paper of the same size and form of a rectangle1 fold them both in four equal parts1 one lengthwise and the other sideways1 as shown below4 ,illustration3 ,fig4 #a4 ,when so folded take a fourth part off each4 ,part ,a in the figures4 ,the question is now to cover quite exactly one of the remaining surfaces with the other1 in cutting the latter in two perfectly equal parts4 ,illustration3 ,fig4 #b4 ,to resolve this question take the surface 7parts ,a having been detached71 with which it is intended to cover the other1 fold it again into equal parts1 but this time in the opposite way to the one in which it was folded first1 as indicated in ,fig4 #d3 cut it out then in following the dotted line1 ,f ,l1 formed by the marks of the fold2 this done one will obtain two parts absolutely equal1 ,f ,l4 ,illustration3 ,fig4 #c4 ,in order to cover the other surface1 ,fig4 #c1 all that is now necessary is to lower the angles1 viz43 angle ,a'1 must be in front of angle ,a1 angle ,b' in front of angle ,b1 and angle ,c' in front of angle ,c4 ,when the angles are lowered in this way1 the two surfaces will be quite similar1 and can be covered one by the other4 ,illustration3 ,fig4 #d4 ,this experiment can be made either with one or the other sheet1 in lowering or raising the angles4 ,in the example shown here it is the fourth ,figure which is destined to cover the other one4 ,when the operation is terminated as indicated above1 part ,m1 of ,fig4 #d1 will be at ,m' of ,fig4 #c1 and part ,o at ,o' of the covert figure4 ,a ,cheap ,shooting ,gallery4 ,with a whalebone stay busk1 make a bow and draw a target on a card4 ,for the arrows1 divide lengthwise a steel nib1 choosing long shaped ones in the form of a lance and fix each part at the end of a match4 ,you now have complete a saloon shooting gallery1 inoffensive and sufficiently recreative at least for your smaller friends4 ,illustration ,the ,coin in ,equilibrium4 ,here is a curious demonstration of the balancing of bodies having their center of gravity displaced by a counterpoise4 ,we propose to keep a coin horizontally in equilibrium on the rim of a tumbler1 and it must rest on the glass only by its extreme edge1 as shown by the figure which gives the complete demonstration4 ,illustration ,take a silver dollar and place it between the prongs of two forks covering each other1 then place the edge of the coin upon the glass and draw the handles of the forks together1 or distend them till the whole are balanced4 ,the center of gravity will then be at the point of contact1 and you may give a slight swing without the risk of breaking the equilibrium thus obtained4 ,the ,submerged ,coin4 ,in order to make the previous experiment more significant1 you may present it also in the following manner3 ,in a soup plate place a coin2 beside the latter an inverted glass1 then pour water into the plate just to cover the coin4 ,you then inform the spectators that you will withdraw the coin from the plate without wetting your fingers4 ,you will meet with a great deal of disbelief from many of your friends looking on4 ,leave them in doubt as to the success of your operation4 ,cut a round piece off a cork1 on the top of which place some pieces of paper and matches1 push the whole underneath the glass1 light the matches and wait4 ,as soon as the combustion is over1 you will see the water leave the plate and enter the glass1 wherein it rises1 leaving the piece absolutely dry at the bottom of the plate4 ,you can then execute what you offered at first--take out the coin without wetting your fingers4 ,illustration ,as a variation of the preceding experiment1 obtain a flat-bottomed tumbler or glass goblet 7but the bottom must be flat71 a pocket handkerchief and a coin4 ,these are to be seen by everybody present4 ,procure a watch glass1 or a round piece of glass like an eye-glass4 ,this is not to be shown4 ,now show to the bystanders that you place the coin 7say a fifty-cent piece1 for example7 in the middle of the handkerchief1 and1 throwing back two sides of the latter1 point out again that the coin is still in its place4 ,to show that there is no deception ask someone to hold the coin in the handkerchief4 ,then place underneath it a glass containing a little water and call out1 8,hey1 ,presto6 ,fly60 ,the person lets go of the coin and the noise of its falling to the bottom of the glass is plainly heard4 ,you take up the handkerchief1 and every one is astonished at the disappearance of the coin1 which you can produce from another person's hat4 ,really the trick is very simple4 ,for the coin supposed to be held in the handkerchief you must dexterously substitute the watch glass or eye glass4 ,the person holding it1 of course1 declares he has the coin fast4 ,when he drops the eye glass it makes the same noise against the tumbler as would the coin1 though1 of course1 it cannot be seen in the water4 ,it is a capital trick if smoothly performed4 ,the ,smoke ,rings4 ,when the air of a room is very calm1 have you ever noticed that tobacco smoke rises slowly and in a nearly vertical direction8 ,have you never watched with interest the grayish or bluish streaks of smoke issuing from the smoke of a cigar or pipe8 ,and in seeing the smoke rise in such a capricious fashion1 have you ever ascertained that it is due to the calm of the surrounding air8 ,one may get some amusement out of the agitation of the atmosphere4 ,for the materials you only require a square or round cardboard box1 in the lid of which cut a round hole of about two inches in diameter4 ,in the interior of the box place two sheets of blotting paper1 the one impregnated with muriatic acid1 the other with ammoniac1 in equal quantities4 ,immediately a whitish smoke will escape through the hole and rise straight to the ceiling4 ,if with both hands you give a series of simultaneous taps on the sides of the box1 you will see the smoke issue in well defined rings1 which will disperse rapidly in the air1 and succeed each other as long as you continue the pressure4 ,these rings are the result of the concussion of the air which you occasion in the box4 ,the experiments can be made also with ordinary tobacco smoke1 but it will last longer in the way we have indicated4 ,illustration ,the ,walking ,cork4 ,stick two knives in a cork1 on the same level1 and opposite each other1 so as to form a balance4 ,in the bottom of the cork1 at an equal distance1 insert two pins1 sufficiently deep not to bend under the weight which they will have to carry4 ,rest the pins on a flat ruler1 slightly inclined1 and give them a slight balancing movement4 ,the weight of the apparatus will fall on the pin1 ,a1 on which the whole turns the knife placed at the side1 ,b1 will knock against the support1 and will tend to bring the apparatus again into its original position as the oscillating movement continues1 pin1 ,b1 will1 in its turn1 support the whole weight1 and pin1 ,a1 will shift on to the other point1 ,a1 indicated in the figure4 ,the walking cork will thus continue its movement till it has gone over the course assigned to it4 ,this recreation is interesting1 for it demonstrates once more that all bodies are attracted by the earth1 and that1 as soon as they are thrown off their balance they obey the force which constantly draws them down4 ,illustration ,the ,obstinate ,cork4 ,take a glass or metal tube1 closed at one end1 and cut a stopper in cork or india-rubber to its size so that it closes the tube hermetically1 and take care that it glides in the tube without difficulty1 and pierce it with a hole4 ,on the top of this hole adapt a small piece of leather1 rather larger than the hole1 which you must take care to wet before proceeding with the following experiment4 ,in order to be able to withdraw the cork when in the tube1 you take the precaution to fasten in it both ends of a piece of string1 as indicated in the figure4 ,illustration ,these various objects being prepared1 will serve to demonstrate once more the atmospheric pressure4 ,lift the valve up1 force the cork into the tube towards the middle1 and when there1 put the valve in its place again1 and pull quickly on the string as if trying to pull the cork out4 ,the latter will not come out1 for the reason that producing a vacuum before itself1 the atmospheric prepare will prevent it from coming out4 ,but if instead you draw it gently towards you1 it will offer much less resistance1 because the outer air will enter through the smallest interval between the cork and the glass1 and partly destroy the exterior pressure4 ,petroleum ,pulverizer4 ,with the aid of the compressed air reservoir you are able to conduct various soldering operations1 requiring often great heat4 ,let us construct the following pulverizer3 ,into a bottle of the shape shown in the figure1 put some petroleum1 and introduce a glass tube that does not quite reach the bottom4 ,close with wax that no air can enter1 and at the upper extremity of the tube let a fitting be embedded1 a section of which is shown in the engraving4 ,this fitting has three openings1 two horizontals and one corresponding with the tube that is plugged into the petroleum4 ,illustration ,adjust the india-rubber tube to the reservoir1 and when the pressure is exercised on the surface of the liquid it will force the petroleum upwards through the tube1 and thence it will be blown in a fine spray1 which burns as if coming out of an ordinary burner4 ,the particles of oil are mixed with air1 and consequently the atoms of air are heated to a high degree4 ,this jet develops a heat of great intensity4 ,this pulverizer may serve also to disinfect rooms4 ,you have only to replace the petroleum with an antiseptic liquid4 ,electric ,attraction and ,repulsion4 ,the poles of the same sign repel1 and the contrary poles attract each other1 or1 in other words1 the negative1 or the positive electricity attracts the electricity of a contrary sign1 whereas the electricities of the same signs repel each other4 ,in order to demonstrate this principle we will contrive a little plaything which will be as interesting as amusing to see in operation4 ,illustration ,for a pivot take a needle stuck in a cork1 and1 as magnetic needles1 two old corset steels will do very well4 ,if these cannot be had a clock spring may do instead4 ,magnetize these two steel rods by rubbing them with a magnet4 ,in the middle of one of the rods punch a small hollow so that it may freely move on the needle in the cork without fear of falling off4 ,you have thus manufactured a rough compass4 ,then cut out four dolls in paper1 two gentlemen and two ladies1 and stick them in the extremities of the two magnetized needles4 ,remember to put at each end a figure of the opposite sex4 ,now1 each time you present a man to the other man1 which is placed on the magnetized needle1 they will repel each other2 if to a lady1 the dolls are attracted4 ,the explanation is easy4 ,you will have taken care to put the puppets on contrary poles3 a man on the positive pole1 a lady on the negative pole4 ,in this way the principle enunciated above is thoroughly proved and easily grasped4 ,one may easily vary this experiment by replacing the gentlemen and ladies by personages of actual notoriety1 or of the company1 in placing them in groups which have a mutual dislike to each other1 such as the schoolmaster and pupil1 etc4 ,the ,bust of the ,sage4 ,every person wonders how the sensational decapitation scene is produced4 ,to all appearance a head is thrust through the neck opening of a guillotine1 the knife descends and the head is cut off4 ,however1 in order that none of the fair sex may be alarmed1 it may be varied as follows3 ,in a cabinet a mirror is set across1 sloping from the top at the back to the front4 ,it reflects the ceiling1 which is covered with the same material as that which is seen of the floor in front of the mirror4 ,in the center of the glass is cut a hole which admits of the passing through of a man's head4 ,he sits or stands in under the glass at his ease4 ,the front edge of the mirror is concealed by a few astronomical and geographical instruments1 old folio books1 skulls1 etc4 ,the head and shoulders are made up and draped like one of the seven wise men of ,greece1 and he answers questions in a grave1 portentous voice4 ,the ,witchery of the ,hand4 ,in order to ascertain the existence of animal magnetism the following apparatus1 very simple1 and not at all difficult to construct1 answers perfectly4 ,stick a pin in a cork1 point upwards4 ,on that pivot place horizontally a sheet of paper so that it remains in perfect equilibrium4 ,illustration ,if you now put your hand over the sheet of paper1 a rotary movement will manifest itself1 the sheet swerving from right to left4 ,this movement is caused by the influence of the hand's magnetism4 ,the ,perspectograph4 ,this simple instrument1 invented by ,mr4 ,jarlot1 renders the tracing of a sketch extremely easy1 besides avoiding absolutely faults of perspective1 which is1 without doubt1 the principal advantage of this instrument4 ,thanks to it1 one obtains an easy reproduction on one plane of objects placed on different planes4 ,here is a description of this very simple instrument4 ,a wooden frame ,a ,b ,c ,d1 with a slot in the side1 ,a ,b1 in which a pane of glass can slide so as to cover the whole space of the frame1 a1 b1 c1 d1 is fixed on a stand4 ,illustration ,the frame is maintained in a perfectly horizontal position by means of a water level n n'1 placed on the lower side of the frame4 ,at ,e is a small rule moving on a hinge at ,e1 allowing the angle to be varied at the plane ,a ,b ,c ,d1 by resting it on two supports ,e ,e'4 ,the supports themselves move round on an axle fixed on the rule4 ,at the extremity ,e' of this rule is fixed a copper blade curved in ,e'1 ,c'1 and pierced by a small hole of about an eighth of an inch in circumference1 the edges are made thinner as represented in the diagram placed above2 the widened part is turned toward the frame4 ,so much for the body of the instrument1 now for the accessories4 ,in the slot left in side1 ,a ,b ,c ,d1 lower a glass pane covering the space1 a1 b1 c1 d1 which is not1 however1 a necessary condition1 it depends on the size of the design you desire to take4 ,this pane requires a little preparation4 ,it is done in this way3 ,one chooses a pane of the desired glass1 as free as possible from defects4 ,cover one side only with turpentine1 and which you know is a natural varnish4 ,see that this coating is as thin as possible1 and to ensure this1 go over the surface with a very soft brush steeped in the liquid4 ,when you see that the latter does not run any more1 leave off brushing4 ,let it dry for two days if necessary2 take care1 meanwhile1 to protect the varnished side from dust4 ,now it remains only to show the use of the instrument4 ,put yourself in front of the object you wish to represent4 ,put the frame in a perfectly horizontal position1 slide the pane in it1 and dispose the rule1 ,e ,e' 7,fig4 #b71 in such a manner that1 when looking through the little hole1 ,o1 you are able to see the object you want to draw4 ,illustration3 ,fig4 #b4 ,then1 with a blue or other colored pencil1 trace the outlines of the object on the glass coated with turpentine1 the use of the latter being to allow the pencil marks to fix itself on the surface4 ,one sees that the outlines thus obtained will be those of the real object as clearly as possible because they are traced as seen1 so to speak4 ,but the principal object of the instrument is not so much exactness of outline as to get the exact proportion existing between the different sizes of the objects placed in different planes4 ,we will try to show this last result by means of another figure4 ,suppose ,a ,b to be an object situated at a certain distance from the eye posted at o1 the rays from the eye1 ,o ,a ,o ,b1 meets the instrument at a and b1 and the image of this object is given by the line1 a b4 ,now1 suppose ,a' ,b' to be another object situated beyond ,a ,b2 the eye has not changed position1 it cannot do so1 with reference to the glass1 on account of the small rule which is fixed2 the image of the object ,a' ,b'1 will be a' b'2 thus1 one has the true dimensions of ,a' ,b'1 in respect to ,a ,b4 ,it is precisely this proportion which must exist between the sizes of the objects placed in different planes1 which constitute perspective4 ,the instrument1 therefore1 well deserves its name of ,perspectograph4 ,it will be observed that this apparatus obviates two difficulties3 #a1 that of the exactness of the sketch1 in copying nature as it is presented to the eye2 #b1 that of perspective4 ,having the sketch on glass it is easy to transfer it on paper4 ,lift up the rule1 ,e ,e'1 so as not to be in the way1 place oiled or transparent paper on the glass1 and counter-draw the sketch on it4 ,you can then stick this paper on a cardboard1 and1 if the operator is a designer1 he may reproduce in crayon a very fine drawing4 ,for the shading he must use his own talent1 the aim of the instrument not being to give a finished drawing1 but only a sketch1 vigorously exact1 and in unexceptionable perspective4 ,this instrument is often very convenient4 ,when wishing to have a true sketch1 you trace it on the glass2 you then transfer it to an oil-paper1 and again on drawing paper if the former is not to be used4 ,besides1 if one has an exact sketch on whatever paper1 you may reproduce it in freehand1 if you are blessed with any idea of drawing4 ,if the varnished plane has to serve again1 wash it with warm water1 and let it get dry2 then the varnishing can be done over again4 ,camphor in ,water4 ,if you put very small pieces of camphor on the water1 you will see them turn round each other with great velocity4 ,these movements are due to the diminution of the superficial tension of the liquid in the vicinity of the pieces of camphor4 ,in order to stop them throw a drop of oil in the water1 and you will produce a perfect calm4 ,one may utilize the camphor for an amusing recreation4 ,construct a small paper or cardboard boat and fasten underneath on the hind part or stern a piece of camphor4 ,your boat will maneuver on the water4 ,persons not initiated will be much puzzled1 and be long to find out by what contrivance this small craft is propelled4 ,a ,simple ,multiplier4 ,write on a card or strong paper the letters1 figures1 etc41 which you want to reproduce4 ,then all along the lines or tracing1 with a needle1 prick holes in close proximity at equal distances4 ,place the sheet so prepared on a pad made of several sheets of blotting paper1 smeared with blue analine ink1 or a mixture of lamp-black and oil4 ,fix the corners with tacks or drawing pins1 and draw your copies by simply placing the blank sheets over the pricked one1 and press them down4 ,the words1 figures or designs will be reproduced in dotted lines if the holes have been well pricked4 ,in this way a good number of copies can be drawn4 ,the ,drawing ,room ,mirror4 ,on one of the faces of a pane of glass smear some lamp-black mixed with oil4 ,if you place this glass1 thus prepared1 vertically on an engraving representing flowers1 fruits1 birds1 etc41 you will obtain an infinity of forms1 some of which will be very striking4 ,illustration ,if you want to reproduce these1 to fix their outlines1 you have only to interpose a transparent paper1 to draw along the glass pane a line in pencil and to trace over the part of the picture which terminates at the foot of the pane4 ,fold the transparent paper along this pencil line1 and to get the whole reproduced you have only to copy over the designs just traced4 ,the glass1 which does the duty of a mirror1 doubles the forms in a symmetrical way1 and as it is moved new forms come to view4 ,elementary ,gas-,burner4 ,fill an old round tin box1 at least two inches high1 with sawdust and pieces of blotting paper4 ,close it as well as possible1 and introduce a small metal1 or glass1 tube in the lid to a depth of about one-third of the box4 ,make the joint tight with putty4 ,put this box on any two supports and place the flame of a lamp or candle underneath it4 ,illustration ,soon the overheated sawdust and blotting paper will evolve vapors of alcohol and combustible gases4 ,approach a lighted match to the upper end of the tube and you will see the gas ignite and continue to burn4 ,rapid ,vegetation4 ,a cheap sponge can be converted into a hanging bunch of greenery for room decoration4 ,plunge it into hot water1 press it dry1 then put in its holes or pores seeds of millet1 red clover1 barley1 linseed1 grasses1 etc41 in fact any species of plants which germinate easily and produce1 as far as possible1 leaves or blades of different shades4 ,place the sponge thus prepared on a vase or in a saucer1 or better still1 suspend it in the recess of a window1 where it may get as much sunshine as possible4 ,every morning1 for a week1 sprinkle its surface lightly with water4 ,soon the seeds will germinate and grow4 ,in a short time they will form a ball of greenery1 making a charming decoration for a room4 ,illustration ,miniature ,volcanoes4 ,in a rather large porcelain or glazed earthenware basin place a small quantity of nitrate of lead4 ,this may be obtained for a few cents from any painters' supplies store4 ,then upon it throw some flakes of sal ammoniac4 ,immediately a number of conical elevations will be formed1 which give off vapors and burst with a popping noise4 ,illustration ,altogether the experiment represents very exactly1 volcanoes in a state of eruption4 ,when the eruption ceases1 the rough1 broken state of the remaining mats1 represents as nearly as a thing on this earth of ours can1 the appearance of the moon through a powerful telescope4 ,indeed the moon at one time of its history was undoubtedly in the soft lava-like state that you will observe in the basin1 during the first stage of this elegant and instructive experiment4 ,illustration3 ,,the ,,end4 99 99 99 99 99 ,,useful ,,and ,,instructive ,,books4 ,,how ,,to ,,do ,,the ,,black ,,art--,containing a complete description of the mysteries of ,magic and ,sleight-of-,hand1 together with many wonderful experiments4 ,by ,a4 ,anderson4 ,illustrated4 ,price #aj cents4 ,address ,frank ,tousey1 publisher1 ,n4 ,y4 ,,how ,,to ,,be ,a ,,detective--,by ,old ,king ,brady1 the world known detective4 ,in which he lays down some valuable and sensible rules for beginners1 and also relates some adventures and experiences of well-known detectives4 ,price #aj cents4 ,for sale by all newsdealers in the ,united ,states and ,canada1 or sent to your address1 post-paid1 on receipt of price4 ,address ,frank ,tousey1 publisher1 ,new ,york4 ,,how ,,to ,,become ,a ,,conjurer--,containing tricks with ,dominoes1 ,dice1 ,cups and ,balls1 ,hats1 etc4 ,embracing #cf illustrations4 ,by ,a4 ,anderson4 ,price #aj cents4 ,address ,frank ,tousey1 publisher1 ,new ,york4 ,,how ,,to ,,do ,,mechanical ,,tricks--,containing complete instructions for performing over sixty ,mechanical ,tricks4 ,by ,a4 ,anderson4 ,fully illustrated4 ,price #aj cents4 ,for sale by all newsdealers1 or we will send it by mail1 postage free1 upon receipt of price4 ,address ,frank ,tousey1 ,publisher1 ,n4 ,y4 ,,how ,,to ,,do ,,sixty ,,tricks ,,with ,,cards--,embracing all of the latest and most deceptive card tricks with illustrations4 ,by ,a4 ,anderson4 ,price #aj cents4 ,for sale by all newsdealers1 or we will send it to you by mail1 postage free1 upon receipt of price4 ,address ,frank ,tousey1 ,publisher1 ,n4 ,y4 ,,how ,,to ,,make ,,electrical ,,machines--,containing full directions for making electrical machines1 induction coils1 dynamos1 and many novel toys to be worked by electricity4 ,by ,r4 ,a4 ,r4 ,bennett4 ,fully illustrated4 ,price #aj cents4 ,for sale by all newsdealers in the ,united ,states and ,canada1 or will be sent to your address1 post-paid1 on receipt of price4 ,address ,frank ,tousey1 publisher1 ,new ,york4 ,,how ,,to ,,become ,a ,,bowler--,a complete manual of bowling4 ,containing full instructions for playing all the standard ,american and ,german games1 together with rules and systems of sporting in use by the principal bowling clubs in the ,united ,states4 ,by ,bartholomew ,batterson4 ,price #aj cents4 ,for sale by all newsdealers in the ,united ,states and ,canada1 or sent to your address1 postage free1 on receipt of the price4 ,address ,frank ,tousey1 publisher1 ,new ,york4 ,,how ,,to ,,keep ,,and ,,manage ,,pets--,giving complete information as to the manner and method of raising1 keeping1 taming1 breeding1 and managing all kinds of pets2 also giving full instructions for making cages1 etc4 ,fully explained by #bh illustrations1 making it the most complete book of the kind ever published4 ,price #aj cents4 ,address ,frank ,tousey1 publisher1 ,new ,york4 ,,how ,,to ,,do ,,electrical ,,tricks--,containing a large collection of instructive and highly amusing electrical tricks1 together with illustrations4 ,by ,a4 ,anderson4 ,price #aj cents4 ,for sale by all newsdealers1 or sent1 post-paid1 upon receipt of the price4 ,address ,frank ,tousey1 publisher1 ,new ,york4 ,,how ,,to ,,write ,,letters--,a wonderful little book1 telling you how to write to your sweetheart1 your father1 mother1 sister1 brother1 employer2 and1 in fact1 everybody and anybody you wish to write to4 ,every young man and every young lady in the land should have this book4 ,it is for sale by all newsdealers4 ,price #aj cents1 or sent from this office on receipt of price4 ,address ,frank ,tousey1 publisher1 ,new ,york4 ,,how ,,to ,,do ,,puzzles--,containing over #cjj interesting puzzles and conundrums with key to same4 ,a complete book4 ,fully illustrated4 ,by ,a4 ,anderson4 ,price #aj cents4 ,for sale by all newsdealers1 or sent1 post-paid1 upon receipt of the price4 ,address ,frank ,tousey1 ,publisher1 ,new ,york4 ,,how ,,to ,,do #dj ,,tricks ,,with ,,cards--,containing deceptive ,card ,tricks as performed by leading conjurers and magicians4 ,arranged for home amusement4 ,fully illustrated4 ,price #aj cents4 ,address ,frank ,tousey1 publisher1 ,new ,york4 ,,how ,,to ,,make ,a ,,magic ,,lantern--,containing a description of the lantern1 together with its history and invention4 ,also full directions for its use and for painting slides4 ,handsomely illustrated1 by ,john ,allen4 ,price #aj cents4 ,for sale by all newsdealers in the ,united ,states and ,canada1 or will be sent to your address1 post-paid1 on receipt of price4 ,address ,frank ,tousey1 publisher1 ,new ,york4 ,,how ,,to ,,become ,,an ,,actor--,containing complete instructions how to make up for various characters on the stage2 together with the duties of the ,stage ,manager1 ,prompter1 ,scenic ,artist and ,property ,man4 ,by a prominent ,stage ,manager4 ,price #aj cents4 ,address ,frank ,tousey1 publisher1 ,n4 ,y4 99 99 99 99 99 ,,our ,,ten ,,cent ,,hand ,,books4 ,,useful1 ,,instructive ,,and ,,amusing4 ,containing valuable information on almost every subject1 such as ,writing1 ,speaking1 ,dancing1 ,cooking2 also ,rules of ,etiquette1 ,the ,art of ,ventriloquism1 ,gymnastic ,exercises1 and ,the ,science of ,self-,defense1 etc41 etc4 #a ,napoleon's ,oraculum and ,dream ,book4 #b ,how to ,do ,tricks4 #c ,how to ,flirt4 #d ,how to ,dance4 #e ,how to ,make ,love4 #f ,how to ,become an ,athlete4 #g ,how to ,keep ,birds4 #h ,how to ,become a ,scientist4 #i ,how to ,become a ,ventriloquist4 #aj ,how to ,box4 #aa ,how to ,write ,love ,letters4 #ab ,how to ,write ,letters to ,ladies4 #ac ,how to ,do ,it2 or1 ,book of ,etiquette4 #ad ,how to ,make ,candy4 #ae ,how to ,become ,rich4 #af ,how to ,keep a ,window ,garden4 #ag ,how to ,dress4 #ah ,how to ,become ,beautiful4 #ai ,frank ,tousey's ,u4 ,s4 ,distance ,tables1 ,pocket ,companion and ,guide4 #bj ,how to ,entertain an ,evening ,party4 #ba ,how to ,hunt and ,fish4 #bb ,how to ,do ,second ,sight4 #bc ,how to ,explain ,dreams4 #bd ,how to ,write ,letters to ,gentlemen4 #be ,how to ,become a ,gymnast4 #bf ,how to ,row1 ,sail and ,build a ,boat4 #bg ,how to ,recite and ,book of ,recitations4 #bh ,how to ,tell ,fortunes4 #bi ,how to ,become an ,inventor4 #cj ,how to ,cook4 #ca ,how to ,become a ,speaker4 #cb ,how to ,ride a ,bicycle4 #cc ,how to ,behave4 #cd ,how to ,fence4 #ce ,how to ,play ,games4 #cf ,how to ,solve ,conundrums4 #cg ,how to ,keep ,house4 #ch ,how to ,become ,your ,own ,doctor4 #ci ,how to ,raise ,dogs1 ,poultry1 ,pigeons and ,rabbits4 #dj ,how to ,make and ,set ,traps4 #da ,the ,boys of ,new ,york ,end ,men's ,joke ,book4 #db ,the ,boys of ,new ,york ,stump ,speaker4 #dc ,how to ,become a ,magician4 #dd ,how to ,write in an ,album4 #de ,the ,boys of ,new ,york ,minstrel ,guide and ,joke ,book4 #df ,how to ,make and ,use ,electricity4 #dg ,how to ,break1 ,ride and ,drive a ,horse4 #dh ,how to ,build and ,sail ,canoes4 #di ,how to ,debate4 #ej ,how to ,stuff ,birds and ,animals4 #ea ,how to ,do ,tricks with ,cards4 #eb ,how to ,play ,cards4 #ec ,how to ,write ,letters4 #ed ,how to ,keep and ,manage ,pets4 #ee ,how to ,collect ,stamps and ,coins4 #ef ,how to ,become an ,engineer4 #eg ,how to ,make ,musical ,instruments4 #eh ,how to ,become a ,detective4 #ei ,how to ,make a ,magic ,lantern4 #fj ,how to ,become a ,photographer4 #fa ,how to ,become a ,bowler4 #fb ,how to ,become a ,west ,point ,military ,cadet4 #fc ,how to ,become a ,naval ,cadet4 #fd ,how to ,make ,electrical ,machines4 #fe ,muldoon's ,jokes4 #ff ,how to ,do ,puzzles4 #fg ,how to ,do ,electrical ,tricks4 #fh ,how to ,do ,chemical ,tricks4 #fi ,how to ,do ,sleight of ,hand4 #gj ,how to ,make ,magic ,toys4 #ga ,how to ,do ,mechanical ,tricks4 #gb ,how to ,do ,sixty ,tricks with ,cards4 #gc ,how to ,do ,tricks with ,numbers4 #gd ,how to ,write ,letters ,correctly4 #ge ,how to ,become a ,conjuror4 #gf ,how to ,tell ,fortunes by the ,hand4 #gg ,how to ,do ,forty ,tricks with ,cards4 #gh ,how to ,do the ,black ,art4 #gi ,how to ,become an ,actor4 #hj ,gus ,williams' ,joke ,book4 ,all the above books are for sale by newsdealers throughout the ,united ,states and ,canada1 or they will be sent1 post-paid1 to your address1 on receipt of #aj;c4 each4 ,send ,your ,name and ,address for ,our ,latest ,illustrated ,catalogue4 ,,frank ,,tousey1 ,publisher1 #bd ,,union ,,square1 ,,new ,,york4 99 99 99 99 99 ,transcriber's note3 ,the ,table of ,contents was created by the transcriber4 ,illustrations have been moved to paragraph breaks near where they are mentioned4 ,punctuation has been made consistent4 ,variations in spelling and hyphenation were retained as they appear in the original publication1 except that obvious typos have been corrected4 ,changes have been made as follows3 p4 #c3 ,caption added to figure 7,fig4 #a47 p4 #dj3 ,caption added to figure 7,fig4 #b47 p4 #da3 ,caption added to figure 7,fig4 #a47 p4 #ef3 ,caption added to figure 7,fig4 #b47