,transcriber's ,notes ,conventional mathematical notation requires specialized fonts and typesetting conventions4 ,i have adopted modern computer programming notation using only ,,ascii characters4 ,the square root of #i is thus rendered as squareroot7#i7 and the square of #i is square7#i74 #aj divided by #e is 7#aj_/e7 and #aj multiplied by #e is 7#aj 99 #e 74 ,by the time ,i finished engineering school in #aifc1 the slide rule was a well worn tool of my trade4 ,i did not use an electronic calculator for another ten years4 ,consider that my predecessors had little else to use--think ,boulder ,dam 7with all its electrical1 mechanical and construction calculations74 ,rather than dealing with elaborate rules for positioning the decimal point1 ,i was taught to first scale the factors and deal with the decimal position separately4 ,for example3 #abcj 99 4#jjjjic #a4bc;,e#c 99 #i4c;,e-#e #a4bc;,e#c means multiply #a4bc by #aj to the power #c4 #i4c;,e-#e means multiply #i4c by #j4a to the power #e or #aj to the power -#e4 ,the computation is thus #a4bc 99 #i4c 99 #a;,e#c 99 #a;,e-#e ,the exponents are simply added4 #a4bc 99 #i4c 99 #a;,e-#b #aa4d 99 #a;,e-#b 4#aad ,when taking roots1 divide the exponent by the root4 ,the square root of #a;,e#f is #a;,e#c ,the cube root of #a;,e#ab is #a;,e#d4 ,when taking powers1 multiply the exponent by the power4 ,the cube of #a;,e#e is #a;,e#ae4 ,end ,transcriber's ,notes ,,instructions for using a ,,slide ,,rule ,,save ,,time6 ,,do ,,the ,,following ,,instantly ,,without ,,paper ,,and ,,pencil ,,multiplication ,,division ,,reciprocal ,,values ,,squares ,,cubes ,,extraction ,,of ,,square ,,root ,,extraction ,,of ,,cube ,,root ,,diameter ,,or ,,area ,,of ,,circle ,illustration3 ,two images of a slide rule4 ,,instructions ,,for ,,using ,a ,,slide ,,rule ,the slide rule is a device for easily and quickly multiplying1 dividing and extracting square root and cube root4 ,it will also perform any combination of these processes4 ,on this account1 it is found extremely useful by students and teachers in schools and colleges1 by engineers1 architects1 draftsmen1 surveyors1 chemists1 and many others4 ,accountants and clerks find it very helpful when approximate calculations must be made rapidly4 ,the operation of a slide rule is extremely easy1 and it is well worth while for anyone who is called upon to do much numerical calculation to learn to use one4 ,it is the purpose of this manual to explain the operation in such a way that a person who has never before used a slide rule may teach himself to do so4 ,,description ,,of ,,slide ,,rule ,the slide rule consists of three parts 7see figure #a74 ,b is the body of the rule and carries three scales marked ,a1 ,d and ,k4 ,s is the slider which moves relative to the body and also carries three scales marked ,b1 ,,ci and ,c4 ,r is the runner or indicator and is marked in the center with a hair-line4 ,the scales ,a and ,b are identical and are used in problems involving square root4 ,scales ,c and ,d are also identical and are used for multiplication and division4 ,scale ,k is for finding cube root4 ,scale ,,ci1 or ,c-inverse1 is like scale ,c except that it is laid off from right to left instead of from left to right4 ,it is useful in problems involving reciprocals4 ,,multiplication ,we will start with a very simple example3 ,example #a3 #b 99 #c #f ,to prove this on the slide rule1 move the slider so that the #a at the left-hand end of the ,c scale is directly over the large #b on the ,d scale 7see figure #a74 ,then move the runner till the hair-line is over #c on the ,c scale4 ,read the answer1 #f1 on the ,d scale under the hair-line4 ,now1 let us consider a more complicated example3 ,example #b3 #b4ab 99 #c4af #f4gj ,as before1 set the #a at the left-hand end of the ,c scale1 which we will call the left-hand index of the ,c scale1 over #b4ab on the ,d scale 7,see figure #b74 ,the hair-line of the runner is now placed over #c4af on the ,c scale and the answer1 #f4gj1 read on the ,d scale4 ,,method ,,of ,,making ,,settings ,in order to understand just why #b4ab is set where it is 7figure #b71 notice that the interval from #b to #c is divided into #aj large or major divisions1 each of which is1 of course1 equal to one-tenth 7#j4a7 of the amount represented by the whole interval4 ,the major divisions are in turn divided into #e small or minor divisions1 each of which is one-fifth or two-tenths 7#j4b7 of the major division1 that is #j4jb of the whole interval4 ,therefore1 the index is set above #b #a major division #a minor division #b #j4a #j4jb #b4ab4 ,in the same way we find #c4af on the ,c scale4 ,while we are on this subject1 notice that in the interval from #a to #b the major divisions are marked with the small figures #a to #i and the minor divisions are #j4a of the major divisions4 ,in the intervals from #b to #c and #c to #d the minor divisions are #j4b of the major divisions1 and for the rest of the ,d 7or ,c7 scale1 the minor divisions are #j4e of the major divisions4 ,reading the setting from a slide rule is very much like reading measurements from a ruler4 ,imagine that the divisions between #b and #c on the ,d scale 7figure #b7 are those of a ruler divided into tenths of a foot1 and each tenth of a foot divided in #e parts #j4jb of a foot long4 ,then the distance from one on the left-hand end of the ,d scale 7not shown in figure #b7 to one on the left-hand end of the ,c scale would he #b4ab feet4 ,of course1 a foot rule is divided into parts of uniform length1 while those on a slide rule get smaller toward the right-hand end1 but this example may help to give an idea of the method of making and reading settings4 ,now consider another example4 ,example #c;a3 #b4ab 99 #g4ce #ae4f ,if we set the left-hand index of the ,c scale over #b4ab as in the last example1 we find that #g4ce on the ,c scale falls out beyond the body of the rule4 ,in a case like this1 simply use the right-hand index of the ,c scale4 ,if we set this over #b4ab on the ,d scale and move the runner to #g4ce on the ,c scale we read the result #ae4f on the ,d scale under the hair-line4 ,now1 the question immediately arises1 why did we call the result #ae4f and not #a4ef8 ,the answer is that the slide rule takes no account of decimal points4 ,thus1 the settings would be identical for all of the following products3 ,example #c3 a-- #b4ab 99 #g4ce #ae4f b-- #ba4b 99 #g4ce #aef4j c-- #bab 99 #gc4e #aefjj4 d-- #b4ab 99 4#jgce 4#aef e-- 4#jjbab 99 #gce 4#jaef ,the most convenient way to locate the decimal point is to make a mental multiplication using only the first digits in the given factors4 ,then place the decimal point in the slide rule result so that its value is nearest that of the mental multiplication4 ,thus1 in example #c;a above1 we can multiply #b by #g in our heads and see immediately that the decimal point must be placed in the slide rule result #aef so that it becomes #ae4f which is nearest to #ad4 ,in example #c;b 7#bj 99 #g #adj71 so we must place the decimal point to give #aef4 ,the reader can readily verify the other examples in the same way4 ,since the product of a number by a second number is the same as the product of the second by the first1 it makes no difference which of the two numbers is set first on the slide rule4 ,thus1 an alternative way of working example #b would be to set the left-hand index of the ,c scale over #c4af on the ,d scale and move the runner to #b4ab on the ,c scale and read the answer under the hair-line on the ,d scale4 ,the ,a and ,b scales are made up of two identical halves each of which is very similar to the ,c and ,d scales4 ,multiplication can also be carried out on either half of the ,a and ,b scales exactly as it is done on the ,c and ,d scales4 ,however1 since the ,a and ,b scales are only half as long as the ,c and ,d scales1 the accuracy is not as good4 ,it is sometimes convenient to multiply on the ,a and ,b scales in more complicated problems as we shall see later on4 ,a group of examples follow which cover all the possible combination of settings which can arise in the multiplication of two numbers4 ,example #d3 #bj 99 #c #fj #e3 #he 99 #b #agj #f3 #de 99 #ce #aege #g3 #aea 99 #db #fcdb #h3 #f4e 99 #ae #ig4e #i3 4#cd 99 4#jh 4#jbgb #aj3 #ge 99 #bf #aiej #aa3 4#jjjed 99 #a4d 4#jjjgef #ab3 #aa4a 99 #b4g #bi4ig #ac3 #a4ja 99 #ed #ed4e #ad3 #c4ad 99 #be #gh4e ,,division ,since multiplication and division are inverse processes1 division on a slide rule is done by making the same settings as for multiplication1 but in reverse order4 ,suppose we have the example3 ,example #ae3 7#f4gj _/ #b4ab7 #c4af ,set indicator over the dividend #f4gj on the ,d scale4 ,move the slider until the divisor #b4ab on the ,c scale is under the hair-line4 ,then read the result on the ,d scale under the left-hand index of the ,c scale4 ,as in multiplication1 the decimal point must be placed by a separate process4 ,make all the digits except the first in both dividend and divisor equal zero and mentally divide the resulting numbers4 ,place the decimal point in the slide rule result so that it is nearest to the mental result4 ,in example #ae1 we mentally divide #f by #b4 ,then we place the decimal point in the slide rule result #caf so that it is #c4af which is nearest to #c4 ,a group of examples for practice in division follow3 ,example #af3 #cd _/ #b #ag #ag3 #di _/ #g #g #ah3 #acb _/ #ab #aa #ai3 #dhj _/ #af #cj #bj3 #a4je _/ #ce 4#jc #ba3 #d4cb _/ #ab 4#cf #bb3 #e4bc _/ #f4ae 4#he #bc3 #ag4a _/ #d4e #c4h #bd3 #ahie _/ #f4jf #cac #be3 #de _/ 4#jag #bfdg ,,the ,,ci ,,scale ,if we divide one 7#a7 by any number the answer is called the reciprocal of the number4 ,thus1 one-half is the reciprocal of two1 one-quarter is the reciprocal of four4 ,if we take any number1 say #ad1 and multiply it by the reciprocal of another number1 say #b1 we get3 ,example #bf3 #ad 99 7#a_/b7 #g which is the same as #ad divided by two4 ,this process can be carried out directly on the slide rule by use of the ,,ci scale4 ,numbers on the ,,ci scale are reciprocals of those on the ,c scale4 ,thus we see that #b on the ,,ci scale comes directly over #j4e or #a_/b on the ,c scale4 ,similarly #d on the ,,ci scale comes over #j4be or #a_/d on the ,c scale1 and so on4 ,to do example #bf by use of the ,,ci scale1 proceed exactly as if you were going to multiply in the usual manner except that you use the ,,ci scale instead of the ,c scale4 ,first set the left-hand index of the ,c scale over #ad on the ,d scale4 ,then move the indicator to #b on the ,,ci scale4 ,read the result1 #g1 on the ,d scale under the hair-line4 ,this is really another way of dividing4 ,,the ,,reader ,,is ,,advised ,,to ,,work ,,examples #af ,,to #be ,,over ,,again ,,by ,,use ,,of ,,the ,,ci ,,scale4 ,,squaring ,,and ,,square ,,root ,if we take a number and multiply it by itself we call the result the square of the number4 ,the process is called squaring the number4 ,if we find the number which1 when multiplied by itself is equal to a given number1 the former number is called the square root of the given number4 ,the process is called extracting the square root of the number4 ,both these processes may be carried out on the ,a and ,d scales of a slide rule4 ,for example3 ,example #bg3 #d 99 #d square7 #d 7 #af ,set indicator over #d on ,d scale4 ,read #af on ,a scale under hair-line4 ,example #bh3 square7 #be4d 7 #fdf4j ,the decimal point must be placed by mental survey4 ,we know that square7 #be4d 7 must be a little larger than square7 #be 7 #fbe so that it must be #fdf4j4 ,to extract a square root1 we set the indicator over the number on the ,a scale and read the result under the hair-line on the ,d scale4 ,when we examine the ,a scale we see that there are two places where any given number may be set1 so we must have some way of deciding in a given case which half of the ,a scale to use4 ,the rule is as follows3 7a7 ,if the number is greater than one4 ,for an odd number of digits to the left of the decimal point1 use the left-hand half of the ,a scale4 ,for an even number of digits to the left of the decimal point1 use the right-hand half of the ,a scale4 7b7 ,if the number is less than one4 ,for an odd number of zeros to the right of the decimal point before the first digit not a zero1 use the left-hand half of the ,a scale4 ,for none or any even number of zeros to the right of the decimal point before the first digit not a zero1 use the right-hand half of the ,a scale4 ,example #bi3 squareroot7 #aeg 7 #ab4e ,since we have an odd number of digits set indicator over #aeg on left-hand half of ,a scale4 ,read #ab4e on the ,d scale under hair-line4 ,to check the decimal point think of the perfect square nearest to #aeg4 ,it is #ab 99 #ab #add1 so that squareroot7#aeg7 must be a little more than #ab or #ab4e4 ,example #cj3 squareroot7 4#jjcg 7 4#jfjh ,in this number we have an even number of zeros to the right of the decimal point1 so we must set the indicator over #cg on the right-hand half of the ,a scale4 ,read #fjh under the hair-line on ,d scale4 ,to place the decimal point write3 squareroot7 4#jjcg 7 squareroot7 #cg_/ajjjj 7 #a_/ajj squareroot7 #cg 7 ,the nearest perfect square to #cg is #f 99 #f #cf1 so the answer should be a little more than #j4jf or 4#jfjh4 ,all of what has been said about use of the ,a and ,d scales for squaring and extracting square root applies equally well to the ,b and ,c scales since they are identical to the ,a and ,d scales respectively4 ,a number of examples follow for squaring and the extraction of square root4 ,example #ca3 square7 #b 7 #d #cb3 square7 #ae 7 #bbe #cc3 square7 #bf 7 #fgf #cd3 square7 #ai4fe 7 #chf #ce3 squareroot7 #fd 7 #h #cf3 squareroot7 #f4d 7 #b4ec #cg3 squareroot7 #dih 7 #bb4e #ch3 squareroot7 #bejj 7 #ej #ci3 squareroot7 4#af 7 4#jd #dj3 squareroot7 4#jc 7 4#agc ,,cubing ,,and ,,cube ,,root ,if we take a number and multiply it by itself1 and then multiply the result by the original number we get what is called the cube of the original number4 ,this process is called cubing the number4 ,the reverse process of finding the number which1 when multiplied by itself and then by itself again1 is equal to the given number1 is called extracting the cube root of the given number4 ,thus1 since #e 99 #e 99 #e #abe1 #abe is the cube of #e and #e is the cube root of #abe4 ,to find the cube of any number on the slide rule set the indicator over the number on the ,d scale and read the answer on the ,k scale under the hair-line4 ,to find the cube root of any number set the indicator over the number on the ,k scale and read the answer on the ,d scale under the hair-line4 ,just as on the ,a scale1 where there were two places where you could set a given number1 on the ,k scale there are three places where a number may be set4 ,to tell which of the three to use1 we must make use of the following rule4 7a7 ,if the number is greater than one4 ,for #a1 #d1 #g1 #aj1 etc41 digits to the left of the decimal point1 use the left-hand third of the ,k scale4 ,for #b1 #e1 #h1 #aa1 etc41 digits to the left of the decimal point1 use the middle third of the ,k scale4 ,for #c1 #f1 #i1 #ab1 etc41 digits to the left of the decimal point use the right-hand third of the ,k scale4 7b7 ,if the number is less than one4 ,we now tell which scale to use by counting the number of zeros to the right of the decimal point before the first digit not zero4 ,if there are #b1 #e1 #h1 #aa1 etc41 zeros1 use the left-hand third of the ,k scale4 ,if there are #a1 #d1 #g1 #aj1 etc41 zeros1 then use the middle third of the ,k scale4 ,if there are no zeros or #c1 #f1 #i1 #ab1 etc41 zeros1 then use the right-hand third of the ,k scale4 ,for example3 ,example #da3 cuberoot7 #ahe 7 #e4gj ,since there are #c digits in the given number1 we set the indicator on #ahe in the right-hand third of the ,k scale1 and read the result #egj on the ,d scale4 ,we can place the decimal point by thinking of the nearest perfect cube1 which is #abe4 ,therefore1 the decimal point must be placed so as to give #e4gj1 which is nearest to #e1 the cube root of #abe4 ,example #db3 cuberoot7 4#jcd 7 4#cbd ,since there is one zero between the decimal point and the first digit not zero1 we must set the indicator over #cd on the middle third of the ,k scale4 ,we read the result #cbd on the ,d scale4 ,the decimal point may be placed as follows3 cuberoot7 4#jcd 7 cuberoot7 #cd_/ajjj 7 #a_/aj cuberoot7 #cd 7 ,the nearest perfect cube to #cd is #bg1 so our answer must be close to one-tenth of the cube root of #bg or nearly #j4c4 ,therefore1 we must place the decimal point to give #j4cbd4 ,a group of examples for practice in extraction of cube root follows3 ,example #dc3 cuberoot7 #fd 7 #d #dd3 cuberoot7 #h 7 #b #de3 cuberoot7 #cdc 7 #g #df3 cuberoot7 4#jjjgae 7 4#jhid #dg3 cuberoot7 4#jjgae 7 4#aic #dh3 cuberoot7 4#jgae 7 4#dae #di3 cuberoot7 4#eaf 7 4#hjc #ej3 cuberoot7 #bg4h 7 #c4jc #ea3 cuberoot7 #e4di 7 #a4gf #eb3 cuberoot7 #hg4a 7 #d4dc ,,the #a4e ,,and #b_/c ,,power ,if the indicator is set over a given number on the ,a scale1 the number under the hair-line on the ,k scale is the #a4e power of the given number4 ,if the indicator is set over a given number on the ,k scale1 the number under the hair-line on the ,a scale is the #b_/c power of the given number4 ,,combinations ,,of ,,processes ,a slide rule is especially useful where some combination of processes is necessary1 like multiplying #c numbers together and dividing by a third4 ,operations of this sort may be performed in such a way that the final answer is obtained immediately without finding intermediate results4 #a4 ,multiplying several numbers together4 ,for example1 suppose it is desired to multiply #d 99 #h 99 #f4 ,place the right-hand index of the ,c scale over #d on the ,d scale and set the indicator over #h on the ,c scale4 ,now1 leaving the indicator where it is1 move the slider till the right-hand index is under the hairline4 ,now1 leaving the slider where it is1 move the indicator until it is over #f on the ,c scale1 and read the result1 #aib1 on the ,d scale4 ,this may be continued indefinitely1 and so as many numbers as desired may be multiplied together4 ,example #ec3 #b4cb 99 #aed 99 4#jcge 99 4#ef #g4ed #b4 ,multiplication and division4 ,suppose we wish to do the following example3 ,example #ed3 7#d 99 #ae7 _/ #b4e #bd ,first divide #d by #b4e4 ,set indicator over #d on the ,d scale and move the slider until #b4e is under the hair-line4 ,the result of this division1 #a4f1 appears under the left-hand index of the ,c scale4 ,we do not need to write it down1 however1 but we can immediately move the indicator to #ae on the ,c scale and read the final result #bd on the ,d scale under the hair-line4 ,let us consider a more complicated problem of the same type3 ,example #ee3 7#cj_/g4e7 99 7#b_/d7 99 7#d4e_/e7 99 7#a4e_/c7 4#i ,first set indicator over #cj on the ,d scale and move slider until #g4e on the ,c scale comes under the hairline4 ,the intermediate result1 #d1 appears under the right-hand index of the ,c scale4 ,we do not need to write it down but merely note it by moving the indicator until the hair-line is over the right-hand index of the ,c scale4 ,now we want to multiply this result by #b1 the next factor in the numerator4 ,since two is out beyond the body of the rule1 transfer the slider till the other 7left-hand7 index of the ,c scale is under the hair-line1 and then move the indicator to #b on the ,c scale4 ,thus1 successive division and multiplication is continued until all the factors have been used4 ,the order in which the factors are taken does not affect the result4 ,with a little practice you will learn to take them in the order which will require the fewest settings4 ,the following examples are for practice3 ,example #ef3 7#f_/c4e7 99 7#d_/e7 99 7#c4e_/b4d7 99 7#b4h_/g7 4#h ,example #eg3 #ceb 99 7#bgc_/bed7 99 7#gfj_/gfh7 #cgd ,an alternative method of doing these examples is to proceed exactly as though you were multiplying all the factors together1 except that whenever you come to a number in the denominator you use the ,,ci scale instead of the ,c scale4 ,the reader is advised to practice both methods and use whichever one he likes best4 #c4 ,the area of a circle4 ,the area of a circle is found by multiplying #c4adaf,,pi by the square of the radius or by one-quarter the square of the diameter ,formula3 ,a ,,pi 99 square7 ,r 7 ,a ,,pi 99 7 square7 ,d 7 _/ #d 7 ,example #eh3 ,the radius of a circle is #j4be inches2 find its area4 ,area ,,pi 99 square7#j4be7 #j4aif square inches4 ,set left-hand index of ,c scale over #j4be on ,d scale4 square7#j4be7 now appears above the left-hand index of the ,b scale4 ,this can be multiplied by ,,pi by moving the indicator to ,,pi on the ,b scale and reading the answer 4#aif on the ,a scale4 ,this is an example where it is convenient to multiply with the ,a and ,b scales4 ,example #ei3 ,the diameter of a circle is #h4a feet4 ,what is its area8 ,area 7,,pi _/ #d7 99 square7#h4a7 4#ghed 99 square7#h4a7 #ea4g sq4 inches4 ,set right-hand index of the ,c scale over #h4a on the ,d scale4 ,move the indicator till hair-line is over 4#ghed 7the special long mark near #h7 at the right hand of the ,b scale4 ,read the answer under the hair-line on the ,a scale4 ,another way of finding the area of a circle is to set #ghed on the ,b scale to one of the indices of the ,a scale1 and read the area from the ,b scale directly above the given diameter on the ,d scale4 #d4 ,the circumference of a circle4 ,set the index of the ,b scale to the diameter and read the answer on the ,a scale opposite ,,pi on the ,b scale ,formula3 ,c ,,pi 99 ,d ,c #b 99 ,,pi 99 ,r ,example #fj3 ,the diameter of a circle is #a4ed inches1 what is its circumference8 ,set the left-hand index of the ,b scale to #a4ed on the ,a scale4 ,read the circumference #d4he inches above ,,pi on the ,b scale4 ,,examples ,,for ,,practice #fa3 ,what is the area of a circle #cb-a_/b inches in diameter8 ,answer #hcj sq4 inches #fb3 ,what is the area of a circle #bd inches in diameter8 ,answer #deb sq4 inches #fc3 ,what is the circumference of a circle whose diameter is #ie feet8 ,answer #bih ft4 #fd3 ,what is the circumference of a circle whose diameter is #c4fe inches8 ,answer #aa4e inches #e4 ,ratio and ,proportion4 ,example #fe3 #c 3 #g 3 3 #d 3 ,x or 7#c_/g7 7#d_/x7 ,find ,x ,set #c on ,c scale over #g on ,d scale4 ,read ,x on ,d scale under #d on ,c scale4 ,in fact1 any number on the ,c scale is to the number directly under it on the ,d scale as #c is to #g4 ,,practical ,,problems ,,solved ,,by ,,slide ,,rule #a4 ,discount4 ,a firm buys a typewriter with a list price of #aej1 subject to a discount of #bj and #aj4 ,how much does it pay8 ,a discount of #bj means #j4h of the list price1 and #aj more means #j4h ,x #j4i ,x #aej #ajh4 ,to do this on the slide rule1 put the index of the ,c scale opposite #h on the ,d scale and move the indicator to #i on the ,c scale4 ,then move the slider till the right-hand index of the ,c scale is under the hairline4 ,now1 move the indicator to #aej on the ,c scale and read the answer #ajh on the ,d scale4 ,notice that in this1 as in many practical problems1 there is no question about where the decimal point should go4 #b4 ,sales ,tax4 ,a man buys an article worth #ab and he must pay a sales tax of #a4e4 ,how much does he pay8 ,a tax of #a4e means he must pay #a4jae 99 #ab4jj4 ,set index of ,c scale at #a4jae on ,d scale4 ,move indicator to #ab on ,c scale and read the answer #ab4ah on the ,d scale4 ,a longer but more accurate way is to multiply #ab 99 4#jae and add the result to #ab4 #c4 ,unit ,price4 ,a motorist buys #ag gallons of gas at #ai4e cents per gallon4 ,how much does he pay8 ,set index of ,c scale at #ag on ,d scale and move indicator to #ai4e on ,c scale and read the answer #c4cb on the ,d scale4 #d4 ,gasoline ,mileage4 ,an automobile goes #age miles on #ab gallons of gas4 ,what is the average gasoline consumption8 ,set indicator over #age on ,d scale and move slider till #ab is under hair-line4 ,read the answer #ad4f miles per gallon on the ,d scale under the left-hand index of the ,c scale4 #e4 ,average ,speed4 ,a motorist makes a trip of #bef miles in #g4e hours4 ,what is his average speed8 ,set indicator over #bef on ,d scale4 ,move slider till #g4e on the ,c scale is under the hair-line4 ,read the answer #cd4b miles per hour under the right-hand index of the ,c scale4 #f4 ,decimal ,parts of an ,inch4 ,what is #e_/af of an inch expressed as decimal fraction8 ,set #af on ,c scale over #e on ,d scale and read the result 4#cabe inches on the ,d scale under the left-hand index of the ,c scale4 #g4 ,physics4 ,a certain quantity of gas occupies #abjj cubic centimeters at a temperature of #ae degrees ,c and #gdj millimeters pressure4 ,what volume does it occupy at #j degrees ,c and #gfj millimeters pressure8 ,volume #abjj ,x 7#gdj_/gfj7 99 7#bgc_/bhh7 #aajj cubic cm4 ,set #gfj on ,c scale over #ab on ,d scale4 ,move indicator to #gdj on ,c scale4 ,move slider till #bhh on ,c scale is under hair-line4 ,move indicator to #bgc on ,c scale4 ,read answer1 #aaaj1 under hair-line on ,d scale4 #h4 ,chemistry4 ,how many grams of hydrogen are formed when #hj grams of zinc react with sufficient hydrochloric acid to dissolve the metal8 7#hj _/ ,x 7 7 #fe4d _/ #b4ja7 ,set #fe4d on ,c scale over #b4ja on ,d scale4 ,read ,x #b4df grams under #hj on ,c scale4 ,in conclusion1 we want to impress upon those to whom the slide rule is a new method of doing their mathematical calculations1 and also the experienced operator of a slide rule1 that if they will form a habit of1 and apply themselves to1 using a slide rule at work1 study1 or during recreations1 they will be well rewarded in the saving of time and energy4 ,,always ,,have ,,your ,,slide ,,rule ,,and ,,instruction ,,book ,,with ,,you1 the same as you would a fountain pen or pencil4 ,the present day wonders of the twentieth century prove that there is no end to what an individual can accomplish--the same applies to the slide rule4 ,you will find after practice that you will be able to do many specialized problems that are not outlined in this instruction book4 ,it depends entirely upon your ability to do what we advocate and to be slide-rule conscious in all your mathematical problems4 ,,conversion ,,factors #a4 ,length #a mile #ebhj feet #agfj yards #a inch #b4ed centimeters #a meter #ci4cg inches #b4 ,weight 7or ,mass7 #a pound #af ounces #j4decf kilograms #a kilogram #b4b pounds #a long ton #bbdj pounds #a short ton#bjjj pounds #c4 ,volume #a liquid quart #j4ide litres #a litre #a4jf liquid quarts #a ,u4 ,s4 gallon #d quarts #bca cubic inches #d4 ,angular ,measure #c4ad radians ,,pi radians #ahj degrees #a radian #eg4cj degrees #e4 ,pressure #gfj millimeters of mercury #ad4g pounds per square inch #f4 ,power #a horse power #eej foot pounds per second #gdf watts #g4 ,miscellaneous #fj miles per hour #hh feet per second #ihj centimeters per second per second #cb4b feet per second per second acceleration of gravity4 #a cubic foot of water weighs #fb4d pounds #a gallon of water weighs #h4cd pounds ,printed in ,u4 ,s4 ,a4 ,,instructions ,,for ,,using ,a ,,slide ,,rule ,,copyrighted ,,by ,w4 ,,stanley ,,co4 ,commercial ,trust ,building1 ,philadelphia1 ,pa4