Teach Yourself the Slide Rule

1 Teach Yourself THE Slide RULEThe " Teach Yourself .." series of books (still published today by Hodder Stoughton) will be familiar to any British reader. One of their titles was " Teach Yourself the Slide Rule" byBurns Snodgrass , The author had founded the Unique Slide Rule Company in 1920. The book was published in 1954, the year of his death. The company wassubsequently managed by his son. Given the provenance of the author, it is not surprising that the book concentrates on Unique Slide rules . However since the company produced a widerange of rules it made a very comprehensive book was originally published by "The English Universities Press Ltd". The copyright is now held by "Hodder Stoughton", to whom I am grateful for permission to scan parts of thebook and put them on this web following is the original list of contents. From those sections with hyperlinks you can see which of them have been scanned and added to my site. I should add that I have notsimply scanned the pages and put them on the site as a graphics images but have interpreted them by Optical Character Recognition.

2 The advantage of this is that the files are smaller thanthe original graphics image and can be more easily printed. The disadvantage, but only for me, is that it is more labour intensive. I have also at times modified the format (for examplemoving lists of Slide movements into tables). As an Engineer married to an English graduate, I have been made aware that not only do engineers sometime use language in anidiosyncratic way but they are not always consistent in their use of language; this was case with Burns Snodgrass. I have not tried to improve his English nor add consistency (forexample, descriptions of Slide movements are sometimes given on separate lines and sometimes run together and separated by commas).The figures were taken from the original book; they often showed the two ends of a rule split over two 1. THE PRINCIPLE OF THE Slide RULEL inear and non-linear scales - numbering of the scales - reading the scales - multiplication and division of simple 2. FRACTIONS-DECIMALSF ractions, addition and subtraction - Multiplication and division - Decimals, Conversion of Decimal Fractions into ordinary Fractions - Addition and Subtraction - Multiplication andDivision - Contracted methods - Conversion of ordinary Fractions into Decimal Fractions - Recurring Decimals - Conversion of Recurring Decimals into ordinary 3.

3 THE MODERN Slide RULEP rotection of the Slide Rule - Component parts - C & D Scales - A & B Scales - Log Scale - The Cursor - Linear 4. C & D SCALESM ultiplication - Division - Multiplication and Division combined - Position of a Decimal 5. A & B SCALESS quares and Square Roots - Cubes and Cube Roots - Cube 6. LOG LOG SCALESE valuation of Powers and Roots - Common Logarithms - Natural 7. THE TRIGONOMETRICAL SCALESSine Scale - Tangent Scale - Solution of Triangles - Navigational Problems - Navigational Units and Formulae - Wind and Drift Problems - Interception Problems - Calculation of TrueTrack and 8. THE COMMERCIAL RULEThe Special Commercial Scales-Money Calculations - Discount Scale - The Monetary Rule - . Scales - Invoicing 9. THE PRECISION RULEThe Special C & D Scales - Multiplication - Division - Determining in which scale lies the 10. THE ELECTRICAL RULED ynamo and Motor Efficiencies - Volt Drop - Duplicate C & D Scales - Reciprocal Scale - Time Yourself the Slide Rulefile:///D|/SlideRules/WebPage/pdf/ (1 of 81) [02/09/2001 20:59:44]SECTION 11.

4 THE DUALISTIC RULED uplicated C & D Scales - Special 20" Scales for ordinary calculations - Squares and Square Roots - Cubes and Cube Roots - Log Log 12. THE BRIGHTON RULEThe ordinary Scales - Log Log Scales - Sine & Tan Scales - Cube Scale - Log 13. INDICES & LOGARITHMSI ndices - Multiplication and Division - Logarithms - Reading Log Tables - Multiplication and Division - All Bilogarithms - Powers and Roots - Logarithms with Negative Characteristics- Tables of Logarithms and 14. OTHER CALCULATING INSTRUMENTSC ylindrical Calculators - Circular Calculators - Watch type Calculators - Other 15. HISTORICAL NOTEI nvention of the Slide rules - Degree of Accuracy - Common Gauge Points - Marking Special Gauge 16. EXERCISESC ommerce - Energy and Power - Friction and Heat - Strength and Deflection of Beams - Strength of Shafts and Deflection of Springs - Electricity - Building - Surveying - Navigation TO PROBLEMS FOREWORDTHE present era is sometimes termed the mechanical age because so many operations which, in earlier days, were carried out slowly and often painfully by hand, are now performed bymachines with an enormous saving in time and Slide rule cannot be regarded as a modern invention since the first design dates from the early part of the seventeenth century, but every year sees additions and variations made andthe up-to-date instrument has, as might be expected, advanced greatly beyond the earlier types.

5 Every year a considerable number of Patent Specifications are lodged in the BritishPatents Office to give protection to the latest inventions in Slide rule technique, and we may say fairly that the Slide rule in its own field is keeping pace with modern mechanical Teach Yourself Book is published to increase the popularity of the Slide rule. It is hoped that it may help to remove the fallacy that there is something difficult or even mysteriousconnected with a simple instrument with which everybody who has calculations to make should be the technicians and artisans upon whom we so much depend for the maintenance and improvement of national prosperity, are many who have frequently to make would be hampered in their activities if the improvements we have referred to had not extended to expediting their work. The Slide rule and other instruments which give the samefacilities for rapid calculations, are covered by the term "Mechanical Calculation".It is unfortunate that, for some reasons not easy to see, the Slide rule is sometimes regarded as a difficult instrument with which to become proficient.

6 There is a tendency for some peopleto become facetious in their references to this simple instrument. Journalists and broadcasters are great offenders in this respect and some of their references are unbelievably absurd andshow a lack of elementary clumsy and unscientific system of monetary units and measures in weights, lengths, areas, etc., which have grown up and are still used in this country, give some slight difficulty inapplying the Slide rule to calculations in which they are involved and since the scales of Slide rules are, in most cases, subdivided in the decimal system, any notations of weights andmeasures which are similarly designed, such as the metric system, lend themselves readily to calculation by Slide shall find, however, that when working in our monetary system of pounds, shillings and pence, or in lengths in miles, yards and feet, or in any of our awkward units, the Slide rule canbe employed to simplify our work and give results quickly, and with a degree of accuracy sufficient for practical have said that, in general, Slide rule scales are subdivided in decimal fractions, and since there are still some people who cannot easily calculate in the decimal system, we give at anearly stage a simple explanation of the principles of this system.

7 Perhaps we need hardly add that any sections of this book which deal with matters with which the reader is quite familiarmay be glanced at and passed Yourself the Slide Rulefile:///D|/SlideRules/WebPage/pdf/ (2 of 81) [02/09/2001 20:59:44]We shall find that the underlying principle of the Slide rule is calculation by logarithms. Just as a man may be an expert motor-car driver without understanding the principles of theinternal-combustion engine and the mechanism of his car, so can a Slide rule be used without the slightest knowledge of logarithms. In fact, we hesitated at including the section onlogarithms, in case the mention of the term might cause discouragement and increase the sense of awe with which some people regard the Slide rule. The section on logarithms may bedisregarded entirely, and indeed we ask that it should be, on the first reading of this book, but when the rudiments of the Slide rule have been mastered - and again we stress the simplicityof these - it may be that some readers will find interest and advantage in learning something of the first principles of "logs" - one of the most fascinating parts of elementary factor which has contributed to the reluctance of people to purchase a Slide rule lies in the erroneous impression that it is a costly instrument.

8 Naturally enough, people are averseto paying two or three pounds for an instrument which they fear may be of little use to them. Inexpensive Slide rules have been available in this country for over thirty years, and theirmakers claim that for accuracy and utility they are equal to the more expensive varieties which have been manufactured for a much longer period. The first "Unique" Slide rule, the 10"log-log model, was produced at a popular price for students. Its introduction was welcomed, and it met with success. There are now about a score of different Slide rules in the "Unique"range, and sales have progressively increased, and it may fairly be said that this make of rule is now the "best seller" in this country. "Unique" Slide rules carry all the useful scales,including the log-log scale, in most models. In the expensive type of rule the inclusion of the log-log scale means a much higher-priced instrument than the "standard" or ordinary log-log scale in the "Unique" range is included at no increase in the cost of the rule.

9 The makers of "Unique" Slide rules introduced a new technique in manufacture by printing thescales and coating them with transparent plastic material. This important change allowed of a great reduction in the manufacturing cost as compared with the older method of separatelydividing the book, however, is not published primarily to boost any particular make of Slide rule. All Slide rules are difficult to manufacture, and in most cases are honestly worth the pricescharged for them. Some shopkeepers charge more than the recognised retail prices fixed by the manufacturers, and purchasers should be vigilant and resist any attempt at this sort would, with all respect, urge members of the teaching profession to make more effective efforts to introduce the Slide rule into schools. The proper place to become acquainted withthis invaluable time-saver is in the classrooms of the primary schools; normal boys and girls of the age of 13 or 14 years are able to attain proficiency in its use.

10 More often than not thestudent does not become acquainted with the Slide rule until he or she reaches a technical school or college, and even in such institutions the Slide rule is by no means the universal andeveryday instrument it deserves to writer has had long experience of teaching in a technical college, and has never had the least difficulty in arousing interest in the application of the Slide rule to practical was never any necessity to urge students to adopt the rule; directly a Slide rule appeared in a classroom and was demonstrated, students expressed the desire to acquire one, andwithin a week or two the majority had done so. A few minutes devoted to instruction were sufficient to Teach the fundamentals. We know that the Slide rule is used in a number ofprimary and central schools by teachers who think as we do. Unfortunately, we also know that even in some grammar and secondary schools a Slide rule is almost would particularly direct attention to Section 8, which deals with Slide rules designed for commercial calculations.