NATURE 



217 



THURSDAY, JULY 8, 1897. 



BICYCLES AND TRICYCLES. 

 Bicycles and Tricycles. A/t Elementary Treatise on 

 their Design and Construction. With Examples and 

 Tables. By Archibald Sharp, B.Sc, Whitworth 

 Scholar, Associate Member of the Institution of Civil 

 Engineers, Mitglied des vereines Deutscher in- 

 genieure, Instructor in Engineering Design at the 

 Central Technical College, South Kensington. With 

 numerous Illustrations. Octavo. Pp. .\viii + 536. 565 

 Figures. Index. (London, New York, and Bombay : 

 Longmans, Green, and Co., 1896.) 



IT is difficult to know who to congratulate most, the 

 author of this really valuable work or the public, 

 especially the cycle manufacturing branch of it, for 

 whose edification and improvement it has been written. 



The second paragraph of the author's preface so aptly 

 summarises the need for such a book that, in spite of its 

 length, it is worth quoting in full. 



"The present type of rear-driving bicycle is the 

 outcome of about ten years' practical experience. The 

 old ' Ordinary,' with the large front driving-wheel, 

 straight fork, and curved backbone, was a model 

 of simplicity of construction, but with the introduc- 

 tion of a smaller driving-wheel, driven by gearing 

 from the pedals, and the consequent greater complexity 

 of the frame, there was more scope for variation of form 

 of the machine. Accordingly, till a few years ago, a great 

 variety of bicycles were on the market, many of them 

 utterly wanting in scientific design. Out of these, the 

 present day rear-driving bicycle, with diamond frame, 

 extended wheel base, and long socket-steering head — the 

 fittest— has survived. A better technical education on 

 the part of bicycle manufacturers and their customers 

 might have saved them a great amount of trouble and 

 expense. Two or three years ago, when there seemed a 

 chance of the dwarf front-driving bicycle coming into 

 popular favour, the same variety in design of frame was 

 to be seen ; and even now with tandem bicycles there 

 are many frames on the market which evince on the part 

 of their designers utter ignorance of mechanical science. 

 If the present work is the means of influencing makers, or 

 purchasers, to such an extent as to make the manufacture 

 and sale of such mechanical monstrosities in the future 

 more difficult than it has been in the past, the author will 

 regard his labours as having been entirely successful." 



It is merely necessary for any one to go to one of the 

 annual cycle shows and to overhear the, no doubt, honestly 

 attempted explanation of the advantages of some hope- 

 less device, and the apparent satisfaction with which some 

 of these plausible follies are devoured by a section of the 

 public, to feel that Mr. Sharp has expressed himself with 

 too much enthusiasm. Perpetual motion is no more dead 

 now than it ever was ; in fact, in consequence of the 

 extraordinary successes in the cycle business during the 

 past year or so, vendors of schemes for creating power 

 are doing a better business than ever. If fifty books as 

 excellent as the one under review were in their hands, 

 these people would always rise superior to the absurd 

 limitations which mere conventional mechanicians re- 

 cognise. 



The real value of Mr. Sharp's book will, in the main, 

 be felt by the manufacturers, who, in many cases, pos- 

 sessed of mechanical instinct, but without sound technical 

 training, are honestly attempting to improve their 

 NO. 1445. VOL. 56] 



produce. If any of them is able to handle elementary 

 algebra and geometry, which is all that is asked of the 

 reader, he will be taken in the first portion of the book 

 through a course of instruction in which the principles, 

 so far as they are required for cycle design, of kine- 

 matics, statics, dynamics, friction, and the stresses and 

 strains in simple and compound structures are explained 

 in a manner which is admirable. If he is not able to 

 make use of the very elementary mathematical processes 

 employed, he may yet follow much of the reasoning. 



The first of the three parts into which the book is divided, 

 is in reality itself an excellent text-book which has the 

 unusual merit that it is not written for students or to 

 meet a syllabus, but simply with the object of enabling 

 any ordinary person with the usual school education to 

 obtain a clear insight into the principles of construction 

 and design. If there is one chapter in this part which 

 will be valued more than others it is the one on bending, 

 in which the theory is explained and then applied to the 

 case of ordinary beams and tubes of various sections. 

 The numerical tables in which the sectional areas, weights 

 per foot run, and moduli of bending resistances of solid 

 bars and of steel tubes, should be of use to the designer. 



The second part of the book, in which the well-known 

 machines which have taken their part in the evolution 

 of the modern cycle are described, while interesting in 

 many ways, is of decidedly less utility than the first or 

 last, or rather it would be so if it were not fortified by 

 chapters on stability of cycles, steering of cycles, resist- 

 ance of cycles, and gearing in general. 



The third part, which is the largest, is simply one on 

 details ; but where there are such a host of details as 

 there are in a bicycle, and each becomes the subject ot 

 an essay, the proportion assigned cannot be considered 

 too large. For instance, seventy-two pages are devoted 

 to the frame and to the stresses to which it is subjected. 

 Wheels, bearings, chain and other gearing, tyres, pedals, 

 cranks, springs, saddles and brakes are all discussed at 

 length. 



Before examining this book more in detail, it may be 

 worth while to say that Mr. Sharp is well known as an 

 ingenious and sound mechanical engineer, so that readers 

 of his book may be well assured that if they come across 

 any statement which seems at variance with their ideas, 

 or with what appears to be common sense, or even with 

 the convictions of racing men, the statement is never- 

 theless one to be considered carefully. 



The chief doubt which occurs to the writer of this 

 review is whether the first 1 10 pages should have been 

 written at all. This part is, after all, merely a text-book 

 of mechanics, put together, it is true, in such a manner as 

 to give prominence to the problems which a study of the 

 cycle presents, but nevertheless a text-book abstract and 

 black-boardy. If it is desirable that such a text-book 

 should be incorporated in a work on bicycles and tricycles, 

 then no fault is to be found with the substance of it, for it 

 is clear, accurate, and to the point. At p. no the all- 

 important question of the stiffness of tubes is reached. 

 This is gone into at some length, both with circular and 

 with other shaped tubes. Some attention has recently 

 been given to the question of D-shaped tubes, which are 

 being employed for the lower back fork of the rear-driven 

 bicycle. The object of making these tubes of D-section 



