Oct. 19, 1883.] 



KNOWLEDGE ♦ 



249 



wheels, and I hope a few remarks of mine may assist tricyclists in 

 forming correct conclusions. The reason why opinions so greatly 

 differ is that the height of the rider, the weight of the machine, the 

 gradient and surface of the road, and the comfort of the position 

 are not by different persons equally considered and allowed for. I 

 cannot give in a letter the mathematical proofs for my deductions, 

 but I will mention them as results only. It is a fact that 

 given the man and a perfectly level road, a machine can be 

 built to fit him properly, that is to say, on which he can exer- 

 cise the greatest comfort in position, the best average speed 

 suitable to his strength, and the best adjustment regarding 

 the transfer of his power to the machine, and with evenly-geared 

 wheels. This machine will be best for cycling on level roads with 

 ordinary obstructions. The dimensions of the wheels work out as 

 follows".— For a man 6 ft. high, 48J in. ; 5 ft. 10 in., 47i in. ; 

 5 ft. 8 in., 45J in.; 5 ft. 6 in., 44 in. Starting with this "best 

 machine," it is for cyclists to alter the proportions to suit their 

 various requirements. For racing on a level track the wheel can be 

 greatly reduced with much advantage from the saving of weight 

 and gearing-up. For rough level roads the reduction must be 

 much less than for racing.path — in fact, 2 in. less will be ample ; 

 .and for hilly roads a wheel 2 in. larger than the normal size will bo 

 more suitable, the gearing down or up being a matter of strength. 



The reasons that should guide a person in this matter are simple. 

 A big and little wheel run (for our purpose) equally freely on a 

 level surface without impediments. On a track, therefore, a 

 machine cannot in reason bo too light with small wheels geared-up 

 to the rider's power. Now, it is known that the measure of propul- 

 sion in a tricycle is the amount of weight in suspense in front of 

 the axles (that is to say, disregarding muscular propulsion, 

 which is only supplementary). When, therefore, a rider arrives 

 at a hill, the size of the wheel regulates the distance his weight 

 is thrown behind the axle, and as whatever weight is behind 

 the axle has to be compensated for by the propulsive 

 power before any propulsion is given to the machine, it necessarily 

 follows that small wheels are very much worse than large ones for 

 hill climbing, as the rider will have to uselessly expend exactly as 

 much force to counterbalance the amount of weight thrown behind 

 the axle, or else bend himself double. The larger the wheel, 

 therefore, the less waste on this account, so for rough roads and 

 hills it is better to have large wheels at the expense of extr.a 

 weight, which also gives increased strength, &c., for the extra 

 strains and jolts, the power being the same, owing to 

 the gearing-down. This principle being known, cyclists can then 

 choose small or large wheels according to the country they travel 

 in. I hope in my little work to explain the pros and cons that 

 should guide in forming an opinion as to the dimensions most suit- 

 able for special requirements. I would generally recommend a man 

 of ordinary power, with fairly good roads and content with from 7 

 to 8i miles an hour, weighing a fair average weight in accordance 

 with his height, to ride a machine evenly geared, with wheels 

 as in my table. Then if strong, and preferring a faster pace, 

 use larger or smaller wheels and gear up or down according to 

 the nature of the country generally ridden. For rough roads 

 err rather on the side of strength, as although a light 

 machine may be pleasant, still a feeling of safety against a pro- 

 bable collapse is to be considered, and I feel sure, for ordinary 

 riders, a machine built with evenly-geared wheels will afford the 

 gi'eatest pleasure for all-round work, and give most satisfaction. 

 I may mention that the swing frame enables smaller wheels to be 

 used for hill-work ; and as next season the patent will be open to 

 other makers, if they wish to adopt it, I have no doubt smaller 

 wheels will bo used in future, as the objection mentioned by me 

 before will be overcome by the rider's weight swinging in front of 

 the axle in accordance with the gradient. F. Warner Jones. 



LETTERS RECEIVED AND SHORT ANSWERS. 

 Omega. Thanks for corrections. But as to your remarks about 

 whist, tricycles, A'c, I would ask you to remember that there are 

 other readers besides yourself, who not only like these papers but 

 complain when (as recently) such articles do not a])pear regularly. 

 Your way of telling the editor what the generality of the readers 

 want is tant soi pen suggestive of coolness. — One who would like 

 TO BE Strong. Have sent your letter on. The author of these 

 articles says ho cannot think any ono can get harm from running 

 exercise begun and continued carefully as ho suggested. A pigeon- 

 breasted youth might certainly hurt himself by starting to run a 

 mile or even much less at the lirst effort. But a steady daily run, 

 begun at short distances and never pushed to distress, is not going 

 to hurt him, but rather to do him much good in the long run, even 

 if he should never come to a long run. — J. K. Mvrrav. Certainly 

 you are right. If you put the point of any object against a glass, 

 the distance between that point and its reflection will be twice 



the thickness of the glass, not once, as stated in "Reason 

 Why."— E. D. GiRDLESTONE. You insinuate that being editor I 

 burke your reasoning, and convert my editorial chair into a 

 " coward's castle." I can only follow the course which commends 

 itself to me as best, and it did not seem to me best to insert your 

 very long argument in defence of Jack Ketch, in the course of 

 which you made out that the average hangman is rather better 

 than military and naval men and might be (as you said at the 

 close) a long way better than the average editor. If it was very 

 ill-raannered, after that, to call your letter " illogical," or your 

 comparison between our fighting men and hangmen " sheer non- 

 sense," I am sorry ; but emphatically, my dear sir. You began it, as 

 boys say. You say you have learned to be pachydermatous: 

 verily, it is as well ; you need to be. Your picture of Jack 

 Ketch as " the ingenious mechanic inventing improvements in the 

 art of suspending and dropping weights and then putting his scheme 

 in practice," or as " the poorly paid father of a large family who 

 for his children's sake would accept work otherwise most distasteful 

 to him," may seem to you truthful. I hereby lay it before readers 

 of Knowleiige as the result of your thought over this subject; 

 merely remarking that the art of suspending and dropping weights 

 may be put in practice in other ways than by hanging, while I 

 should think a decent man with a large family would rather hang 

 ;i imself than degrade his children by taking the hangman's office. 

 In saying that everyone knows the real nature of candidates for 

 this office, I used a form of words which is I admit (will that 

 content you r) not strictly correct. One says in the same sort of 

 way. Everyone knows the earth is a globe, though of course strictly 

 speaking this is not true ; for there are a few who think the earth 

 flat, and I see now there is one Lieut. Middleton who has got beyond 

 that and thinks her surface rather hollow. As to your closing 

 remarks, I really have nevor thought whether I am "far your 

 superior in age and experience, in talent and acquirements." If 

 among my correspondents a Methuselah, with the experience of a 

 Solomon, the talent of a Galileo, and the acquirements of a 

 Whewell, were to advocate a view which seemed to me incorrect, 

 I should say so, and try to maintain the position I deemed just. For 

 yourself, if' in a half-column letter you can maintain your view 

 about the hangman, keeping to the question, and setting down 

 naught in malice about " the services " or my poor services as 

 editor here, you shall have the space. But what is mistaken for 

 editorial cowardice is very often editorial kindness. I get some 

 letters which it would be sheer cruelty to publish. — T. Harris. Too 

 bad of Airy to call them lunatics, was it not ? Yet not suitable 

 subject for a lecture. — Fatima. Quite with you on that question. 



Wr. Harri.*:. The sun rises at Hayward's Heath on November 



1st about 23 degrees south of east, or very nearly East-South-East. 

 Cosmos. Your question, "What is the rate of variation in the curva- 

 ture of an ellipse?" is not clear.— B. D. Thanks; but your sugges- 

 tion earlier ma^e by another.— E. K. II. A. Thanks for amusing 

 cutting from Tit-hits. It is news that the sun is ever at the zenith at 

 onr antipodes. The use of technical words probably made the 

 answer as good (or as worthless) as if it had been correct. — H. 

 Hansky. No room at present for Lithography. — Despondent. I 

 know of no better way to overcome extreme depression than by 

 getting something to occupy your mind and body too. Try s:>rae 

 long-lasting occupation for the Blue Devil as Michael Scott did for 

 his Black Ono. He set hini to make a rope of sand: you might try 

 to prove the earth a globe to the satisfaction of Mr. John Hampden ; 

 the task will be as endless, but it will serve the suggested purpose. 



T. R. HuTTON. That is probably the right view of meteoric 



and cometic matter; only there is not enough now left in our 

 system to be visible from any point of view as nebulous matter 

 round sun.— G. G. Chishot.m. Article in type, but great ]iressure of 

 matter mav prevent its early appearance. — C. H. Wren. A new 

 series of such notes will shortly begin.— .^.RNOLI) Reed. Please ask 

 questions separately.— W. Grandy. Thanks for suggestion.— 

 Silversmith. Thanks. Letter has already appeared.— Rerry Rix. 

 Ditto.— W. GiLDART. Do not know whore .\ndrews was born, or if 

 ho was really the originator of Moore's Almanac. — T. W. Piper. 

 Observations during last transit of Venus have not yet been 

 reduced. Thanks for suggestion about Knowledge ; wdl send to 

 publishers. Do not think the principles of spectrum analysis will 

 be affected if the new views about the luminosity of gas be 

 established. — Ursa Major. There is a full account _ of the 

 Lunar Hoax in my "Myths and Marvels of Astronomy."- J. T. 

 S. L. L. Why should those rays turn the earth ono way more 

 than another ? — Jas. Rowe. Explained in most recent books 

 of Astronomy.— .'Vmy Briggs. Your letter soon. Do not 

 myself know. — E. M. J. Thanks for encouraging letter. 

 —J. H. Thomson. Your letter unfortunately made such 

 travels to reach me, and was so long delayed, that it wonld 

 have been useless to send the enclosure on. They cannot have 

 been eggs though. 



