March 20, 1884] 



NATURE 



479 



measured terms the evils likely to result from the develop- 

 ment of this new craze, in which, as far as I remember, it 

 was stated that we are now sowing the seeds of a series of 

 new diseases, the symptoms of which will only appear 

 possibly in years to come. I would not for a moment 

 question the accuracy of opinion held by any professional 

 man ; whether this is or is not the case 1 cannot tell ; 

 however, I may mention that the only s>mptoms which I 

 have so far discovered in myself are an improved appetite, 

 increased weight, and a general robustness to which I 

 was formerly a perfect stranger. Having, I trust, suc- 

 ceeded in showing that the advantages offered to riders 

 are sufficient to account for the rapid development of 

 cycling, that it is in fact no mere temporary craze, I shall 

 now proceed to consider the theory and construction of 

 the various machines at present known. 



From the hobby horse to the bone-shaker, and from 

 the bone-shaker to the bicycle, the steps are so simple 

 and obvious that it is quite unnecessary for me to trace 

 them. It is also needless for me to describe the modern 

 bicycle : every one must be familiar with it, every one must 

 have seen the ridiculous zigzag of the beginner, and have 

 admired the graceful gliding of an accomplished rider. 

 Of the theory of the balance little need be said ; any- 

 thing supported in a mere line, in unstable equilibrium 

 as it is called, must fall one way or the other. The 

 machine and rider would of necessity capsize if some 

 action of recovery were not possible. To whichever side 

 the machine shows any inclination, to that side the rider 

 instinctively directs it. By this means the tendency to 

 fall to one side is balanced by the property of the rider to 

 continue moving in a straight line, and so to go over on 

 the other side. This action of recovery is always over- 

 done, so that a second turn in the opposite direction must 

 follow. Hence the extraordinary path traced by the 

 beginner. Even with the most skilful rider, though he 

 appears to travel in a perfectly straight line, a slightly 

 sinuous course is essential, as the highly characteristic 

 track left on the road indicates. If anything should happen 

 to check this slightly serpentine motion, as, for instance, 

 occurs when the driving-wheel drops in the groove of a 

 tram-line, the balance at once becomes impossible, and 

 the rider is compelled to dismount. 



The extraordinary stabiliiy of the bicycle at a high 

 speed depends largely on the gyroscopic action of ihe 

 wheels. On the table is a top supported in a ring which 

 is free to move how it please?. So long as the top is 

 spinning the ring is as rigid as a block ; on stopping it, 

 the freedom of the support- is at once apparent. 



It is a marvel to many how anything so light, how any- 

 thing so delicate, can carry the weight or can travel at 

 the speed so common without utterly collapsing. The 

 wheels especially attract attention. In a hoop no one 

 part can be pushed in unless some other part can go out. 

 A bicycle wheel is a hoop in which every part is prevented 

 from going out by the tension of the spokes. To give 

 the wheel lateral stabiUty, the spokes are carried not to 

 the centre, but to the two ends of the hub, thus lying on 

 two cones. Such a wheel is abundantly strong in its awn 

 plane : it can withstand the jars and shocks of a bad road 

 without a groan, but once subject it to serious side strain, 

 such as I can with ease put upon it with a jerk of my 

 wrists, and the wheel will crumple up like an umbrella in 

 a storm. Till this \ear there has been no change in the 

 principle of construction, though in detail many improve- 

 ments have been carried out and are largely adopted. By 

 the use of hollow rims a stififer and lighter wheel can be 

 made ; thick-ended, crossed and laced spokes are em- 

 ployed, and other details modified. Essentially, however, 

 the "spider" wheel as a structure is the same as it was 

 when first introduced. Suddenly two radical changes 

 are presented to us. Mr. Otto, whose great work I shall 

 describe in its proper place, has devised a wheel on a new 

 system, in which the spokes that form the structure lie in 



the plane of the rim, in which position they are best able 

 to withstand direct shocks. Such a wheel would be un- 

 stable, but requires very little to keep it true. Delicate 

 spokes, not screwed up very tight, are therefore placed on 

 either side, so that a side-strain is met by the whole 

 strength of the spokes on one side, which are not as 

 hitherto weakened by the pull of the spokes on the other. 

 On this system much narrower wheels can be made than 

 was possible before. The other change, due to the same 

 inventor, is still more striking. He has found, contrary 

 to the opinion of every one, that wheels, either of hi^ 

 narrow type or of the usual form, can be made and will 

 remain true when the spokes are made elastic by being 

 bent into a wavy or slightly spiral form. If only these 

 wheels will stand the test of time — and I see no reason 

 why they should not — one of the greatest discomforts and 

 possible causes of injury from which the cyclist suffers— 

 the vibration and jolting due to a bad road — will have been 

 removed. 



The bearings in a bicycle are perhaps more to 

 be admired than any single part. Instead of allowing 

 the axle to slide round in its bearings, hard steel rollers 

 or balls are introduced, so that the parts which are pressed 

 together roll over and do not slide upon one another. 

 Any one who has trodden on a roller or a marble must 

 have found in a possibly unpleasant manner the great 

 difference between rolling and sliding friction. I can 

 now give for the first time the result of an experiment 

 only completed this morning, which shows the extraor- 

 dinary perfection to which this class of work has attained. 

 I have observed how much a new set of balls which 1 

 obtained direct from the w-ell-known maker, Mr. Bown, 

 has lost in weight in travelling icoo miles in my machine. 

 Every 200 miles I cleaned and weighed the balls with all 

 the care and accuracy that the resources of a physical 

 laboratory will permit. The set of twelve, when new, 

 weighed 2 5 '80400 grm. After 1000 miles, they weighed 

 25'8ooS8 grm., the loss being 3'i2 mgrm., which is equal 

 to i/20'8 grain, that is, in running 1000 miles, each ball 

 lost 1/250 grain. This corresponds to a wear of only 

 1/158,000 inch off the surface. At this rate of wear — 

 3"i2 mgrm. per 1000 miles — the balls would lose only 

 i/34'3 of their weight in travelling as far as from here 

 to the moon. 



The twelve balls, after the first 200 miles, each weighed 

 in grammes as follows. The loss of each in running 60c 

 miles is appended : — 



I did not weigh each ball on the first and last occasion. 

 However, the wonderfully uniform wear in the interme- 

 diate 600 miles speaks well for the equal hardness of the 

 balls. 



The wear of the dozen during each journey of 200 

 miles was as follows : — 



M.les 



o — 200 



200 — 400 



400- 600 



600 — 800 



800 — ICOO 



-C0055 

 -00070 



-OC055 



-00075 

 -00062 



I have" given the results of these experiments at length, 

 for I do not think that accurate and systematic observa- 

 tions of the kind have been made before. 



We may consider, then, that the balls are practically 

 indestructible. Knowing this, Mr. Trigwell has applied 

 the ball-bearing to the construction of the " head " of the 

 bicycle, not so much with the view of diminishing the 



