22 Mr. a Vernon Boys [March 7, 



applied to the cranks is transmitted to a differential gear by a chain. 

 The crank and connecting rod have also been used to transmit the 

 power, but then the clutch is necessary. 



There is, however, another type of tricycle in which the use of 

 cranks is avoided, among which may be mentioned the " Omnicycle," 

 the " Merlin," and that highly ingenious machine the " Oarsman " 

 tricycle. On the table there is the Omnicycle gear. In all these 

 the power is applied direct to the circumference of a wheel or sector, 

 and so dead points are avoided, which is a point in their favour when 

 meeting with much resistance. On the other hand, the sudden starting 

 and stopping of the feet at every stroke in the two former machines 

 and of the body in the latter makes this type utterly unsuitable for 

 obtaining anything more than a moderate speed. In the Omnicycle 

 ingenious expanding drums are employed so that the power may be 

 applied with different degrees of leverage according to circumstances. 



There remains one type of tricycle which for rapid running sur- 

 passes many : I refer to what is known as the Humber pattern. So 

 excellent is this form in this respect that the leading manufacturers 

 have, by turning out machines on the same lines, paid the original 

 makers a compliment which is not altogether appreciated. This 

 pattern departs less from the ordinary bicycle than any other ; it is 

 one, in fact, in which, instead of one, there are two great wheels, giving 

 width to the machine, between which the power is divided by the 

 usual differential gear. 



I must now describe some devices which are attracting much 

 attention at the present time, the speed and power gears. Let us 

 suppose there are two machines with wheels of different sizes, but in 

 other respects alike. Then each turn will take the larger-wheeled 

 machine further than the smaller. In going up a hill the larger 

 wheel will take its machine up a greater height than the other in one 

 revolution, which involves more work and therefore more strength. 

 If on the large wheel the chain pulley were increased in size, then 

 for the same speed of the treadles it would not turn so quickly : it 

 would not take the machine so far up the hill as before : it would, in 

 fact, be equivalent to a smaller wheel, so that less strength than before 

 would be necessary. This diminution of speed, though of great 

 advantage when climbing a hill, is the reverse on the level, for there 

 very rapid pedalling would be necessary to maintain even a moderate 

 speed. To obtain the advantage of high wheels or high gearing on 

 the level, and at the same time low wheels or low gearing on the 

 hills, some highly ingenious devices are employed. On the table is 

 a well-known example, the " Crypto-dynamic," which by a simple 

 movement changes the relative speed of wheel and treadle. Time 

 will not permit me to describe the details of this arrangement, but it 

 contains an epicyclic gear, which is or is not in action, according as 

 the rider desires power or speed. There are several other devices 

 having the same object, some depending on an epicyclic gear in a 

 pulley, others on the use of two chains, only one of which is active at 



