TRICYCLE. Though velocipedes were made and used more than one hundred years ago, none were practically successful until the brothers Starley constructed in 1876 the Coventry tricycle. One of the earliest descriptions of a cycle occurs in the Journal de Paris of 17th July 1779. Somewhat later M. Richard invented a machine driven by mechanism almost identical with that of the modern omnicycle, but without the expanding segments. Early in the 19th century the cranked axle worked by treadles and levers came into fashion; then the heavy four-wheelers were preferred. All these machines, how-ever, laboured under three fatal defects: it was almost impossible to drive them up-hill, to check them in going down-hill, and to prevent their overturning in rounding a corner.
It was the success of the early bicycle (see BICYCLE) which suggested the belief that a serviceable tricycle could be made. One of these bicycles was specially constructed for ladies, the hind wheel being placed well on one side; but, though it could be ridden, it was not a commercial success. The brothers Starley, by putting a second small wheel in front of the large driving wheel and on the same side as the small hind wheel, gave stability to the machine;
it was steered by turning the small wheels opposite ways, and driven by the large wheel by means of cranks and connecting rods. The same machine with chain driving —the Coventry rotary—is still very largely used. In 1877 James Starley, it is believed without any knowledge of the gear used by Fowler for traction engines, re-in-vented the same differential gear for tricycles. By this the same force is, under all circumstances, applied to each of two equal driving wheels, and the evil effects of driving a single wheel are done away with. This gear was used in the original Salvo tricycle, which is the type of the surest machine at the present day. In the early days of the modern tricycle other designs were carried out, which have now become practically obsolete. In one form the hind wheel of a bicycle was replaced by a pair of equal wheels, one on each side, but the instability of such a construction was fatal. In another, the Challenge, the two wheels were placed in front of the large driver and turned together to steer the machine; stability was ob-tained by putting the rider in front of the large wheel and lower down, the power being communicated by cranks and connecting rods. But the weight of this machine and the small proportion of the load on the driving wheel were serious defects.
Single-driving rear-steerers were at this time very common, and, though highly objectionable, are still to be seen. Rear-steerers were improved by making both front wheels drivers and allowing for the overrunning of one or the other by clutch, as in the Cheylesmore, or by ratchet driv-ing ; but steering by the hind wheel is essentially wrong, and these machines are avoided by experienced riders. Rear-steerers have, however, lately been made with a through axle and differential gear (Rover), the rider being placed further back so as to increase the load on the steering wheel; but the evil of rear-steering is only re-duced, not removed. The clutch is also employed on some front-steerers; and, though in certain respects it has an advantage over the differential gear, for general use it is not so suitable. The differential gear is an essential feature of the modern tricycle.
In 1878 Messrs Doubleday and Humber patented the Humber machine, which is both driven and steered by the two front wheels, the rider being seated on a trailing backbone and hind wheel as in the bicycle. This machine requires skill to manage : the steering is at first difficult to control and a spill over the handles is quite possible; under a skilful rider, however, the Humber is generally recognized as one of the fastest machines. It is steered by a cross handle, like the bicycle, and this method of steering, in spite of the fact that it boxes the rider into the machine, is becoming very general in front steerers in place of the rack and pinion steering hitherto in use. The Cripper is a very popular example. The brake is an im-portant feature in roadster tricycles. It is always made to act on the box of the differential gear where that is used; but in clutch or single-driven machines one or two independent band-brakes or spoon-brakes are used.
In early days the steering wheel was made small to save weight; the drivers were often 50 inches or more in diameter; and the machine was as short as possible. Owing to the discomfort attending a small wheel and a short base the tendency at present is to increase the size of the steering wheel and the length of the base, and to diminish the diameter of the drivers,—two notable examples being the Quadrant and the Crescent. It is usual, especially when small driving wheels are used, to gear the machine up, just as in the old days they were commonly geared down; that is, the chain wheel on the crank axle has more or fewer teeth than that on the wheel axle, and thus the wheels turn faster or slower than the

cranks, or are equivalent to larger or smaller wheels. Two-speed gears are becoming general, among which may be especially mentioned the Cryptodynamic. By means of these it is possible to change the gear of the machine so as to have a high gear under favourable conditions and a low gear when mud, wind, or an ascent make travelling difficult. Although chain gearing is used in nearly every machine made, connecting rods, wheels, or bands are fitted instead to some machines. The necessity for such mechan-ism has been avoided by making the wheel axle also the treadle axle; but great instability is the result.
Machines in which the arms instead of the legs supply the power are made, ana are of immense service to those who have lost the use of their legs.
Owing to the inconvenience caused by doorways being often too narrow to allow a tricycle to pass through, many machines are made to fold up into a narrower space or to shut up like a telescope.
It is important that the rider should be so placed that he can, without leaning forward, put most of his weight on the treadles, and this is more than ever needed as the steepness of an ascent in-creases, because the slope of the machine has a contrary effect. Slid-ing seats were arranged for this purpose; but Mr Warner Jones has made use of a swinging frame which the rider can lock in any posi-tion he pleases. It is this same swinging frame which gives such comfort to the rider of the Otto bicycle, placing him at all times in the position most suitable for the occasion.
Carrier tricycles, in which due provision is made for the proper distribution of the load, are largely used by the post-office and by tradesmen in their business. The " Coventry chair " is a kind of bath chair driven as a tricycle by a rider behind. When invalids have overcome a certain prejudice as to the danger of this kind of vehicle, it will no doubt be more generally used.
In machines for two riders the riders sit side by side [sociables) or one is placed before the other [tandems). Sociable machines are both front-steering and rear-steering. Kear-steerers with each rider driving the wheel on his side only are nearly as objectionable as the single-driving rear-steerer. Front-steering sociables with dif-ferential gear are safe and comfortable ; but all sociables are slow machines. For nearly every make of single tricycle there is a corresponding tandem. The Coventry rotary in the tandem form suffers more from the single-side driving than in the single form, the rear-steering machines not so much, owing to the greater weight which the steering wheel has to bear. The Humber is less sen-sitive in the steering, owing to the greater moment of inertia of the frame and the front rider. The front-steerer cannot be made safer, but an excellent tandem is formed by placing the rear-rider on a trailing tail as in the Humber. Tandems have an advantage over sociables and perhaps over single tricycles in the matter of speed ; they are, however, not quite so safe, and their appearance alone prevents many from riding them. Many sociables and tandems are convertible into single machines with but little trouble.
The following tables of quickest times which have been accomplished up to the end of 18S6 (certified by the National Cyclists' Union) will show the com-parative value of the bicycle and tricycle as racing machines.
On a prepared racing path.

== TABLE

Greatest distance in one hour { fQ ln»es «°Q ^
On a public road.
Land's End to John o' Groats j 5 days 10 hrs., tricycle.
(about 870 miles) 1 5 ,, 1 45 min., bicycle.
Greatest distance in 24 hours I g£* miles' tricycle.
( 295 „ bicycle. (C. V. B.)