DESIGN FOR A VELOCIPEDE
Sir,—Expecting to be engaged in a situation, about three months ago, where there would necessarily be a great deal of travelling, and the income hardly sufficient to cover the expense of keeping a horse, over and above other expenditures, I applied myself to devise some method whereby I might travel with more ease and facility, than I could possibly do without some combination of art with nature. The following is the result of my cogitations, which I shall feel obliged by your submitting to your numerous readers, in order that any deficiency in the principle may be pointed out, for the benefit of mankind generally, and your servant humble in particular, as I intend to fit up such a machine, with the expectation of its being really useful.
A is one of two large light wheels, 8 feet in diameter, (which is the largest size, according to Professor Babbage, that can be rendered useful for such purposes) B is a guide-wheel, about 3 feet; C C is the body, or fixed frame of the carriage, made of wrought iron, and as light as possible: there may either be a seat for two persons, and a packing box or boot underneath; or, if designed for one traveller alone, it may merely be a platform case covered with loose oilcloth, to carry his food or any small article in. D D are the propellers, worked by the opposite cranks F, (on the same shaft,) and sliding freely P and down in self-adjusting guide-sockets, hung each on its own axis in the moveable frame E, which, when placed in the position most approved in practice, is held there by the screw at the lower part of said frame. G G are the treadles which work the cranks. The wheel B, with the crank propellers and adjusting frame, are all fixed in a straightforward direction on the spindle, which works freely in and passes through part of the frame C; consequently, the guiding is effected by a kind of side pressure, similar in effect to that of a person pushing a boat, when his hands are applied to some external object, as an abutment.
A few advantages expected to be derived from this arrangement, over any I have yet seen, I shall endeavour to point out; and any fallacy which may appear, or any improvement which may suggest itself to any of your ingenious readers, I shall feel pleasure in its being pointed out. I anticipate, when the speed is once attained, (which, on a good hard Macadamised road, will be readily done) it can be easily kept up by one complete stroke of the treadles to about four revolutions of the large wheels, which, being 24 feet in circumference, makes a clear distance of 32 yards, or about 7 smart strokes for every 200 yards. The operator continually rests on his right foot, which clears the propellers of the ground, and allows the guide-wheel to run freely if there ought to be a stout spring, or counterpoise by “dead weight,” for the purpose of carrying the crank over the upper centre, as connected with the right foot, for as he rests on that foot, it will need a help to start it. The cranks ought to be so adjusted with respect to each other, that just as the propeller is touching the ground, the man’s greatest force is operating on the crank (i. e. when it is at right angles with the treadles;), then the point of the propeller describes an elliptic, which will strike the ground more or less, according to the position of the sliding frame B, which lifts the wheel and fore-part of the vehicle off the ground, and drags the hinder part after U. Of course, the guide-wheel has already acquired a certain degree of motion, and therefore there is no check when it again reaches the ground.
I had almost forgot to remark, that there ought to be a circular spring “brake,” on which the operator might lay his right hand, and stop the carriage instantly, without any strain on the machine. The dotted lines on slide will show how I mean: when the traveller eases up his foot, the weight having power on the propeller the crank begins to act. With regard to the two machines described by Mr. Baddeley, I beg leave to state that I saw them tried fifteen years ago, in this town, by some good workmen, of the name of “Kilburn,” and either way (i. e. by using a handle or treadles to the cranks of the large wheels), they were such hard work that they were speedily laid aside. Another great benefit I anticipate from my arrangement is, that the hind wheels being disconnected, will make the machine turn with more facility, as the inner wheel can stand comparatively still, while the outer one works right round it.
I beg also to recommend the following modification of the above arrangement for steam-carriages on common roads, whereby the engines may be made of much less power, considerably lighter, and more effective. I am aware that Mr. Gurney and others have used propellers, but theirs have been placed, invariably, underneath the whole weight of the carriage and engine, thus constraining it to lift the whole of that weight in the circular part of the stroke. Now, I would propose that the engine, carriage, and load, should be all pretty nearly balanced on two wheels, (moving freely and independent of each other, as in an ordinary carriage) further, that the preponderance ought to lean on the third, or guide-wheel. The arrangement may be also such, as that the engine shall be always working slowly, only accumulating power at one part, and throwing it out briskly at that part of the stroke where it is most effective. The two propellers might, perhaps, be more efficiently placed by using two guide frames, one a little in advance of the other, so that when one propeller had lifted the fore-part of the carriage, and dragged it forward, the other one—its guide being more in advance—would give the whole a smart push, and so keep up or increase the velocity required.
In all the machines of this kind I have yet seen described, the traveller had harder to work, the quicker his pace; in this machine it is the reverse. I remain, Sir,
(The mechanics’ magazine, Vol. 36, 1842, pp. 152-3)