Wheel and Pinion.

71

Chap. 10.J

the rope on the small end of the fusee; and as tlie length diminishes, itcoils round the larger part. (See No. 20, which is however inaccurately

drawn_as the bücket is at the top of the well, it should have beeil repre-

sented as suspended from the large end of the fusee.) The value of a de-vice like this, will be appreciated when the great depth of some Wellsis considered, and the consequent additional weigbt of the chains. Inthe fortress of Dresden is a well, eighteen hundred feet deep ; at Span-genburgh one of sixty toises; at Homberg, one of eighty ; at August-burgh, is a well at which half an hour is required to raise the bücket;and at Nuremburgh another, sixteen hundred feet deep. In all these, thewater is raised by chains, and the weight of the last one is stated to beupwards of a ton: Misson, (vol. i, 116,) says three thousand pounds.

It is to be regretted that the name of the inventor of the fusee, and thedate of its origin, are alike unknown. It forms an essential part in the me-chanism of ordinary watches; for without it they would not be correctmeasurers of time. Every person knows that the moving power in aclock is a weight, and that the various movements are regulated by apendulum; but neither weights nor pendulums are suited to portableclocks, or watches ; hence a spiral spring is adopted as the first mover inthe latter, and when coiled up, as it is by the act of ‘ winding up’ a watch,the force which it exerts, imparts motion to the train of wheels ; but asthis force gradually diminishes as the spring unwinds, the velocity of thetrain would diminish also, if some mode of equalizing the effect of thisvarying force was not adojited : It is the fusee which does this, byreceiving the energy of the spring when at its maximum, on its smallerend; and as this energy diminishes, it acts on the larger parts, as on theends of levers, which lengthen in the same ratio as the force that movesthem is diminished.

No. 21. Windlass with cog wheel and pinion.

Iplf

In another modification of the windlass, a cog-wheel is fixed to one endofthe roller, and moved by a pinion that is secured on a separate shaft, andturned by a crank, as in the figure. By proportioning the diameter of thewheel and that of the pinion, (or the number of teeth on each) accordingto the power employed ; a bücket and its contents may be raised from