OF A NEW KIND OF
BARREL SPRING,
To lengthen the going of Clocks, Jacks, &c.
Although this invention does not properly constitute a new Spring, yet it produces effects both new and important. It protracts almost indefinitely the action of a barrel Spring, and thus reduces considerably the number of wheels in a clock or other spring-driven machine. This effect is produced by setting the two ends of the spring at variance; or making them act one against another: for as these opposite tendencies can be made nearly equal, one end of the spring will be wound up almost as much as the other end runs down: thus prolonging the effect in any desired proportion. It will be making known the principle, to describe the first motion of a clock founded upon it.
In [Plate 7], [fig. 1], A is the spring barrel, to which is fixed a wheel, B, of 96 teeth, working in C, a pinion of 17. E is another wheel of 92 teeth, working in F, a pinion of 22: both pinions being fixed on the same arbor, I G. The smaller wheel E, turns on a round part of the axis H D; and is connected with its motion in the backward direction only, by a ratchet wheel R, fixed on a square part of the same arbor. As usual, this latter has a cylindrical boss within the barrel A, to which the inner end of the spring is hooked; as its outer end is, to the rim of the barrel; and thus does the wheel B (when the clock is wound up) tend to turn forward as shewn by the arrow B; while the wheel E, tends to turn backward in the direction of E, the second arrow. But these opposite tendencies are not equal; because the wheel B is larger, and acts disadvantageously on C, the smallest pinion; while the wheel E is smaller, and acts to advantage on the larger pinion F: so that there is a decided tendency in the whole to turn backward. Now, to find precisely what is the effect of that tendency, we observe that when the barrel and the larger wheel B, have made one revolution round the common axis H D, the pinions C and F will both have made 96⁄17 of a revolution (being the quotient of the division of the wheel B by the pinion C:) and since the larger pinion of 22 teeth, works in the smaller wheel of 92 teeth; this latter wheel in the same time will have made 96⁄17 of 22⁄92 of a revolution, or 1,350 of a turn very nearly. The difference then between this quantity and unity, namely the decimal 0,350, is what the spring has really gone down during one turn of the barrel. And as the whole number of coils in the spring are 10, the number of turns of the barrel to uncoil it entirely, will be 10⁄0,350 or 10000⁄350 equal to 28,57 nearly: instead of ten revolutions which it would have been on the common principle.
It is almost superfluous to add that this prolongation of the time might have been greater, had I not been confined to the above numbers, for want of others more nearly alike, and having a common difference, on my engine.
An important remark here presents itself, viz. that the best properties of this invention are unattainable by the use of the common geering—the friction of whose teeth would have absorbed the small rotatory tendency thus retained; and in which system, also the working diameters of the wheels could not have been defined with sufficient exactitude. This then, is one of the cases in which (as I have observed in a former work) my late Patent System of Geering has “given rise to machines that could not have existed without it,”—which it does by possessing exclusively the property of realizing (sensibly) the whole calculated effect; and working without commotion or assignable friction. It may please some of my readers to be informed that this System, and the means of executing it in every dimension, will hold a prominent place in some future page of this essay.
Referring again to the [figure 1], the teeth X X, Y Y, are there placed to give a first idea of this principle: and they are unaccompanied by others, to avoid the confusion of lines that would have arisen from attempting to shew all the teeth, in their due position, on so small a scale. These things will claim all our attention when the System itself comes under examination.
The above representation of this Machine may leave a technical difficulty on the minds of clock makers relative to the winding up of this spring; which, in the present state of things, will suspend, for the time, it’s action on the pendulum: for in order to effect it, (in a reasonable number of turns) the introduction of the key must, by a proper check-piece, be made to stop the wheel B, and leave it again at liberty when the key is taken out: in which case ten turns of the key will effect the winding, although the Machine should be calculated to give out forty turns in the uncoiling of the spring. But if the wheels B and E had changed places; that is, if E had been fixed to the barrel A, and B been connected with the ratchet wheel R, then the act of winding up would have taken place in the opposite direction; or in that which tends to keep up the motion of the pendulum, in which case, however, the machinery of the clock must have borne the whole stress of the spring during the act of winding, instead of the small portion it sustains when the two ends counteract each other.