But we stop not here. The part p q of this [figure], shews a pair of wheels doubly inclined—one of them only, being made in two halves, which are connected together by screws and washers, like that just described. Here then, another degree of friction is got rid of—namely, that of the cheek o: but still, a small degree remains, (dependent on the double versed sine of the angle formed on the wheel’s circumference, by the thickness of a tooth). This quantity, is indeed, very minute; and brings, perhaps, the whole near enough to perfection. To do, however, completely away with all friction, (see my preceding statement)—as well in the wheel acting backward, as in that acting forward, we must do what is shewn in the parts r or s of [fig. 4]: we must have a pair of V wheels on the same shaft, with the power of turning one of them in reference to the other; and then connecting them by proper screws, &c. to preserve the position thus given: by which means, in a word, all shake or backlash will be completely annulled.
PART FIFTH.
A NEW CENTURY OF
Inventions.
OF
AN ADDING MACHINE,
Or Machine to Cast up large Columns of Figures.
This Machine is not, generally, an arithmetical Machine. It points lower: and therefore promises more general utility. Though less comprehensive than machines which perform all the rules of arithmetic, it is thought capable of taking a prominent place in the counting-house, and there of effecting two useful purposes—to secure correctness; and thus, in many cases, to banish contention. It is represented in [figs. 1], [2], [3, and 4] of [Plate 42], and in [figs. 3 and 4] of [Plate 43].