cate the teeth of two wheels, equal and similar in all respects, which are fixed upon the last arbor of the train; and the dark-shaded teeth marked by small letters belong to one of the said wheels; and the light-shaded or outline teeth marked by capital letters belong to the other of the said wheels, and are so placed, that, in the order of rotation, the points or extremities, of the teeth of one wheel do respectively stand in or near the middle of the interval between the points or extremities of ¿ the teeth of the other wheel; and the number and figure of the teeth to be made in the said equal and similar wheels may be such as the constructor shall think proper, according to the number of beats he may be desirous of producing in any given portion of time, and the nature of the material out of which he may think fit to make the wheels; or otherwise a single wheel may be used instead of two, and the teeth be made to stand contrate in the form of pins, or of any other suitable form, as in Fig. 2; or otherwise (but not by preference) a single wheel may be used. G and H are the working extremities of two pallets, of which the levers or arms terminate in distinct or separate axes or centres of motion; but the said axes are nevertheless so disposed, as to cause the motion of the said arms to be concentric with each other, and with the balance itself; or, in other words, the pallets and the balance do each move in different planes upon one and the same imaginary line or virtual axis. NN is the potence, or piece by which the pallets and the balance are supported. K and L represent back-springs, which urge the pallets towards the wheels (the said paklets being so placed in the potence, that one pallet shall apply itself to one wheel, and the other pallet to the other wheel respectively; or to the opposite sides and

faces

faces of a single wheel, if adopted in preference to two wheels as herein-before described); and to each lever there is opposed a stop, which prevents the pallet there. unto belonging from advancing so far as to touch the rim of its correspondent wheel. And the said back, springs may be respectively adjusted, with regard to their strength and action upon the said levers, by means of a screw applied to each, or by setting or bending, or by taking down the thickness thereof, as is well known to artists, and may by their action upon the balance altogether supply the place and office of the spring usually called the pendulum spring. And for the better obtaining and effecting this and other desirable purposes, a compensation for heat and cold may be applied in any of the usual methods unto the said springs, in case the same shall be preferred to a compensation on the balance itself; and the strength and action of the said springs may be regulated, and rendered more equable, in the several angular positions of the levers, by the interposition or use of a part or piece equivalent to the tumbler in a gun-lock, or to the jointed connection between the main-spring and a lever from the axis of the cock, as is sometimes done in the same instrument; both which, as is well known, do alter the action of the said mainspring, and might by a due proportion of the parts be applied (if needful) to equalize the same; and I do so proportion, and apply the said contrivances in some of my said improvements.

And I do make the face of each of my pallets to consist of an inclined plane, as seen in Fig. 1, or more distinctly at rt in Fig. 5, ending at t in a claw or detent, against which, in the detent H, Fig. 1, the tooth dis seen to rest, and prevent the wheel from running down;

and the said inclined planes are made to proceed in. wards from the levers towards the wheels or wheel, in the same direction as the said wheels or wheel when at liberty do move. And in order to insure the locking of the tooth upon the claw or detent, so as to prevent the possibility of any trip or disengagement of the wheel at an improper time, I do, when thought needful, make use of a banking-pin fixed to the arm of the inclined pallet, as seen in Fig. 6 at 7, which keeps the pallet from going farther back than is necessary to allow the tooth to raise up the pallet to its detent by means of the catch p, the end or joint of which is a very slender spring. And I do make or form a circular part standing out from the lever of the said catch, against which part the crank of the balance first acts, so as to remove the said catch out of the way of the banking-pin, until it has knocked out the detent, and set the wheel at liberty.

And lastly, I do make the verge or axis of my balance in the form of a crank, as in Fig. 4, in order that the vibration upon its pivots, concentric with the axes of the levers of the pallets, may be performed without any other interruption or action than is intended to be produced by the pallets themselves; and I do so place my balance, that the arm or extreme branch of the said crank shall lie or be disposed between the levers of the said pallets as at M. And the action of the said escapement, as delineated in Fig. 1, is as follows: the wheels being urged by the maintaining power to move in the direction marked by the small arrow at V, are prevented from revolving by the detent of one of the pallets (for example H), which holds against one of the teeth (for example d); but, as soon as the balance is by external motion made to vibrate, and its crank M comes to drive

back

back and displace the lever and pallet H, the wheels become disengaged, and move together, in consequence of which the tooth E, nearest the opposite pallet G, runs along the inclined plane of that pallet, and raises the same, until its detent being opposed to the tooth again stops the rotation; but during this process, the balance will have carried the other pallet H along with it in its semi-vibration on the opposite side, and will be followed by the same pallet in its return, through a longer arc than was employed in the divergence of the said pallet from the line of quiescence, because the said pallet will not in its said return be stopped upon the extremity of a tooth, but will proceed into the space be-tween the teeth d and c, until it nearly touches the rim of the wheel (being prevented from actual contact by its stop). And as soon as the balance returns to perform its semi-vibration on the side of the pallet G, last raised up by its wheel, it will carry away that pallet, and in like manner disengage the wheels; by the rotation of which, the other pallet H will be again raised. And the alternations will be repeated without limit so long as the motion of the wheels is kept up, because the reaction of the back-springs K and L will be greater in the return of the balance to its first position, than in the other parts of each vibration.

And I do further declare, that my said improvements are capable of being varied, disposed, and applied in and to the construction of watches and chronometers in several different manners, which will readily and without farther instruction be deduced froin the preceding descriptions and drawings, by any workman of competent skill in works of this or the like nature; and in particular that the pallets may be both placed on the same

side

side of the wheels or wheel, and the balance may raise them, and receive their maintaining re-action, by means of pallets proceeding from a strait verge, as is shewn in Fig. 3, where the same letters denote the same things, as in Fig. 1, excepting that the letter M shews the pallets of the verge, which in this case is not concentric with the axes of the levers, and upon that and other accounts I do not consider it as being entitled to preference. And farther, that the same materials, workmanship, compensations for temperature in the balance or elsewhere, and other expedients and contrivances for insuring the durability and truth of performance, as are well known and used, and applied in the best chronometers of other constructions, may be also used and applied with and to chronometers, in which my said improvements herein-before set forth and explained shall be adopted and introduced, provided that attention be paid to the nature and intention thereof.

or may

And I do farther declare, that I do improve watches and chronometers by stopping the holes with platina, instead of using hard brass or jewelling in movements or the parts thereof wherein my said improvement of stopping with platina may be preferred or required. In witness whereof, &c.

Specification