bolt, c, passing through the loops and the arms. The object of this is to make the crown part of the anchor stronger, to avoid the risk of breaking, which exists in those anchors united by scarfs.

The stock is constructed so as to consist of two pieces of timber or iron, which, when the anchor is not in use, may fold down as d, by means of a joint on each side of the shank; and, when required for use, these pieces may be extended as e, and secured in a cap or case of iron, so as to fasten them in their intended position. Various other modes may, however, be resorted to for the purpose of fixing the stock when used, which will readily occur to practical men, according to circumstances and convenience, depending in some cases on the size of the anchor.

A bolt passing through the iron case and the stock would be sufficient for small anchors; but in large ones, where the stock is of wood, a hoop and a wedge would answer better.

The iron stock, fig. 6, possesses the same advantages as those of wood; and the ends may be enlarged by wooden blocks, so as to prevent their sticking in the ground. This accident frequently happens in ordinary anchors, and prevents them from canting, from which circumstance the anchor is often rendered ineffective.

Inrolled, March, 1822.

To JAMES FERGUSON COLE, late of Hans Place, Chelsea, but now of Park Street, Grosvenor-square, London, for an Invention of certain Improvements in Chronometers.

THE first improvement proposed under this patent consists in the application of a safety pin to a detent

with pivots; a locking plate to the balance axis; and the return or unlocking spring in a reversed position, the escapement of the chronometer being a detached one. Plate V. fig. 1, shews the detent, a light bent bar, in the middle of which is an axis or pivot, a. On the upper surface of this bar a small stud, b, projects, which is acted upon by an angular notch, c, cut in the edge of a circular plate, d. This plate is attached by a screw, f, to the upper surface of the flanch or main pallet, e, or fitted friction tight on the pipe or neck. The flanch, or pallet, is firmly fixed on the balance axis, at g. The circular plate, d, is termed the locking plate, the outer edges of which extend a little beyond the extreme acting part of the main pellet, e.

At h, in the detent bar, the locking pallet is fixed, which retains the escape wheel during the excursion of the balance. When this pallet is adjusted to its properdepth in the escape wheel, the position of the safety pin, b, may be determined; as its place in the detent bar must be such as to allow freedom between itself, the extreme passage of the escape-wheel teeth, and the edge of the locking plate, d, on the balance wheel.

On the under side, and near the extremity of the detent bar, a stud, k, projects, into which the return or unlocking spring, l, is fixed. The depth which the lifting pallet, i, takes on the acting end of this spring is determined by its counter-pin in its acting end at 7, which pin rests against the nose, m, of the detent bar, and is shown by dots, because the locking plate and flanch would hide it. The end of the unlocking spring is hooked, and has motion nearly in a right line between the axis of the balance and the detent, which last-mentioned, with its appendages, must be accurately poised upon its pivot,

When the deep part of the notch, c, is in a position between the balance centre and the safety pin, b, the locking pallet, h, will be withdrawn from the repose tooth of the escape wheel by the lifting pallet, i, and the impellent-tooth of the escape wheel will be at liberty to fall on the acting part of the flanch or main pallet, e, to which the locking plate is attached. Both these are advanced together by the wheel's force, and before that impellent-tooth of the escape wheel has quitted the pallet, e, the locking pallet, h, will be again replaced and secured by the locking plate.

This method of locking is applicable to a wheel of the duplex kind, as shewn in the figure; and is also applicable to a wheel of the kind generally used in detached escapements; but, when the latter kind of escape wheel is used, the locking may be performed without the plate, d; as the angle for throwing the safety-pin, b, is, in that case, formed by the notch, c, which is cut in the edge of the flanch, e, forming the face or pallet against which the escape wheel acts in giving impulse.

The balance in this chronometer is constructed without arm, adjusting weights, screw, cavity, or projection, so that the atmospheric air cannot affect its circular movement. This balance is, in form, a circular plate, flat on one side, and on the opposite turned hollow, so as to leave no more substance than is absolutely necessary to support the rim.

The effect of heat and cold on this chronometer is compensated by a curb actuated by a compensator, the motion of which increases in one direction,and diminishes, in the other, the acting length of the balance spring. This curb and compensator are connected with the balance-cock and apparatus for adjustment in the following

On the upper surface of the balance-cock, at a, fig. 2, is fixed a turned collet, on the undercut neck of which is fitted, with a spring-clip, the moveable time-regulating piece, b, b. The shoulder of the collet, a, on which the time-regulating piece bears, projects as much above the upper surface of the balance cock as the thickness of the toothed rack attached to the under surface of b, and is acted upon by the tangent screw, c. This screw is supported by two cocks, d, d, secured to the foot of the balance-cock. Through the piece, b, b, is a long slit or groove, into which is fitted the tenon of the sliding nut, f. The compensator or expansion-piece, g, g, g, is of a circular form, (but this may be varied ;) the foot and outer part is of steel, the inner part of brass, the foot of which is firmly attached to the tenon of the sliding nut, f. On the upper surface of the sliding nut is the piece, h, having a hole tapped to receive the micrometer screw, i; in this is a turned groove, receiving the head of the guide, m, which is secured to the upper surface of the time-regulating piece, and prevents the micrometer screw from moving longitudinally.

By the revolution of the micrometer screw, the sliding nut, f, may be gradually moved along the groove, so as to regulate the rate of compensation necessary, according to the variations of heat and cold. On the circular part of b, two ears project, to which the bridge, n, is attached. Through this bridge, in a position nearly opposite to the centre of motion, an axis, p, is screwed; and on this axis, beneath the bridge, a moveable socket, g, is fitted. To this socket, the arm, r, and curb, s, is fixed. In the acting end of the compensator, g, is a stud, v, which forms a connection between the curb and compensator, by its action against the inner edge of the arm, r; which arm is kept in contact with the stud, v, by a spring,

(

w, fixed to the end of the compensator. The contact of the arm and stud is made by forming the piece, r, as a fork of two prongs, one of which operates as a spring against the stud, v, held between them. On the circular part of the arm, r, surrounding the socket, q, projects the time-regulating curb, s; on the under side of which are two pins, projecting for the purpose of checking the balance spring, which is held between them: x, is that part of the balance spring acted upon.

The operation of the regulator will now be seen. By turning the tangent screw, c, the regulating piece, compensator, curbs, index, and other parts, will be moved, and the acting length of the balance spring, thereby increased or diminished, according to the direction in which the tangent screw, c, is turned. The secondary curb, t, is fitted to the socket on the undercut edge; and on the step of this curb is screwed two pieces, %, %. In each of these is a small pin, (similar to those of the curb, s,) which admits of being moved separately nearer to, or farther from, the curb's centre of motion. These pins are intended to check the balance spring in the same manner as those of the curb, s; and their effects, when adjusted, are intended to compensate for the difference of proportion which the escape wheel's influence, and continuity of action bears to the long and short vibrations of the balance. Both the curbs, s and t, move in a circle corresponding to the curved form of the balance spring, x; whether actuated by the compensator or expansion piece, g, or by the motion of the tangent screw, c. To the extreme end of the arm, r, is fixed a needle, or index, pointing to the graduated scale.

Inrolled, March, 1821.