When this method is applied to a clock or watch fusee, there is a circular and flat steel spring screwed or made fast by one end to the inside of the great wheel ; in the other end is a small hole, opposite to which is made a short and circular slit in the great wheel. A pin in the auxiliary ratchet is placed so as to correspond to the hole in the spring and the slit in the great wheel, through both of which it comes ; the slit gives range for the bending up of the spring. When the force of the main spring does not act on the fusee, which is taken off when winding up, the auxiliary ratchet and detent, which has a slender spring to keep it to its place, sRrve the same end as has been de scribed for the clock.
The mechanism of this going in time of winding, was first exhibited by Harrison in his timekeeper, when ex plaining its principles to the commissioners who were ap pointed to receive them. It has been said that lie took the idea of it from having seen an analogous contrivance in an old kitchen jack, where it had been applied to keep the spit turning while the jack was winding up. There has been a great deal of ingenuity displayed even in jack-making.
It is singular, however, that it was never thought of to ap ply vanes or wings to the fly, which could have been set so as to regulate the velocity according to the greater or less weight with which the spit might be loaded ; but, simple as the setting of these wings would be, it might not be so easy to prevail upon the cook to take the trouble of either no derstanding or using them. The water-jack, which has been known in this country for more than seventy years, is very convenient in this respect, as it is so easy to make the discharge of water at the cock to run full, half, or quarter, on the small kind of mill-wheel which drives the whole of the machinery belonging to the jack.
A great many years ago, we contrived an easy way of making a going in time of winding for a clock, to several of which it was applied. The third wheel has a socket (with a small shoulder) truly fitted to it, the hole being soundly and smoothly broached. That part of the third wheel pinion arbor, which works in the socket, must also be truly turned, and made as smooth as any pivot, so as to be free, easy, and without shake. The end of the socket, which is not in the wheel, should be smooth and flat ; its diameter outside about three-tenths of an inch, and to ap ply to a flat smooth steel shoulder formed on the pinion ar bor. On the side of the wheel opposite that on which the socket shoulder is placed, let there be fixed a small.steel pin, distant from the centre about three-tenths of an inch, the height of it being about one-tenth. Nlake a piece of brass so as to have a fine small ratchet wheel on it, of about four-tenths of an inch in diameter, with a sort of hoop or contrate wheel rim on one side of it, three-tenths and a half in diameter inside, the thickness being a little more than that of an ordinary contrate wheel of a watch, and the depth one-twentieth of an inch. Vie ratchet wheel and hoop have a socket common to both, which is twisted on the third wheel pinion arbor ; this socket on that side of the hoop in side, is the smallest matter lower than the edge of the hoop ; on this part of the socket is fixed the inner end of a small and weak spiral spring, of two or three turns, the outer end having fixed to it a small stud, with a hole in it, that goes over on the steel pin of the third wheel, which works in a short circular opening in the ratchet wheel or bottom of the hoop, of a sufficient range for the spiral spring to keep the clock going during the time of winding up.
The detent for the ratchet has one of the pivots of its arbor in the back frame plate, the other runs in a small cock at tached to the inside of this frame plate, and sufficiently clear of the third wheel on that side. The edge of the hoop, when the socket is twisted home, should allow the third wheel to have freedom during the action of the spiral spring on it. In applying this going in time of winding apparatus to a clock, it will easily be seen in which way the small ratchet teeth must be cut, and also in which way the spiral spring must exert itself. During the action of winding up, this allows the minute hand to make a retrograde motion, but it resumes its place as soon as the weight is at liberty.
In the early part of the last century, a considerable in tercourse was carried on between Holland and Port Seaton, by the ship owners of Prestonpans, in East Lothian. Among the imports, was old iron in hogsheads, and many of the articles were little worse for being used, as, by a law with the Dutch, no iron work was allowed to be repaired. Among the things which came home were some camp jacks, of a very ingenious construction, and evidently of German origin. Two or three of them, one of which we have seen, are still in that neighbourhood. It was corn posed of the usual wheels and pinions, endless screw, and a small fly, rather weighty. The frame mounted on an upright stand, was about four feet or more in height. A thin and narrow iron bar, of four or five feet long, was at tached to the stand, and could be made to slide up and down on it, nearly the whole lour or five feet ; One edge of it was toothed like a straight rack, and worked into the pillion of the first wheel, by means of a weight or weights hung on a hook at the lower end of the bar ; when the weight and bar came to the lowest point, it was easily moved up to the greatest height, when the jack was to be wound up. The pinion had a hollow socket, and could turn freely round the arbor of the first wheel ; on the lower end of the socket was a ratchet which rested on the first wheel, where the click and spring was placed to act with the ratchet, which by the hollow socket allowed the pinion to turn freely backward when winding up ; on the weight be ing allowed to act on the rack, all the wheels were made to tut n the proper way, and so on. An idea occurred to us, that, in place of the rack moving, a machine might be made to go by its own weight, by means of a pinion turning down on the toothed edge of a fixed rack. A scheme shall be given for a box chronometer of this construction, which su pCrsedes the necessity of either fusee, barrel, spring, or chain. A contrivance of a similar kind has lately been communicated to the Society of Arts in Paris, by NI. Isa belle, and is described in the Bulletin de la Societe d'En couragcmcnt, No. 52. The same method, which has been known for a considerable time, is used at Liege by Hubert Saxton, who makes eight day spring clocks on this plan.