The Full Plate Patent English Lever.
Three-Quarter Plate English Lever.
From the time when the first Nuremberg egg-watch was produced, there has always been noticeable an endeavour to make pocket time-pieces more and more small and portable so far as they could be made so consistently with their durability. Sometimes the love of very minute workmanship has been carried to an extreme, but toy-watches of eccentric shapes and patterns are but the few exceptions to the general rule, which has settled that usefulness and convenience are best provided for within certain moderate sizes, and that of all shapes the round and flat are the most easily carried. The great object of the watch-maker's ambition is to produce a time-keeper minutely accurate, and yet not so delicately constructed that it cannot withstand the rough usage to which even moderately careful wearers subject it.
It has been estimated that the manufacture of and trade in watches annually in England, France, Switzerland, and America, amount to over £5,000,000 per ann.; and that in Switzerland alone there are 38,000 persons, one-third of whom are women, engaged in the manufacture. It is probable that even the immense number of new watches thus annually produced barely exceeds the growing requirements of the people, who, as they increase in intelligence and receive higher wages, soon learn the advantage of personally possessing a pocket time-keeper, and make it accordingly their first ambition to purchase one. The Watch Clubs which are formed in the various towns and rural districts throughout the kingdom enable this desire to be gratified at but small pecuniary inconvenience, inasmuch as payment is thus made in small instalments at fixed intervals, and the watch is bought with sums which might have been spent thoughtlessly and to no permanent benefit. This first lesson in thrift having been well learnt, and the result being so palpably beneficial to those who exercise it, has often laid the basis of a regular habit of economy.
The motive power in the watch is derived, not as in the clock from weights, but from a spiral spring called The Mainspring, set in a drum or barrel, and any inequality in the pressure of the spring is fatal to regular time-keeping. A highly tempered and finished spring is a primary requisite in watch-making; in order to provide for the uniform transmission of motive power from the barrel throughout the train to the escapement, the fusee and chain are used, the fusee being a hollow-sided cone, and the chain round it. When the spring is wound up its force is of course greatest, for the chain is then acting on the smallest end of the fusee. The proportions of the barrel to the centre wheel, and the size of the teeth in that wheel, have all to be carefully planned, and adjusted to one another, and these all again to the moving of the hands upon the dial.
The Escapement is one of the most important parts of the mechanism of a watch. It may be one of either of the following.
Verge Escapement.