FOOTNOTES:
[4] In Russia the person having short sight is seated in a chair for several hours daily, with the head placed in a natural position for reading, but prevented from pressing forward. The page is at first placed at the short distance at which the eyes have been accustomed to observe; but this distance is gradually extended, until the humours of the eyes, constantly exercised in endeavouring to accommodate their powers to the gently increased demand upon them, at length acquire the capability of observing at the usual distance.
It is undoubtedly the fact that this character of sight may be acquired; many instances could be adduced of watchmakers and others, whose employments are of a sedentary or studious character, becoming short-sighted.
[5] It will be perceived that it is the workmanship and nice finish of the best town-made spectacle-frames which necessarily increases the price. Thus, a single pound of pig iron, which costs one penny, can be manufactured into watch-springs of the value of £240.