That the vision is more natural and perfect when both eyes are employed than when one glass only is used, must be self-evident, as the axis of each glass, placed as they should be in the spectacles, coincides with the axis of each eye, and the rays of light are thus equally refracted to the eye. Again, the eyes have a most acute and sensitive sympathy with each other, and when a single eye-glass is constantly used they are unnaturally exercised, and prevented from acting in concert. One eye (generally the right eye) has the glass perpetually applied to it; and very frequently, in consequence of this pernicious practice, becomes of a different focus to the other. Mr. George Adams informs us that he did not recollect an instance of a short-sighted person who had occasion to increase the focus of his concaves if he began by wearing spectacles, but that the cases were frequent, where a single eye-glass had been used, in which the persons had frequently required a change of glasses. The prices of spectacles are diversified and fluctuating, like all other manufactures, so that to publish a list of prices would only tend to mislead and deceive my readers. For instance, the price of a pair of pebbles, used formerly to be one guinea extra to the charge for glasses; they are now reduced to half that sum. A pair of pebbles, of the concave or of the periscopic figure, were at the same time charged twenty-five shillings. These have been reduced in the same proportion. And it cannot be too universally known, that a person can have a pair of good convex glasses fitted into his spectacles, and correctly suited to his sight, at from one shilling and sixpence to two shillings per pair, by any respectable optician. The poorest person may be defended against the tender mercies of the spectacle speculators; for he really can obtain a better article for his money, both in quality and suitableness to his sight, of the respectable optician, and, upon an average, at _a less cost_ than the cheat contrives, by dint of manœuvring, to extract from him. Good lenses, in plain frames, or, in other words, a good pair of spectacles, may be had, correctly suited to the sight, for two shillings and sixpence. Who then, knowing this, would suffer his sight to be tampered with? Truly, those who would stickle for a shilling in the price of such valuable and essential instruments “Deserve not the comfort they shed o’er the soul.” Yet, at the same time, there is no reason why those exorbitant charges should be submitted to, which are often paid without hesitation by the delighted purchaser, when a pair of spectacles appears to suit his sight.