381. Robert Southey to the Editor of the Monthly Magazine, 21 February  *
Perhaps the following method of assisting a weak sight may not be commonly known. I translate it from La Nouvelle Bigarure for February 1754.
“The author of this discovery was about sixty years of age; he had almost entirely lost his sight, seeing nothing but a kind of thick mist, with little black specks which appeared to float in the air. He knew not any of his friends, he could not even distinguish a man from a woman, nor could he walk in the streets without being led. Glasses were of no use to him; the best print, seen through the best spectacles, seemed to him like a daubed paper. Wearied with this melancholy state, he thought of the following expedient.
“He procured some spectacles with very large rings, and taking out the glasses substituted in each circle a conic tube of black Spanish copper. Looking through the large end of the cone he could read the smallest print placed at its other extremity. These tubes were of different lengths, and the openings at the end were also of different sizes; the smaller the aperture the better could he distinguish the smallest letters; the larger the aperture the more words or lines it commanded, and consequently the less occasion was there for moving the head and the hand in reading. Sometimes he used one eye, sometimes the other, alternately relieving each, for the rays of the two eyes could not unite upon the same object when thus separated by two opaque tubes. The thinner these tubes, the less troublesome are they. They must be totally blackened within so as to prevent all shining, and they should be made to lengthen or contract, and enlarge or reduce the aperture at pleasure.
“When he placed convex glasses in these tubes, the letters indeed appeared larger, but not so clear and distinct as through the empty tube: he also found the tubes more convenient when not fixed in the spectacle-rings; for when they hung loosely they could be raised or lowered with the hand, and one or both might be used as occasion required.” 
Bristol , February 21.