With the object-glass of a common refracting telescope 4-1/2 feet focal distance, and 2-1/2 inches diameter, I looked at distant objects--my eye being at about 3-1/2 feet from the lens, or about 10 or 12 inches within its focus--and it produced nearly the same effect as a telescope which magnifies the diameters of objects 5 or 6 times. With another lens 11 feet focal distance and 4 inches diameter--standing from it at the distance of about 10 feet, I obtain a magnifying power of about 12 or 14 times, which enables me to read the letters on the sign-posts of a village half a mile distant. Having some time ago procured a very large lens 26 feet focal distance, and 11-1/2 inches diameter, I have tried with it various experiments of this kind upon different objects. Standing at the distance of about 25 feet from it, I can see distant objects through it magnified about 26 times in diameter, and consequently 676 times in surface, and remarkably clear and distinct, so that I can distinguish the hour and minute hands of a public clock in a village two miles distant. This single lens, therefore answers the purpose of an ordinary telescope with a power of 26 times. In making such experiments our eye must always be _within_ the focus of the lens, at least 8 or 10 inches. The object will, indeed, be seen at any distance from the glass within this limit; but the magnifying power is diminished in proportion as we approach nearer to the glass. Different eyes, too, will require to place themselves at different distances, so as to obtain the greatest degree of magnifying power with distinctness, according as individuals are long or short-sighted.