Page:Popular Science Monthly Volume 58.djvu/588

580 which a plate (marked D) was joined, carrying the magnifying glass. The latter is indicated in the circle above the letter D, near the tail fin of the fish. The eye was applied close to this circular magnifying glass, which was brought into position and adjusted by means of screws. The two small sketches show a front and a back view of another one of his microscopes. The small circle shows the position of the lens inserted in a metallic plate. On the opposite side was a sort of object holder, whose position was controlled by screws. In some instances, he had a concave reflector with a hole in the center, in which his magnifying-glass

was inserted, and, in this form of the instrument, the objects were illuminated by reflected and not by transmitted light.

His microscopic observations were described and sent to learned societies in the form of letters. "All or nearly all that he did in a literary way was after the manner of an epistle," and these were so numerous as to justify the cognomen, 'The man of many letters.' "The French Academy of Sciences, of which he was elected a corresponding member in 169?', got twenty-seven; hut the lion's share fell to the young Royal Society of London, which in fifty years—1673-1723—