Depressions appeared as elevations, and vice versa, or, as we must say after Charles Wheatstone, it presented a pseudoscopic impression; this quality, however, was not recognized by the microscopists of the time.
Early opticians and microscopists gave their chief attention to the improvement of the simple microscope, the principle of which we now explain.
This oil is largely used by microscopists in what is known as the "oil-immersion lens."
This minuter study had two origins, one in the researches of the medical anatomists, such as Fabricius (1537-1619), Severinus (1580-1656), Harvey (1578-1657), and Tyson (1649-1708), the other in the careful work of the entomologists and first microscopists, such as Malpighi (1628-1694), Swammerdam (1637-1680), and Hook (1635-1702).
He described the reflecting goniometer in 1809 and the camera lucida in 1812, provided microscopists with the "Wollaston doublet," and applied concavo-convex lenses to the purposes of the oculist.