Probably no work on microscopy has ever been written without including several paragraphs, or even an entire chapter, on the care of the eyes. In earlier times when lenses and illumination were less perfect than at present, eye-shades of varying construction were in common use. These usually were intended to afford a blank surface to shield the unused eye, and consisted of a flat piece of board, fiber, or metal with a perforation at one side to admit the drawtube which supported the shade. Such shades have been designed by Gage, Ward, Pennock, Clark and others. Some of these are illustrated in Figure 1.
Laboratories are now constructed with large windows which permit an abundance of light to flood the microscopic table. When one is working before such a window, the diffused light tends to render less distinct the image seen in the microscope, and very fine details may be