Knight's American mechanical dictionary : a description of tools, instruments, machines, processes and engineering, history of inventions, general technological vocabulary ; and digest of mechanical appliances in science and the arts . smaller power. Though natural sunlight is to be preferred, it may be some-times necessary, when this is wanting, to employ artificial iilu-mination : for this purpose, theelectric. the magnesium, and theoxycalcium lights liave been used with success. Of these, theelectric light is the best, and for its production Dr. W. employsa Duboscq lamp, operated by a batte
Knight's American mechanical dictionary : a description of tools, instruments, machines, processes and engineering, history of inventions, general technological vocabulary ; and digest of mechanical appliances in science and the arts . smaller power. Though natural sunlight is to be preferred, it may be some-times necessary, when this is wanting, to employ artificial iilu-mination : for this purpose, theelectric. the magnesium, and theoxycalcium lights liave been used with success. Of these, theelectric light is the best, and for its production Dr. W. employsa Duboscq lamp, operated by a battery of 50 small Grove ele-ments, 10 in a cell The magnesium light affords an ilhimination similarto white-cloud light, or that of the sun after passing through groundglass, and is well alaptcd for photographing soft tissues withpowers less than diameters : tbereare no interference phe-nomena, but with powers exceeding 1,000 diameters the time ofexposure becomes inconveniently long. Fig. 3(384 shows the arrangement employed. The magnesiumlamp a stands on a shelf fastened to the wall: the comlenser *•concentrates the light on the achromatic condenser of the mi-croscope c, which stands on a table e supported upon three lev-. Microphotographic Apparatus {ivith Magnesittm Lamp). eling screws. The image received on the plate-holder s supportedon the table / is photographed precisely as in fhe case ofthe electric light. The same focusing apparatus d is em-ployed, and the ammonio-sulphate cell is invariably in-serted. See Dr. Woodwardsarticles, American Journalof Science and Arts, (Second Series), Also-Reports tothe Surgeon - General,1870-71. Fi^ 3685 shows a photo-mierographicapparatus fromOtto Buchlers Atelier undApparat des Photographen fit represents the mirror, 6the object-holder, r the mi-cro.«cope, and d the dark-chamber, on top of which Isthe plate-holder. The ad-justments are three: one forthe object-holder, one for themicroscope, and a third forg
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