Megadiascope. 



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horizontally placed carbons and the parabolic mirror. In order to screen from the object to be pro- 

 jected the heat given off at the arc 

 and that reflected by the concave 

 mirror, a mica disc and water 

 trough are suitably arranged. The 

 latter lias a cooling coil and inlet 

 and outlet for the water. The 

 cooling trough can therefore be 

 filled with a constant supply of 

 fresh running water, or a solution 

 of ferrous ammonium sulphate can 

 be poured into the trough, this 

 solution absorbing the heat to a 

 great extent; the solution can then 

 be cooled by passing cold water 

 through the cooling coil. 



The apparatus have an optical bench 

 with objective carrier and objective, 

 and an adjustable stage for holding 

 the objects of projection. The optical 

 bench is composed of two round metal 

 rods maintained parallel by end pi 



When not in use this bench can be 

 pushed completely under the sub-- 

 structure, thereby rendering possible 

 the setting up and projection of 

 apparatus in front of the condenser 

 independently of the bench. The 

 bench is supported at its front end by 

 a stand to prevent sagging when 

 heavy instruments, etc. are placed 

 on it. 



.liascope, small Model, with Table and Regulating Resistance, 

 and Arc Lamp with auto-regulator. Fig. -2. l:'2n. 



Megadiaoeope, small Model, with hand-regulated Arc Lamp. Fig. 3. 1 : 15. 



A special apparatus is provided for projecting horizontal 

 objects, and is placed on the megadiascope (see Fig. 6). 



For projecting opaque, flat objects and woodcuts, drawings and other illustrations the Mega- 

 scope is used (F i g. 26), which is placed upon the megadiascope in place of the horizontal type projector. 



Cl. 3272. .',L>i5. 



