Megadiascope. 



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Mk-roprojection with the Projection Microscope. 

 Fig. 7. 



Microprojection with the Projection Microscope, without ocular. 



Fig 7 a. 1 : ,=>. 



In use the horizontal projector is placed on the megadiascope in the manner shown in Fig. 6, 

 after a wood cover has been taken off. 



By means of the horizontal projection apparatus, horizontally lying objects such as Berg- 

 hoff's apparatus for magnetic force lines, the apparatus for magnetic 

 distribution in magnet bars, the dip needle, etc., etc. can be projected in a very 

 beautiful manner. 



The condenser lens is amply dimensioned, being 150mm. in diameter, in order that the objects 

 need not be too small or the magnification too great. With a magnification of x20 an image 3 m. 

 in diameter is obtained on the screen, the distance of the apparatus from the screen being 4,5 m. 



Fig. 6 shows the erection of a galvanometer with transparent scale No. 21588 of our List 

 Xo. 21) in conjunction with the horizontal projection apparatus. 



5. Microprojection with the Projection Microscope. 



The projection of microscopical preparations (or microprojection) plays a very important parr 

 in education. The Projection Microscope is employed for attaining this end (see Fig. 7 and 7 a). 



On a special slider a pillar is fixed which carries the stage and the tube. Illumination is provided 

 by the pencil of light issuing from the condenser. 



In order to obviate the stage and the preparation becoming considerably heated by the heat 

 rays coming from the condenser, the stage is constructed hollow and is provided with water inlet and 

 outlet in order that it may be kept cool by flowing water. Moreover, the stage is insulated where 

 fitted to the stand and is projected from heat rays by a mica disc. The tube for the flowing water 

 is connected to the cock at the lower end of the stage: the outlet at the upper end of the stage being 

 connected by a length of piping with the large water trough of the megadiascope. The water thus 

 flows first through the stage and then through the trough. The stage has a rotating diaphragm with 

 apertures of 10, 6, 3, 2, 1.5 and 1 mm (0.39, 0.23, 0.11. 0.078, 0,058 and 0.039 ins.) corresponding 

 to the different magnifications of the objectives. The objects are held to the stage by a spring clamp. 



The stage is shaped in such manner that the object holder projects slightly in order that the 

 preparation may be taken hold of by the fingers and moved to and fro a little, for the purpose of bringing 

 all parts of the same into the field of view (see Fig. 7 a). In the case of projecting without 

 an ocular the objectives are screwed on to short tubes with which they are inserted in the wide tube 



Cl. 4665. 3273. 



