1210 



Megadiascope. 



of the microscope. For each objective it is best to use a special tube the length of which is so dimen- 

 sioned that on being inserted the/bjective is at approximately the correct distance from the object 

 and only requires a little correction. If it be desired to proceed rapidly from one magnification over 

 to another, a revolving collar for 3 objectives is a decided advantage. 



Very suitable objectives to employ are Hartnack's, System Nos: 2, 3, 5 and 7. 



With Hartnack No. 2 an image of 1,7 m. diameter is obtained at a magnification of x 170, 

 the distance from screen being 4,5 m. and the diameter of diaphragm 10 mm. 



With Nr. 3 an image of 2 m. diameter is obtained at a magnification of x 330, the distance 

 from screen being 4,5 m. and the diameter of the diaphragm 6 mm. 



With No. 5 the diameter of the image is about 1,8 m. with a magnification of x 900, the distance 

 from screen being 4,5 m. and the diameter of the diaphragm 2 mm. 



With No. 7 the diameter of the image is about 2 m. with a magnification of x 1300, the 

 distance from the screen being 4,5 m. and the diameter of the diaphragm 1,5 mm. 



In spite of this considerable magnification (which suffices for all purposes) the images are 

 very bright. The magnification can be measured in a very convenient manner by placing on the stage 

 an object micrometer (1 millimeter divided into 100 parts) and measuring on the screen, with a ruler, 

 the number of millimeters taken up by the magnified millimeter on the screen. The magnification is 

 thus ascertained direct. 



In projection with an ocular the ocular-tube is slipped into the tube of the projection micro- 

 scope. The objectives are either contained in a revolving collar or are screwed to the ocular tube. 

 Greater magnification is obtained when an ocular is used. The coarse focussing of the objectives is 

 made by rack and pinion on the tube, and fine focussing is obtained by means of a micrometer screw. 



Any disturbing light is kept off by curtains fitted to a drop board. 



Fig. 9. 1 : 10. 



Projection of microscopic Preparations with a collapsible Stand Microscope. 



Fie;. 8. 



CO 



5 



o> 



6. Projection of Microscopic Preparations with a Stand Microscope (Fig. 8). 



Micro-projection can also be carried out with a swinging stand microscope as shown in F i g. 8. 

 The most suitable microscope stand for the purpose is that used for micro-photography and projection 

 (No. 9543) which is illustrated in Fig. 8. This stand can be used equally well for all microscopic 

 work in conjunction with subjective observation. It has a rotating vulcanite stage (which can be 

 centred) and the usual condenser; it can however be supplied with detachable condenser also. Instead 



Cl. 4G66. 46S5, 4686. 



