The Microscope. 7t 



also of a narrow strip of wood, and supporting a sheet cylinder 

 which runs parallel with the support. The upright is grooved 

 on its front surface, and into this is fitted a slot which allows 

 the terminations of two narrow arms to slide upward and down- 

 ward; the lower of these arms terminates in front in a small cir- 

 cular opening for the reception of the lens to be used in magni- 

 f3dng. The upper one terminates in a circular plate which is 

 perforated by an opening equal in size to that of the opening for 

 the lens in the termination of the lower arm below; this circular 

 plate is the carrier of the slide bearing the preparation. On the 

 back surface of the upright is a large piece of canvas board (not 

 shown in the illustration), which may be made firm by cutting a 

 hole in the centre of its upper portion so that it will fit the end 

 of the sheet cjdinder used for conducting the rays of light. The 

 purpose of this board is to cut off all the ra3's of light except 

 what passes into the cylinder. An ordinary petroleum lamp 

 with a good burner, a gas jet or an electric lamp may be the 

 source of the light. I have found a small lamp with a reflector 

 will answer every purpose admirably. 



The slide bearing the object to be drawn, having been placed 

 on its bearer, the little circular plate and the light in position, a 

 piece of drawing paper is placed on the stand beneath the lens. 

 The next thing to decide is how large you wish to make the 

 drawing, and so use a correspondingly weaker or stronger lens. 

 Then with the lens in position you focus by sliding the arm 

 bearing the lens, the upper arm bearing the slide being fixed, 

 upward or downward until an accurate focus is shown to be ob- 

 tained by a delineation of the object on the slide on the paper 

 beneath. 



Although the canvas board will cut off sufficient of the rays 

 of light to allow the outlines to be well marked, it will be found 

 that working in a dark room with no light save the one used for 

 the apparatus will be more conducive to a clear delineation. By 

 regulating the height of the arm, and by changing the lens, any 

 magnification between two and fifteen times can be made. 



Frequently it will be desirable to make only the outlines of 

 the drawing with the apparatus, and then to fill in the details 

 from the microscope; for instance, if one should desire to make 

 a drawing of the medulla spinalis in three colors, the outlines 

 could be made with a pencil and then erased till only a guiding 



