20 ELEMENTARY PHOTO-MICROGRAPHY. 



The projecting lenses mounted in the focussing 

 tube of the lantern are not required, and may there- 

 fore be removed before commencing, and the 4in. 

 condenser alone used. The prepared object is put 

 into the clips, and the ground-glass into the groove 

 at the opposite end. The object is focussed! 

 sharply by means of a focussing glass the naked 

 eye is quite unable to discern the point of best 

 definition and another piece of ground-glass is 

 interposed near to the object, but not close to it, to 

 distribute the light and secure even illumination of 

 the field. The ground-glass should stand between 

 the object and the lantern (C, fig. 5), and must be 

 far enough from the object to be out of focus, or 

 the rough surface of the glass will be shown in a 

 coarse background on the negative. 



We are now ready for the exposure. A cap is 

 placed on the lantern, or a large piece of cardboard 

 put against it, to keep the light from, reaching the 

 camera, and all the lights are lowered. The dark 

 room lamp is lit, and the focussing screen gently 

 removed from the grooves, replacing it with the 

 dry plate and a black card behind that. There is 

 no> need of any covering cloth if the plate and card 

 fit nicely into the grooves. Then the lantern light 

 is turned up, and the cardboad or cap removed, let- 

 ting the beam of light play full on the object for as 

 many minutes as may be necessary. Information 

 on this point will be given under the head of 

 " Exposure." Again the lantern is capped, the light 

 lowered, and the plate is removed to be developed 



