OBSERVING WITH AND MANAGING ENGISCOPE. 201 



also, by the help of the joint, v, until you get a good 

 spectrum of light upon your slider. (It will be well, in 

 the first instance, to form an image of the window upon 

 your object, and then to push the illumination a little 

 closer to it, so as to obliterate the image.) You will in 

 this way get the maximum of brightness : The crown of 

 the convex side of the bull's eye, or condenser, when 

 properly adjusted, will be about an inch, or an inch and 

 a quarter, from the object. 



If you think it more commodious, you may attach the 

 condenser to the stage, instead of the body (only, in this 

 case, if you move the optical part, you will lose your 

 light). To effect this, remove the setting of the lens 

 altogether from the split socket, by unscrewing the 

 joint, v, and fix it afresh, by means of its screw, into the 

 square bar, fig. 14, which insert into the square hole in 

 the stage. The adjustment is effected now by pushing 

 the illuminator up and down in the stage, combined with 

 the motion of its joint, v, as before. I think, however, it 

 will be found advisable only to attach the condenser to 

 the stage when artificial light is employed ; for, in this latter 

 case, the weight of an additional lens is applied to the 

 condenser, which might overload the body, if depen- 

 dent from it. 



If you wish to view opaque terrestrial living objects, 

 put them into the suitable live- boxes, with the pierced 

 covers, to admit air. These said boxes, with one or the 

 other of their lids, may be used to hold nearly any 

 object. 



