3T4 The Miceoscope. 



rotation about the flame, or the oil reservoir itself can be rotated 

 so that the edge of the flame may be utilized, an advantage which 

 no microscopist would willingl}' abandon after experiencing its 

 benefits, and the entire lamp may be adjusted to any height or 

 angle of inclination at almost a touch. It is also provided with 

 blue and ground glass to modify the illumination, which is 

 again modified by a bull's eye nearly three inches in diameter. 

 The draft is ample, and the light steady and easily manageable. 

 One of the most acceptable features is that excellent efl'ects of 

 oblique light may be obtained without altering the position of 

 the mirror or the sub-stage condenser. This is an acceptable 

 gift to the microscopist with a diatom on the stage, as he can 

 so easily examine it under oblique light without putting him- 

 self to the trouble of changing the place of the mirror or of the 

 condenser, and without losing the influence of the sub-stage 

 accessory. The effects are obtained by rotating the oil reser- 

 voir and of course the flame, the position of the bull's eye 

 remaining unchanged. The complete separation of the bull's 

 eye from the other parts of the lamp, while it is still held 

 firmly in place and in focus, will be appreciated after a single 

 trial, as it enables the microscopist to use it or to turn the 

 lamp around and take the light direct from the flame in almost 

 any position, the whole procedure being performed without a 

 touch of the mirror or of the sub-stage arrangements. With 

 one hand the microscopist is able to turn the lamp exclusive of 

 the bull's eye, and thus watch, through the instrument, the 

 effects of the oblique light and of its withdrawal. By turning 

 the whole lamp on its heavy base and rotating the oil reservoir, 

 the effects of illumination without the bull's eye may be had, 

 while with the finger on the metal jacket the flame may be 

 rotated so that the edge or the broad side may be used and 

 their effects studied. The new lamp is not only an ornament to 

 the work table, but it must be an acceptable acquisition to the 

 working microscopist. Effects may be readily obtained with it 

 that with other microscopical lamps must be had with consider- 

 able trouble or not at all. 



Acknowledgment. — To Mr. Geo. Rust for a slide of fossil 

 diatoms from Denver. 



