JOURNAL OF THE 



[January, 



stage is placed a platinum spiral (see Fig. 3), which may be 

 heated by the electric current so as to raise the temperature of 

 an object under examination. The degree of the heat is easily 

 controlled by the rheostat, and it may be measured by means of 

 a spiral bimetallic thermometer. In the illustration (see Fig. 4), 

 r and S are ribbons of iron and brass, soldered together. The 

 inner end, a, is screwed to the stage close to its opening, m. 

 The free end, b, acts upon an index, d, which is pivoted at x, and 

 whose point traverses the graduated arc/g. 



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The rest of the article treats, in a full and interesting manner, 

 of the application of electrical illumination to photomicrography, 

 and describes a form of stand especially adapted to that depart- 

 ment of microscopical work. The details cannot be given here. 

 One or two facts, however, I must note, — the microscope has a 

 vertical position instead of the usual horizontal one, and the 

 illumination necessary for taking a most excellent photograph of 

 Pleurosigfna augulatum costs an electro-motive power of only 

 five volts. 



Dr. Stein concludes his article with an expression of confident 

 belief that the microscopist who has once employed the electric 

 light for his researches, will thenceforward use no other. 



