1892.] MICKOSCOFICAL JOURNAL. 15 



If the plan commends itself to our friends, we hope to hear so. And 

 we shall, of course, have to curtail the publication of lengthy papers in 

 order to make more room for our resumes. 



The publication of matter for amateurs and beginners has always been 

 demanded by certain classes of subscribers. There are now a sufficient 

 number of books of this character, and our inexperienced friends ought 

 to make use of such books so as to enable us to use our space for mat- 

 ter alluded to in this article. 



We shall, however, try to bring our matter within the grasp of all, 

 whether expert with the microscope or not. 



A copy of " Carpenter on the Microscope " is indispensable for every 

 person interested in the subject, young or old. By the aid of it, ama- 

 teurs will be able to interpret much that appears in the current litera- 

 ture. The new edition by Dr. Dallinger is just out and published at 

 $6.50 per volume, but as an inducement to our friends to purchase for 

 the purpose indicated, we will supply it as a premium to those remit- 

 ting for their 1893 subscriptions (all previous subscriptions having been 

 paid) for $4.75 per volume. To all others our price is $5.00 per vol- 

 ume. 



To any amateur becoming a new subscriber we will send upon appli- 

 cation a free copy of White's •• Microscopy for Amateurs." 



With thanks to all our friends for their past favors and indulgences, 

 and a promise of hearty co-operation in all that will advance the art we 

 love anil the sciences to which it ministers, we enter upon the new year. 



MICROSCOPICAL APPARATUS. 



A New Polarizer. — Owing to the growing dearth of Iceland spar 

 something must be done to maintain our powers of polarization. Prof. 

 S. P. Thompson proposes producing polarized light without the Nicol 

 prisms. As described to the British Association, he reflects the light 

 from a black glass mirror, whose surface is covered with a plate of 

 clear glass. Light from a lantern is reflected onto the mirror with a 

 total-reflecting prism. A second reflecting prism, most carefully an- 

 nealed turns tlie polarized light back into its original axis. 



Glass for Immersion Oil, — Behrens uses a bottle made by Zeiss, 

 which is cylindrical, 60 mm. high and 30 mm. wide. The neck of the 

 bottle is very wide (15 mm.) and is ground. Upon the neck fits a cap 

 carrying a glass rod, which reaches to the bottom of the bottle. At 

 the upper end of this solid rod is a glass hemisphere, which is cemented 

 by shellac into a hole in the cap. It is i^ mm. in dia. and 60 mm. 

 long. At the lower end of the rod is a small glass ball (3 mm. dia.), 

 which prevents the oil dropping ofl'. — Z.f. W. Mikr. 



Making Lenses. — The bit of glass to be formed into a lens is fas- 

 tened b}' means of pitch to a small block of hard rubber so that it may 

 be more readily handled. It is ground by being pressed against a rap- 

 idly-revolving metal tool, whose curvature is equal and opposite to that 

 desired in the lens. This is known as the " rough tool" and is made 

 of cast iron. It is mounted on a vertical spindle, and is kept moistened 

 with emery and water. Several grades of emerv are used in succes- 

 sion, changing from coarse to fine as the grinding proceeds. As a re- 



