1894.] MICROSCOPICAL JOURNAL. 89 



In the foregoing table we give, at the side of the previous 

 quotations [in brackets], the prices at which the apochromats 

 will be sold henceforth. 



At the same time we beg to announce a modification con- 

 cerning the achromitic objective 1-12 (Homogeneous Immer- 

 sion). This objective which we used to construct either with 

 aperture 1.20 or 1.30, will in future be only supplied with one 

 aperture — 1.25 in the mimimum — at the price of M. 160. 



Carl Zkiss, 



Jena, Feb. 15, 1891. Optische Werkstatte. 



Substage Attachment. — Thesubstage attachment described 

 by G. W. Brown, Jr., in the December Journal, is made by Jos- 

 eph Zentmayer of Philadelphia, and is sold in connection with 

 the Abbe condenser and iris diaphragm for about S30. For fur- 

 ther particulars apply to Joseph Zentmayer, 209 South 11th 

 Street, Philadelphia. 



MICROSCOPICAL MANIPULATION. 



Transmitting Slides. — The tin-boxes in which the type- 

 writer ribbons are packed are 3i long by 1^ inches wide and 

 make most excellent boxes in which to transmit slides. There 

 is just room enough to insert the slides wrapped in cotton or in 

 blotting paper and no damage can be done by the mailing or 

 by the pressure to which packages are subjected in mail bags. 

 This is of especial importance when slides are sent across the 

 ocean. 



To Centre a Slide. — A "village druggist" sends us the follow- 

 ing: 



Put into a watch glass a pinch of prepared chalk and enough 

 methj'lated spirit to make a thin white-wash. Mix, and with a 

 camel hair pencil smear over the central part of both surfaces of 

 the slide. Stand on edge to dry. Now make a tool something 

 like a carpenters marking gauge in miniature. Just a little rod 

 of wood about 1-5 inch in diameter and 3 inches long with a lit- 

 tle block slid and fixed on it. With a triangular needle (which 

 every one should possess), drill two holes in the rod; one, say 

 6-10 inch from one face of the block : the other 1 4-10 nich from 

 the other face. Into these holes fix little pegs of woo 1 to pro- 



