254 THE AMERICAN MONTHLY [Aug 



F. Shilling-ton Scales, F. R. M. S. in Science Gossip 

 says : Our object is to make this column as interesting 

 and as helpful as possible to our readers, by keeping- them 

 informed of various matters of interest in the microscop- 

 ical world, especially with reference to methods of work. 

 We propose in future to lay greater stress, from time to 

 time, upon the improvement of the microscope and its ac- 

 cessories. We desire, in fact, to make this column a valu- 

 able record of the progress of the microscope, of new or 

 modified stands, objectives, apparatus, etc. The present 

 keen competition amongst opticians, especially among-st 

 the limited few who are in the front rank, and with whom 

 workers are mostly concerned, gives rise to constant pro- 

 gress. It will be our endeavour to keep our readers ad- 

 vised on these points without fear and without favor. 



MICROSCOPICAL APPARATUS. 



New Achromatic Condenser. — Although the Abbe Con- 

 denser, or, as it is often called, Illuminator, is recog-nized as 

 being- suitable for most g-eneral practical work, mainly on 

 account of its being- easy to use, yet for more critical work 

 a well corrected condenser becomes a necessity. Messrs. 

 Beck have broug-ht out a new condenser in high-power work 

 that is achromatic and has a numerical aperture of 1 N. A. 

 This is the maximum that can be obtained without having 

 the front of the condenser in immersion contact with the 

 under surface of the slide, and its aplanatic aperture ex- 

 ceeds '9 N. A. It is thus greatly superior to the ordinary 

 Abbe Illuminator. The front lens is removable to make a 

 low-power condenser. An Iris diaphrag-m and a swinging- 

 arm, with rotating- fitting for colored glasses, or stops, are 

 provided. A bracket is ing-eniously added at the bottom of 

 the mount, into which the optical portion may be screwed, 

 and the whole condenser thus reversed. This is often a 

 convenience. The price of the complete condenser is $15 

 but with Iris dirphrag-m only $12. 



New Tripple Nosepiece. — The Messrs. Beck have also 



