SCIENCE— ADVERTISEMENTS 



Polariscopes 



for the sugar 



idustr 



chemical laboratories and 

 the physician. 



Refractometers 



for testing butter, margar- 

 ine and other oils and fats. 



These are now being furnished through 

 us as the exclusive distributors of optical 

 and scientific instruments manufactured 

 by C P. Goerz of Berlin. 



We have new designs. All instruments 

 are of the highes precision. 



Correspondence is invited. 



C. p. Goerz American Optical Co. 



319 P East 34th Street, New York City 



FREAS CONSTANT TEMPERATURE 

 ELECTRIC VACUUM DRYING OVEN 



With improved type of cylinder head, mak- 

 ing removal more easily accomplished. 

 For sale by all leading dealers. 



Manufactured by 



The Thermo Electric Instrument Co. 



8 Johnson Street, Newark, N. J. 



SPENCER 



Attachable to anj' standard compound micro- 

 scope and possessing many of the advantages 

 of the Mon-objective Binocular. 



The optical system in this instrument is, in 

 all re.'jpects, identical w^ith that employed in 

 our binocular microscopes except that a nega- 

 tive lens has been introduced to compensate as 

 far as possible for the increased tube length that 

 results from adding the binocular body to the 

 tube of the ordinary microscope. 



The characteristic features include: 



CATALOGUE 



1. Convenient adjustment for pupillary distance. 

 II. Dial register for individual settings. 

 ill. Convergent tubes, giving normal vision. 

 IV. Independent focusing of oculars. 



SPENCER LENS COMPANY 



MANUFACTURERS 



Microscopes, Microtomes, Delineascopes, Optical Glass, Telescope 



Discs and Lenses, Optical Measuring Instruments, Etc. 



BUFFALO, N. Y. 



CLR DIOCULAR NO 440 

 $50.09 

 SENT ON REQUEST 



