SCIENCE 



Friday, July 13, 1900. 



Single Copies, 15 cts. 

 Annual Sdescription, 85.00. 



A NEW FEATURE 



OF OUR 



Continental Microscopes 



IS THE 



DUST PROOF FINE ADJUSTMENT 



Old Form 



New "QUEEN" Form 



On all styles of Continental Microscopes the Fine Adjustment has always been exposed at 

 the most vital point, i. e. , the bearing surfaces of the prism. 



Fine particles of dust and grit lodging on the oiled bearing surfaces, eventually cause these 

 parts to wear and bind. Laboratory directors, everywhere, have experienced trouble on this 

 account. By means of a simple, yet efficient device we have rendered our fine adjustment 



ABSOLUTELY DUST PROOF 



Full particulars in Catalogue B-M. 



SCIENTIFIC INSTRUMENTS OF EVERY DESCRIPTION 



QUEEN &, CO., Inc. 



J. G. GRAY, President 



59 Fifth Avenue, New Yorl< 

 480 Monon Bldg., Chicago 



1010 Chestnut St., Philadelphia, Pa. 



