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BAUSCH & LOMB 

 BALOPTICON MODEL D. 



IV/IODERN methods in the class-room mean the simple, 

 ^ direct and easy means of conveying facts so that the 



pupil will " grasp *' them readily. 



Q That is why the Balopticon Model D appeals to all teachers. 

 It abridges a long and tedious course and brings teacher, 

 pupil and subject into the most intimate, interesting, illumin- 

 ating relationship. 



^ No. 4200 Balopticon Model D complete with 6 inch equiv- 

 alent focus Bausch and Lomb Standard Projection Lens, 

 $75.00. With 10 inch Lens. $80.00. 



fl PRISM is a little populat science monthly. Send for copy D, free. 

 ^Om name on a Laboratory Apparatus, Photographic Lens, 

 Field Glass, Microscope, Scientific or Engineering Instru- 

 ment is OUT Quarantee. 



Bausch & Lomb Optical Co. 



To Know That 



J^Cocoa 



Is the BEST in the World 



means to buy a Can at 



your drocers and try it. 



May cost one-tenth of a cent 

 more per cup than some, and 

 less per cup than some others 



But remember 



such PURITY 



QUALITY 



and FLAVOR 



as in 



Cocoa 



Stands 

 UNEQUALLED 



^lustration shows B-in. with pneumatic dock. 



Refracting and Reflecting 



Astronomical Telescopes 



standard and Portable 



Visual and Photographic 



OBJECTIVBS 



Computed by our associate^ 



DR. F. R. nOULTON 



{Chicago University) 



OBSBRV ATOR IBS 



specula, Planes, Eyepieces, etc. 



Photographs and Circulars on request 

 LOHflANN BROS. 



QREENVILLE, OHIO : : : : U. S. A. 



