IV 



SCIENCE— ADVERTISEMENTS 



Hess-Ives Tint Photometer 



"Sokes All Color Problems" 



Write for Color Booklet 



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90-94 Maiden Lane 

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A few Industries in which 

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the Instrument has 



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ANNOUNCEMENT 



Biology Teachers will be 

 glad to learn that the Mar- 

 ine Biological Laboratory of 

 Woods Hole, Mass., has es- 

 tablished a branch at 

 Chicago. The new firm is 

 known as 



The General Biological 

 Supply House, Inc. 



Formerly The Chicago Biological Supply Honte 



5508 Kimbark Avenue 



CHICAGO, ILL. 



We shall supply all the 31. B. X. 

 materials and tnany lines never at- 

 tempted at Woods Hole. Get our 

 Catalogs at once. 



QUARTZ OPTICS 



WE HAVE JUST RECEIVED 

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QUARTZ CRYSTALS 



OF UNUSUALLY LARGE DI- 

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GLASS PRISMS AND LENSES 

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Take Your Optical JProblems to 



KOLLMORGEN OPTICAL 

 CORPORATION 



35 STEUBEN ST., BROOKLYN, N. Y. 



