SCIENCE 



New Series Fptoav Fprrttary 9'> 1Q1S Sinolk Copies, 15 Cts. 



Vol. XLVII NO. 120S FRIDAY, J? EBRUAR\ Z-, iyi» annuai Sdbsoiuption, $5.00 



To Our Patrons 



We wish to thank you for your co-operation during the past 

 year and for your patient consideration, as we have endeavored 

 to supply the continued heavy demand for our inetrumenta 

 under unprecedented production conditions. 



At this critical period in onr nation'B history we must each 

 discover what our country requires of us ; then do our particular 

 bit, gladly, to help win the war as speedily as possible. 



It has not been difScult for us to discover our bit, for 

 optical instruments are the eyes of the modern army and navy, 

 and we are bending all our energies to the endeavor to meet the 

 requirements. 



We are confident that you, too, are adjusting yourselves to 

 prevailing conditions, cheerfully and optimistically, for pessi- 

 mism never promoted any cause. Yours is a vocation the 

 country needs in wartime as well as in peace, and we hope to 

 continue to assist you in the solution of your problems. 



May we thus work together, then, for the best interests of 

 humanity — first, to win the war ; second, to maintain the mo- 

 mentum of all worthy activities in the nation, looking steadily 

 to the day when the war shall cease. 



Bausch ^]pmh Optical (5. 



409 ST. PAUL STREET ROCHESTER, N.\: 



New York Washlngrton Chicago San Francisco 



Leading American Makers of Microscopes, Photomicrographic and Projection Apparattts 



(Batopticons), Photographic and Ophthalmic Lenses, Stereo-Prism Binoculars 



and other High Grade Optical Products. 



