APR 15 1905 



SCIENCE 



New Series. 



Vol. XXI. No. 537. 



The New Reflecting Projection Lantern 



for showing on the screen, photos, engravings, sketches, colored prints, flowers, 

 specimens, mechanical models such as the works of a watch, the dial of a galvanom- 

 eter, etc., all brilliantly lighted in natural colors. Cuts in books may be shown 

 without injur}' to the book. The outfit is arranged to show both opaque objects and 

 lantern slides, and the change from one to the other may be made instantly. 

 Attachable to any electric magic lantern. Send for circular and list of Educational 

 Lantern Slides. 



WILLI7=S[7V^S, BROWN St EKRLE 

 Dept. M. 918 ehestnut St., Philadelphia, Pa. 



^ TIMELT BOOK OF UNQUESTIONED AUTHORITT 

 GEN. HENRY L ABBOT'S 



Problems of the Panama Canal 



Including the Physics and Hydraulics of the. River Chagres, the Clima- 

 tology of the Istlimus, and the Cut at the Culebra. By BRIG.-GEN. 

 HENRY L. ABBOT (U. S. Army, Retired), Late Colonel, Corps of 

 Engineers, Late Member of the International Comite Technique, and Con- 

 sulting Engineer of the New Panama Canal Company. 



Cloth, 12mo, $1.50 net {postage 12c.) 



A clear, exact and readable account of the Canal since the failure of the French Company, 

 covering the work of the New Company and its negotiations with the U. S., terminating in its 

 sale. It is written by the one man who, from the closest official association with every stage 

 of the reorganization of the Canal works, is in a position to know the ab.solute truth. He explains 

 the facts as to rival routes, health conditions, and projected works, in an unrivalled manner. 



THE MACMILLAN COMPANY. Publishers, 64-66 Fifth Ave., New York 



