SCIENCE 



[Vol. XV. No. 364 



Sprague Clectric Rail^w^ay and Motor Company. 



Bearings Self Oiling, 

 NON-SPARKING IN OPERATION. 



Lightest Weight Consistent with 

 Highest Efficiency, 



SIMPLE IN CONSTRUCTION, 

 Not Liable to get out of Order- 



Commutator Wear Reduced 

 to a Minimum, 



16 and 18 BROAD STREET, NEW YORK. 



li Wimclerlicli & Co., 



868 BROADWAY, 



NEW VORK, 



Invite special attention to their latest 

 importations of Modem Etchings, En- 

 gravings, Brown's Carbon Photographs 

 and Watercolor Paintings, also to their 

 large collection of Rare English Mezzo- 

 tints, Fancy Subjects by Bartolozzi, 

 old Line Engravings, and Original 

 Works by Rembrandt, Durer, and other 

 old masters. 



WALKER PRIZES IN NATURAL HISTORY. 



The Boston Sodety of Natural History offers a first 

 prize of from S6o to Sroo. and a second prize cf S50, for 

 the best memoir, in Engiisfi. on one of the following sub- 

 jects : I. Oil the Adaptive Resemblances of Plants in 

 Different Natural Orders. 2. On the Processes Involved 

 in the Production of Soils. Memoirs must be handed to 

 the Secretary before April 15th, 1890. Prizes will not be 

 awarded unless the papers are deemed of adequate merit. 

 For further particulars apply to 



T. WALTER FEWKES, Secretary. 



Boston, Mass., Dec. iSth, 1S89. 



One Tlioiisand Dollar Prize ! 



THE AMERICAN SECULAR UNION cffer a prize 

 of ONE THOI S.\ND DOLLARS for the best essay, 

 treatise, or manual, to aid teachers in our Public 

 Sclioels Id iusiructlrg children iu the purest prin- 

 ciples of moi allty without Inculcating religious doc- 

 trines. For particulars apply to E. B. WESTBROOE, 



Philadelphia, Nov. 1889. irOT c xford St. 



mm 



(C\ IN THE WORLD, i 



5y?. 



Lsed by thousands of first-class 

 lechanicg and by such manufactn 

 rers as Pullman Palace Car Co., 



Mison ^ Hamlin Organ and Piano 



'To ic &c. 



Repairs Everything. 



Its success has brought a lot of 



_ . :_ . _,. ^ 



lat THE 



8*3 Liquid 



lanuf aetured solely by the 



RUSSIA CEMENT CO. 



GLOUCESTER, MASS. 

 Send 1 Oc. and dealers' card who 



WHAT IT BUYS 



i;6^3^ Namely, the money paid in premiums to 



XHE "TRAVELERS 



By over 100,000 Men every year. 



OF HARTFORD, CONN^ 



THE PAYMENT OF 



Over $1,000,000 a Year (Claims on One-Seventh ] Under 

 of all Insured), - ACCIDENT 



Over $12,000,000 altogether, j PollCWS. 



Over $550,000 a year (in Death Claims and 

 Endowments), 



Over $5,500,000 altogether. 



Under 



LIFE. 



Policies. 



ASSETS, $11,528,000, 



SURPLUS, $2,365,000. 



JAMES G. BATTERSON, President. RODNEY DENNIS, Secretary. JOHN E. MORRIS, Assistant Secretary. 



