SCIENCE 



>Jew Series. 

 Vol. ]X. No. 210. 



Friday, January 6, 1899. 



.=<iNGr,E Copies, 15 cts. 

 Annual Subsckiption, S5.00. 



Static Machines 



for all purposes. 



X=Ray Apparatus 



and Supplies. 



SEND FOR BULLETIN No. 24. 



SWETT & LEWIS CO. 



9 Bromfield St., Boston, Mass. 



•vrr IJ? ' jl We bave jnst purobased a fine assortment of oraDge-yello'lT, well crystallized speci- 



W 'ULl.£6113.X6i mens, tbe last tbat can be obtained from tbe famous Mammotb GokUMiue of Pinal 



County, Arizona ; and offer tbem at prices ranging from 25c. to $12. Tbe latter, a magnificent specimen, 



5x3o inches, tbickly strewn with beautiful crystals. 



^Y J • 'J. from the same mine. This interesting lead vanadate appears glossy-black in surfaces 



V QiI1.3>U,m].T6 covered with minute crystals, reddish-brown in specimens with medium-sized ones, 



and brownish-yellow in those with large liexagonal prisms. Prices from 50c. to §10 for a large showy specimen 



Ward's Natur al Science Estab lishment, 28 to 40 College Ave , Rochester, n. y.- 



MINIATURE INCANDESCENT LAMPS. 

 MINIATURE LAMP RECEPTACLES. 

 ^ j X-RAY TUBES AND APPARATUS. 

 FLUOROSCOPES «^ 



Catalogues on Application. 



Edison Decorative and Miniature Lamp Department, 



(General Electric Company, ) 



HARRISON, /v. J. 



Biddle's Bulletin for 1899 



I began to publish this eight-page paper in April, 1898. It has not changed in size but there 

 is improvement in quality, I hope. For 1899 I shall try to make it still more interesting. 

 It should prove of real value (much greater than the cost of a yearly subscription) to all who 

 are interested in Scientitic Apparatus — Physical Apj)aratus, Electrical Measuring Instruments, 

 Projection Apparatus, X-Ray Apparatus, Psychological Apparatus, Storage Batteries, etc. 

 Some have received the P.lilletin free until now but I can't be e.xpected to keep that up. 

 T!te subscription price is 50 cents a year. It should be remitted at once for 1899. Smnple copy 

 upon request. 



specialist in JAMES Q. BIDDLE, 



Scientific and Electrical Insiruments. 909 Drexel Building, Pliiladelphia. 



