126 



THE WORLD'S ADVANCE for JULY 



Your Apparatus 



Should Give You More 

 Than Actual Service 



It Should Give You a Sense of Pleas- 

 ure and a Pride of Ownership 



Radion Receiving Set, complete with ( r\ s A A 

 2,000 ohm head set and Perron Detector 4> L* O U U 



Clapp-Eastham apparatus costs 

 no more, and carries a feeling of 

 pride and security which attaches 

 only to a standard product of 

 established reputation. 



Our catalog fully describes and 

 illustrates a product manufac- 

 tured since 1 907, and is delight- 

 fully free from the usual adver- 

 tising superlatives. 



YOUR COPY WILL BE MAILED PROMPTLY ON REQUEST 



GLAPP - EASTHAM CO. 



143 Main Street, Cambridge, Mass. 



'11.50 



NO 

 WABBLING 



RUNS 

 STEADY 



Chambers Rotary Spark Gaps 



Gives a tone similar to a flute on 60 cycles. Our 

 spark gap runs on 110 D. C. or A. C. and is suitable 

 for % to 1 K. W. Motors furnished in two sizes 

 with % inch shafts. 



Full details of prices and sizes, etc., in our new illus- 

 trated catalog 3-24 sent on receipt of 5c in stamps* 

 F. B. CHAMBERS & CO., 2046 Arch St., PHILADELPHIA, PA. 



HIGH TONE ROTARY 



GIVES 600-CYCLE WHIS- 

 TLING SPARK LIKE A 

 QUENCHED GAP. 



Attains full speed in one 

 second; stops dead inside 

 of three seconds. 



More power can be ra- 

 diated at high - spark 

 frequency than at low. 

 Greater efficiency. 

 Light revolving d i t. - 

 charger allows high 

 speed without heating. 

 Signals easily read 

 through static. 

 Requires less sending 

 condenser. 



Send 4c in stamps 

 for latest Bulletin 

 "C" contains many new pieces of apparatus. 



Radio Apparatus Company of America 



Parkway Building, Philadelphia, Pa. 



DON'T BUY CATALOGS. 

 BEST IS 



FREE 



In addition to our most complete line | 

 of Wireless and Electiical experimental 

 goods, we now offer at tho lowest prices 

 in America in our Cyclopedia No. 15: 

 largo line of Sporting goods, comprising 

 Baseball and Tennis material: Foot-! 

 balls and Baseballs, low-priced Printing 

 Presses, students' Microscopes and Tele- | 

 scopes, Photographic goods, Model steam 

 Engines, low-priced Watches, Pocket- I 

 knives. Fretwork Outfits, Phonographs | 

 and Records, Air Rifles, Precision Lathes. 



E.I.CO.N.Y.; Gentlemen 

 Send at once big Cyclopedia 

 Catal. No. 15. I enclose 4c. 

 for postage. 



Rotary and Quenched Spark Gaps, 

 Violet-Ray H ; Kh Frequency Appa- 

 ratus. F"ans, Generators and Mo- 

 tors A large Wireless Code Chart; 

 7 pages Wireless Call letters; Tre- 

 atise on Wireless and 20 coupons 

 for FREE Wireless Course. 



THE ELECTRO IMPORTING CO. V AT1 Eiwn IT IN 



"Everything for the Experimenter" llllJ I 



229 FULTON STREET, NEW YORK 1VU * llll/ " M1 



'"THI LIW1ST CA.TALOG 



IMPORTING 



; w 



233 FULTON ST 

 ' -NEW -YORK 

 "'-; ' V .' 



CATAUIGl~15 



272 Pages. 

 658 Illustrations. 



2000 Articles. 

 Size.6Min.x5in. 

 Weight, ^ pound. 



For our Mutual Advantage mention The World's Advance when writing to Advertisers.^ 



