THE WORLD'S ADVANCE for JULY 



127 



f\UR NEW BIG 216 PP. CATALOH 



V ELECTRICAL and WIRELESS \*f+ J%fcA/\* 



IS THE EXPERIMENTER'S REFERENCE BOOK 



Thisj>reat catalog mailed to any one upon receipt of 6c. in stamps 



Are You Building Something ? 



. 6 CATALOG shows several hundred parts and 



Our No 



materials for building 



parts and sets of 



your own apparatus at home which 



have never before been listed. We do all the difficult work in 

 our factory and then you put them together. We have 

 JUST WHAT YOU HAVE BEEN LOOKING FOR. 



This Big Catalog Contains 



No. 7729 



THE AMCO NAVY TYPE RECEIVING TRANSFORMER 



Represents the latest advances made towards the ideal tuner and embodies the great- 

 est degree of perfection yet obtained. No greater value can be secured where ac- 

 curate selectivity, sensitiveness and finish are desirable. The illustration shown here- 

 with cannot possibly do justice to the instrument it?elf. The primary winding is 

 enclosed in a cabinet, the sides and top of which are polished hard rubber. Two 15 

 point switches are mounted on the front. One switch controls the primary in groups 

 of several turns and the other controls one turn at a time. The entire variation of 

 the primary is thus secured by the rotary motion of two knurled knobs rather than 

 the movement of a slider, and may be varied from 1 to 225 turns in steps of one 

 turn at atime. The windings are especially adapted to long wave lengths. The 



Complete description and prices of the latest 

 Electrical and Experimental Apparatus Storage 

 Batteries, Rectifiers, Transformers, Induction 

 Coils, Wireless Apparatus, Lamps, Flashlights, 

 Meters, X-Rays, Books, Tools, Electric Rail- 

 ways, Steam Engines, Water Motors, Dynamos, 

 Motors, Telegraphs, Telephones, Electrical Sup- 

 plies, Model Aeroplanes and Parts for building 

 your own apparatus. FREE with each catalog 

 a Treatise on Wireless Telegraphy, telling how 

 to put up an aerial, connect apparatus, together 

 with a Call list and Wiring Diagrams. 6c in 

 stamps will bring you this wonderful book. The 

 best catalog of wireless apparatus, etc., published. 



secondary is wound with green silk covered wire. The ends are HARD RUBBER, turned and polished. Secondary variation is secured by 

 a 12-point switch which makes it possible to secure a very fine adjustment. PRICE ONLY $15.00 



ADAMS-MORGAN CO., 12 ALVIN PLACE, UPPER MONTCLAIR, N. J. 



"THE ELECTRICAL EXPERIMENTER" 



The big electrical Magazine for those 

 who dabble in electricity and Wireless. 

 Chuck full of experiments. Intensely 

 interesting. Monthly prizeaof SS.OOfor 

 best experiments. Amateur Electrics, 

 wireless news. Complete Electric Course 

 etc. 50 to lOOillustrations. Only 5Oc a 

 year in U S. and Canada. On all 

 News-stands. Send for free sample. 



Electrical Experimenter 235 Fulton St.. N. Y. 



-TUNING COILS 



The Boston Two Slide Tuning Coll, 800 Meters $2.50 



Variable Condenser, 25 Aluminum Plates, Slide Type.. 2.75 



Write for catalogue and get acquainted with our goods 



A. W. BOWMAN & CO., 18 Devonshire St., Boston, Mass. 



WANT MORE SENDING POWER ? 



You can have it at remarkably little cost by using 

 our y 2 K-W Transformer. Has 30,000 turns, gives 

 you 13,200 volts. 

 Write for special proposition to wireless amateurs. 



PACKARD ELECTRIC CO., WARREN, 0. 



COMPLETE 



WIRELESS SENDING and 

 RECEIVING $1fl.lO 

 STATION 1V 



Receives hundreds 

 of miles. Send 8 

 to 20 miles. 



This remarkable 

 station consists of 

 a guaranteed 1%- 

 i n c h spark coil, 

 machine - turned 

 fluted spark gap, 

 our 1501 key, a 

 flat plate c o n - 

 denser a s s e m- 

 bled in an oak 

 case, a large ca- 

 p a c i t y ""-^^^^I^BSgggag^F helix, DPDT switch 

 500 - ohm po- ^**^;>5!3BSKSa^ tentiometer, buzzer and 

 switch to tell if your ^-^S^SSSigSa^ detector is working, buz- 

 zer battery in nickeled case, ^58r tubular condenser, our now 

 3-action cat-whisker detector, ^^ bare wire wound double slide 

 tuner, No. 30 silk wire wound large 6 capacity loading coil that 

 allows you to get Arlington and long wave stations. Send stamp 

 for our large catalog "G" of remarkable values. If possible call and 

 see our stock. THE HANDEL ELEC. CO., 138-140 Centre St.. N.Y. 



ROTARY SPARK GAPS 



This gap consists of a light, 

 durable, non-warping disc, on a 

 high speed 110 volt A. C. or 

 D. C. motor, mounted on a 

 white marble base, giving an 

 efficient, smooth running gap, 

 of neat appearance and having 

 a clear, musical tone. 



m* 



circular 



AULL-ZIEGLER WIRELESS MFG. CO., East St. Louis, 



Mascot Rotary Wheel with !/ 4 or % 

 inch Electrodes, $5.40. 



When you Buy Wireless Apparatus, look 

 for these TRADE NAMES and you will 

 get the BEST: 



"Beeko"-"Mascot"-"Dandy"-"Jove"-"Standard" 



THE Highest Quality at the Right Price. 



Get Your Name on our Mailing List for our new 



Catalog No. 36W. 



J. H. BUNNELL & CO. 



Electrical Manufacturers 



32 Park Place (Broadway Block) New York 



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



