404 C. A. Chant — Reception of Electric Waves. 



large hall in which the experiments were made. The trans- 

 mitting wire was about l*5 ,n from the wall, the receiving wire 

 being farther out towards the middle of the room. 



1. Exploration of the Receiving Antenna as used in the Braun, 

 Siemens and Hcdske /System of Wireless Telegraphy. 



The apparatus used for these experiments was the experi- 

 mental set supplied by the Gesellschaft fur drahtlose Tele- 

 graphie, Berlin, Germany. The transmitter was described in 

 the former paper, and the receiver was arranged as shown in 

 lig. 1. The makers assert that the small set is of exactly the 

 same pattern as their large commercial apparatus. 



Antenna 



The antenna is connected to a, while to c is joined the 

 earth-plate E, in tins case a hollow metal cylinder 20 cm3 long 

 and 8 cins in diameter. The receiving transformer is composed 

 of two coils e,f the former having 5 turns and a diameter 

 of 8 cms , the latter, within the former, 5-J turns and a diameter 

 of 7 - 6 cms . At on is a very small condenser, inserted to avoid 

 shunting the coherer C. The ends n, A, are joined to the 

 polarized relay and a dry cell, not shown in the figure. The 

 lengths of the various connections are as follows : ab, 20 cm5 ; 

 cd, 20 cmb ; bed, 126 ,:nis ; gg'h, 50 cms ; m'mn, 30 cms ; coherer, 8 cms ; 

 coil /, 131 cms ; hence circuit ghmfg is 219 cm£ . 



The receiving antenna was parallel to, and directly opposite, 

 the transmitting antenna, and 2 meters from it. In the first 

 series of experiments the two antennas were kept equal and 

 both varied from 2 to 10 meters in length. Next, the trans- 

 mitting antenna was kept 6 meters long and the receiving 

 antenna varied from 2 to 6 meters ; and lastly, the transmit- 

 ting antenna was kept 4 meters long while the receiving one 

 varied from 2 to 6 meters. The readings were taken in regu- 

 lar succession from one end of the wire to the other, usually 

 at points 20 cms apart. The results of the examination are 

 shown in Table 1 and the curves of figures 2 and 3. In the 

 curves, ordinates represent magnetometer deflexions : abscissae, 

 lengths along the wire, measuring from the free end. Column 

 2 of the table, giving the position of the minima of the trans- 

 mitting antenna, is taken from the former paper. It will be 



