124 



Mr. G-. V. MacLean on the 



reflector as possible and continued towards the oscillator. The 

 first zero reading was located at 1*5000 m. from the reflector 

 and the first maximum at 2*(>290 m. from the reflector. The 

 second zero was found to be at 4'1075 m. and the second 

 maximum at 55863 m., while the third zero was at 7*0(550 m. 

 from the reflector. We therefore have a distance o f 14790 m. 

 between the first antinode and node, 1*4785 m. between the 

 first node and second antinode, 1*4788 m. between the second 

 antinode and second node, and 1*4787 m. between the second 

 node and third antinode. This gives us a distance of 

 2*9575 m. between the first and second antinodes, and also 

 2*9575 m. between the second and third antinodes; that is to 

 say. the half wave-length is 2*9575 m., or the wave-length is 

 5*915 m. Accordingly there should be a node at *3290 m. 

 behind the reflector. No results are here recorded of the 

 observations made nearer to the oscillator than a wave length. 

 For as one approaches the oscillator within this distance, though 

 the readings show increases and decreases, yet no actual zero 

 reading was located. Moreover, in this space the phenomenon 

 above described was very strongly active and difficult to 

 overcome. The measurements tabulated below were all taken 

 in the space at least a wave-length distant from the oscillator. 

 The following are the results of nearly 500 observations. The 

 first column gives the distances of the coherer from the re- 

 flector; columns two and three give the readings on the milli- 

 amperemeter-scnle for the first maximum reading and the 

 increased reading ; while column four shows the increase in 

 the readings due to the passage of the electric waves. Five 

 measurements at least were taken at each point of observation. 

 Owing to the space all the readings occupy, only a few of 

 them are here given. The general nature of the rest of the 

 readings can be seen from the curve. 



Distances in 



metres from the 



reflector. 



First 



maximum 



reading. 



Increased 



maximum 



reading. 



The increase due to 

 the electric waves. 



0-9100 



8*050 



8125 



075 Mean 0-1035 





7 800 



7 000 



0-100 





7-DU0 



8-010 



0-1 10 





7-5.0 



7650 



100 





8-U00 



8100 



o-iuo 





8-575 



8*650 



0075 





7 70 J 



7-825 



0125 





8-1U0 



8-225 



0*125 





7-U50 



8-050 



0100 





7-9U0 



8025 



0125 



