SCIENCE IN THE INDUSTRIAL WORLD 



mushroom anchor at sufficient depth to be beyond the 

 destructive action of the waves. Wires were then 

 passed over the rock and submerged on both sides and 

 a telegraph plant installed, utilizing a modification of 

 the system employed by Sir William Preece in his 

 experiment. This arrangement solved the question of 

 constant communication between the lighthouse and 

 the mainland. 



EXPERIMENTS WITH "HERTZIAN WAVES " 



In 1886-7, the great discovery of Dr. Heinrich Hertz 

 that there are waves in the ether apparently identical 

 with the light waves but of much lower pitch or period, 

 called the attention of the scientific world to the possibil- 

 ity of using these vibrations for wireless telegraphy. 

 The existence of such "Hertzian waves," electro- 

 magnetic in nature, had been suggested several years 

 before by Clerk-Maxwell, but his theory had not been 

 practically demonstrated until the classic experiments 

 of Doctor Hertz. It was found that these waves were 

 comparatively tractable and that they could be dealt 

 with as if they were light waves could be reflected, re- 

 fracted, and polarized. The possibility of utilizing such 

 waves in wireless telegraphy was appreciated at once, 

 their action being the basis of all modern wireless tele- 

 graphs. 



The obstacle which opposed the use of such electro- 

 magnetic waves at a great distance was the difficulty of 

 detaching them, rather than that of sending them. But 

 in 1890-1 a "coherer" was invented by Doctor Branly 



