ELECTRICAL ADVANCE IN TPIE PAST TEN YEARS. 135 



but a few years since the late Dr. Hertz gave to the world his experi- 

 mental demonstrations of the fact that light of all kinds and from all 

 sources is really an electrical phenomenon, differing from ordinary 

 alternate- current waves only in the rate or frequency of vibrations. We 

 X^roduce electric waves of about one hundred vibrations per second for 

 alternating-current work; and in the waves of red light the rapidity is 

 as high as four hundred millions of millions of vibrations per second. 

 Hertz and others used waves of some millions per second, and showed 

 how they could transmit signals to distances without wires; these 

 invisible waves being recognized by suitable receivers. The recently 

 announced Marconi wireless telegraph is much the same thing, with 

 certain improvements in detail. It may be of limited use, but will not 

 replace telegraph lines and submarine cables. 



Our store of scientific facts has been greatly increased and our elec- 

 trical theories have been made more precise in late years; while the 

 enormous industrial expansion has furnished the means for researches 

 otherwise difficult to carry on. 



Hardly had the work of Hertz and others who followed in his foot- 

 steps been assimilated, before the truly remarkable, not to say astound- 

 ing, discovery by Professor Rontgen of what he called the X-rays pro- 

 duced a profound impression not only in the scientific world, but upon 

 the general public as well. The interest of the scientist had a different 

 basis from the popular one of disclosure of objects hidden in opaque 

 structures; for he saw in the discovery a new weapon of attack upon 

 the secrets of nature. This weapon has already proved to be so serv- 

 iceable as to show that his anticipations were not unfounded. The 

 X-rays, which became at once indispensable to surgery, are the result 

 of electrical actions in certain vacuum bulbs; and the discovery is 

 properly an electrical one. 



The rapid extension of electrical application must naturally be of 

 importance in social and economic questions. Changes in our methods 

 give rise to extension of possibilities in the lives of our people. The 

 effect of electric railways alone must be an important study for the 

 economist and social scientist. Fresh questions of law and equity arise 

 out of the conflict of the new and the old. 



The increasing importance of electrical work has had a powerful 

 effect upon the develoi)ment of many other arts. It has stimulated 

 workers in other than electrical fields to the attainment of higher stand- 

 ards, to the improvement of materials and construction, to the bringing 

 out of new products and processes in response to the demands of elec- 

 tric engineering. As a consequence, we have better and more econom- 

 ical engines, improved methods in the casting, forging, and working of 

 iron, brass, copper, and other metals. We have new alloys with special 

 properties, special grades and kinds of steel, improved methods of 

 working such substances as glass, porcelain, rubber, asbestos, mica, 

 etc. In street railways we have far better rails and rolling stock. 



