Manchester Memoirs, Vol. Ivi. (191 2), No. 13. 



XIII. On Search-Lights for the Mercantile Marine. 

 By PlENKV Wilde, D.Sc, D.C.L., F.R.S. 



{Received and read May "jtli, igi2.) 



The recent overwhehning di.sa.ster to the "Titanic" by 

 collision with an iceberg induces me to bring before the 

 Society, and indirect!)' to others interested in the applica- 

 tion of electricit}' to navigational purposes, certain causes 

 which have retarded its progress and are responsible for 

 the deplorable event which is now engaging the attention 

 and sympathy of the whole civilized world. 



Forty-six years ago I announced before the Ro}'al 

 Society the discovery that quantities of magnetism and 

 electricity indefinitely small would induce quantities of 

 these forces indefinitely great.* This discover)' was 

 embodied by me in a generator of electricit)' and 

 magnetism far surpassing in power any voltaic battery or 

 machine heretofore produced, and was named by Charles 

 Brooke, F.R.S , a " Dynmno-clectric Machine.'' ^ 



It is common knowledge that this machine in various 

 forms is utilised for producing electric light — the electro- 

 deposition of metals, the transmission of mechanical 

 power to great distances — and is an indispensable feature 

 in wireless telegraphy. 



One of my early applications of the dynamo-electric 

 machine was the projection of a beam of electric light to 

 illuminate distant objects for naval and military purposes. 



* Proc. Roy. Soc, iS66, vol. 15, p. 107. Fhi/. Tra/ts., 1S67. 

 f Pror. Roy. Soc, 1867, vol. 15, p. 409. 



Aloy 20th. igi2. 



