136 TRANSACTIONS OF THE ROYAL CANADIAN INSTITUTE  [VOL. XI. 
promise good results. It was at first, when the submarine bell was 
invented, attempted to use it for signalling, but it was found that it 
was not well suited for sending messages by the Morse system. No 
practicable solution was discovered till an Austro-Hungarian physicist, 
Mr. H. C. Berger, showed the way by his experiments undertaken in 
the Danube at Budapest on the transmission of longitudinal vibrations 
through water. A wire of 2 in. in diameter was set into vibrations by 
the friction of a hand-driven silk-wheel moistened with alcohol whereby 
a clear and sustained note was ‘produced, capable of being sent in dots 
and dashes of the Morse code. The wire was fastened to a plate in 
contact with the water, and was anchored at the other end to some 
fixture, but the tension of the wire was immaterial. The identical 
apparatus used by Berger was fitted in one of the United States sub- 
marine boats in 1911 and readable signals were transmitted over a range 
of two miles. Still better results were obtained with steel ribbons and 
power-driven exciters, by means of which distinct signals were trans- 
mitted over a distance of 10 miles. Recently electrically-worked oscil- 
lators, invented by Professor R. A. Fessenden, have been used instead of 
the wire ribbons and have given very promising results. This mode of 
signalling is sometimes referred to as the ‘‘submarine wireless system”’, but 
it must be distinctly understood that the transmission through the water 
takes place entirely by sound waves emanating from a diaphragm 
plate which may be part of the ship’s side. The receiver is a similar 
plate in another ship similarly connected. This appliance is now being 
developed by the Submarine Signalling Company of Boston and, 
apparently, with considerable success. 
SAFETY, SALVAGE, AND TRANSPORTATION. 
As a consequence of the numerous and serious accidents which have 
befallen submarine boats of recent years, much has been done to increase 
the safety of this craft. The hull is subdivided more minutely than 
formerly by bulkheads of sufficient strength to withstand the maximum 
water pressure. A buoy provided with telephone connection is fitted 
in the superstructure and can be sent to the surface in case of emergency, 
enabling communication to be established with the outside world. 
In some boats the men are provided with diving suits and helmets, 
enabling them to escape or to remain for a longer time in the boat when 
it is flooded. Great precautions are taken to prevent the fumes from 
the storage battery from entering the working rooms of the boat. The 
battery is in many boats placed in an entirely separate, airtight, well © 
ventilated compartment. Vessels of special type, ‘‘salvage docks’’, 
are built for the purpose of raising the boats when they have sunk to 
