304 Timehri. 
Before leaving this part of the subject I should like tou draw your attention 
to the difference—and the similarity—between Hertz’s oscillator of 25 years 
ago and the transatlantic transmitting station of to-day. Jn place of Hertz’s 
simple battery for generating the primary current, we see a huge alternator 
driven by engines of 700 H.P. The induction coil of possibly 1-20 of a kilo- 
watt has been replaced by a set of transformers of 400 kilo-watts. The spark 
knobs have been replaced by specially cooled metal discs revolving at 600 
revolutions per minute. For Hertz’s capacity areas have been substituted the 
specially arranged aerial wires, huge condensers and the earth itself. Hertz’s 
oscillator would pack into a box a couple of feet square, whilst the tians- 
atlantic station with all the necessary buildings, masts, etc., occupies several 
acres of ground. 
Hertz detected the waves from his oscillator some few feet only whilst 
messages have been received from Marconi’s station at Clifden at a distance of 
5,600 miles. 
The principal disadvantages to which wireless installations are liable are 
electrical disturbances in the atmosphere, which at times interfere with the 
working of the apparatus, and occasionally—as in the case of severe thunder- 
storms—temporarily interrupt the service. Improvements are constantly 
being made though, and it is now possible to work during electrical storms 
which a year or two back would have rendered communication impossible. 
Of the advantages of Wireless Telegraphy very little need be said. Un- 
doubtedly its greatest sphere of usefulness has so far been proved to be in 
connection with shipping both from the commercial and life-saving points of 
view. The corporation of Lloyds were quick to realize its usefulness in this 
respect, and had it installed at all their more important signal stations, and I 
believe there is an appreciable difference in the insurance premiums charged 
for vessels that have installations aboard and for those that have not. 
At the International Wireless Conference, held a few years back, it was 
agreed that the emergency call from ships at sea should take precedence over 
all other wireless signals and it is now compulsory for ships and shore stations 
of whatever nationality. or with whatever wireless system installed. to comply 
with this. 
The part played by wireless in the case of the collision of the liners 
“Republic ” and “ Florida” sume two years back is no doubt well known, 
but the following statistics may prove interesting. 
During the past five years no fewer than ten thousand six hundred and 
forty persons have been rescued from ships in distress through the agency of 
wireless telegraphy, and over 4,000 lives have been saved from five vessels 
which were lost, three by sinking after collision, and two by fire. 
T personally have only twice heard the emergency call used—once while in 
charge of the installation aboard a steamer which became disabled by the 
breaking of the propeller shaft, when we were able to get into communication 
with another ship and make arrangements for towing, ete.. and once, some five 
