8 REPORT —1890. 
fotit words per minute, requiring five wires for that purpose; six messages 
‘are How conveyed by one single wire, at ten times that speed, and news 
is despatched at the rate of 600 words per minute. Duplex working, 
which more than doubled the transmitting power of a submarine eable, 
was soon eclipsed by the application of Edison’s quadruplex working, 
“which has in its turn been surpassed by the multiplex system, whereby 
six messages may be sent independently, in either direction, on one wire. 
When last the British Association met in Leeds, submarine telegraphy 
had but just started into existence; thirty years later, the accomplished 
President of the Mechanical Section informed us, at our meeting at Bath, 
‘that 110,000 miles of cable had been laid by British ships, and that a 
fleet of nearly forty ships was occupied in varions oceans in maintain- 
ing existing cables and laying new ones. 
The important practical achievements by whieh most formidable 
difficulties have been surmounted, step by step, in the successive attainment 
of the marvellous results of our day, have exerted an influence upon the 
advancement, not merely of electrical science, but also of science generally 
and of its applications, fully equal to that which they have exereised upon 
the development of commerce and of the intercourse between the nations. 
of the earth. 
Thus, the laying of the earliest submarine cables, between 1851 and 
1855, led Sir W. Thomson, in conference with Sir George Stokes, to work 
out the theory of signalling in such cables, by utilising the mathematical 
results arrived at by Fourier in his investigation of the propagation of 
heat-waves. The failure of the first Atlantic cable led to the survey of the 
bottom of the Atlantic, which was the forerunner of deep-sea explorations, 
culminating in the work of the ‘ Challenger’ Expedition, and opening up 
new treasures of knowledge scarcely dreamt of when last the British 
Association met at Leeds. To the difficulties connected with the early 
attempts at submarine telegraphy, and the determination with which 
Thomson drove home the lessons learned, we owe the systematic in- 
vestigations into the causes of the variations in resistance of copper 
~conduetors, and the consequent improvements in the metallurgy of copper, 
“which led to the realisation of the high standard of purity of metal 
essential for the efficient working of telegraphic systems, and also to 
the extensive utilisation of electricity in the production of pure copper. 
The rare combination of originality in powers of research and perspicuity 
in mathematical reasoning, with inventive and constructive genius, for 
which Thomson has so long been pre-eminent, has placed at the disposal 
of the investigator of electric science, and of the practical electrician, 
instruments of measurement and record which have been of incalculable 
value, and which owe their origin to the theoretical conclusions arrived at 
by him in his researches into the conditions to be fulfilled for the attain- 
ment of practical success in the construction and employment of sub- 
marine cables. The mirror galvanometer, the quadrant electrometer, the 
. 
