: WIRELESS TELEGRAPHY. 
127 
allel coils of wire were placed, one at the bottom of the sea, the other 
round the lightship. It was thought that by this means signals could 
be maintained through the water; but water, especially sea water, is 
something of an electric conductor, and the energy radiated was ab¬ 
sorbed in the water in the form of “ eddy currents/' so that very little 
got on board the Lightship at all, in fact it was a failure. If this were 
the case of oscillations of only 260 a second, it would probably be 
much more so with oscillations of 260 millions a second. One, of 
course, never likes to theorise on a thing that has never been tried, 
but I do not anticipate that there would be any success. 
J. G-AVEY Esq., Principal Technical Officer, Telegraphs Depart¬ 
ment, G.P.O.—Captain Brett has given such an exhaustive and 
lucid account of both the electro-magnetic and the Marconi systems 
that I am afraid he has left but little for other speakers to say. How¬ 
ever, I have had the honor myself of conducting a large number of ex¬ 
periments on both systems on behalf of the Post Office, and perhaps I 
may usefully call attention to a few of the practical questions bearing 
on these methods of signalling. In reference to Preece’s system, I 
should wish to call attention to one fact which I do not think is gener¬ 
ally known, and it is this, that in the course of some experiments which 
I was carrying out a few years ago on opposite sides of Loch Hess, it 
occurred to me to replace the ordinary vibrating apparatus which has 
just been described, by telephones, and on connecting these to each of 
the parallel wires on opposite sides of the Loch we were able to ex¬ 
change speech, although the two wires were miles apart ; not only 
this but I distinctly heard the shouts of laughter of my colleague on 
the other side at some puerile joke which I ventured to make. An¬ 
other point is this : It is said that a length of wire is wanted on each 
side of the distance to be bridged at least equal to the distance itself, 
and that in many cases this is impracticable. There is another possi¬ 
bility, although we have not tried it on a large scale, namely, that the 
parallel wires may be replaced by large coils with numerous turns 
placed horizontally, and in that manner it would be quite possible to 
connect telegraphically an islet with the mainland where the islet itself 
was not of sufficient extent to admit of the necessary length of parallel 
wire being erected. We might place a number of coils on poles or 
otherwise, the same arrangement being made on the mainland, and it 
would be quite possible to establish communication in that way. 
There is also some hope that we may be able to arrange for a call be¬ 
cause, as Captain Brett has pointed out, that is the weak point in 
the system at present. Mr. Sidney Evershed has designed an ex¬ 
tremely ingenious form of relay in which a very fine wire is placed in 
a very powerful magnetic field, and it is possible by sending a suc¬ 
cession of induced currents through this fine wire to cause it to vibrate 
and thus to close the circuit of an ordinary electric bell. I may add 
that we are about to establish this system practically in the Bristol 
Channel, and I daresay in the course of a few months we shall be in 
a position to give you more information on the subject. 
How turning to Marconi’s system, a largo number of experiments 
