106 
NATURE 
are and by placing it in a strong magnetic field, the 
frequency can be enormously increased, and as many 
as a million vibrations a second may be obtained. 
Mr. Poulsen also finds that it is advantageous to have 
the anode of copper and the kathode of carbon, but 
when high currents are used the anode must be cooled 
by water running through tubes arranged for this 
purpose, 
Mr. Poulsen showed several interesting experiments, 
illustrating the delicacy of the receiving circuit, in that 
on the slightest variation of frequency the activity 
of the receiving circuit ceases. Another experiment 
with a generator the oscillation circuit of which was 
connected directly to a resonator the frequency o1 
which was in agreement with that of the generator cir- 
cuit (about one hundred and seventy thousand oscilla- 
tions per second), showed stationary oscillations with 
maximum tension at the top of the coil, and gave a 
peculiar soundless flame. As indieating the enormous 
amount of energy produced, Mr. Poulsen showed 
several experiments—lighting six incandescent lamps 
which were simply connected to a coil of wire which 
was brought near the oscillation circuit; destruction 
of a copper ring of wire when brought near, &c. 
Turning to the transmitter used by Mr. Poulsen, 
there are two things of special interest, viz. the 
coupling and the signalling. As regards the coupling, 
the usual method employed is a very loose or close 
coupling, and the tuning is very sharp in either 
case. As regards the methods of signalling, various 
arrangements may be employed, but perhaps the most 
simple is by causing the key to short circuit a resist- 
ance periodically, which resistance must be large 
enough to reduce the amplitude and be included in 
the antenna-circuit. This method reduces sparking 
and permits of quick telegraphing. One may also tele- 
graph by varying the tension of the magnetic field 
or of the feeding current, or altering the amount of 
hydrogen round the arc. 
The receiving circuit for continuous waves includes 
an oscillation circuit with the least possible damping 
and in loose connection with the antenna-circuit. 
Owing to the continuity of the waves the detector 
may be arranged in such a way that it only inter- 
mittently forms part of the circuit of oscillation. 
Hence damping is avoided which the permanent in- 
clusion of the detector would introduce. The ap- 
paratus which causes the intermittent contact is 
known as the ‘‘ Ticker,’’ and the usual material used 
for the contacts is either gold wire or German silver. 
Mr. Poulsen claims to be able to tune in practice to 
one per cent., and has received three messages simul- 
taneously without mutual interference, the difference 
of wave-length in this instance amounting to three 
per cent. i 
Under the new method of undamped continuous 
waves Mr. Poulsen has sent a message from Lyngby, 
near Copenhagen, to North Shields, a distance of 
530 miles, with a pole only 100 feet in height, for 
the expenditure of one kilowatt, and he hopes from 
this shortly to be able to get perfect communication 
across the Atlantic. 
The chief advantages of Mr. Poulsen’s system 
appear, therefore, to be:—(a) Extreme accuracy of 
tuning—thus ensuring selective signalling with no 
interference. (b) Freedom from interferences due to 
atmospheric electricity. (c) Greater efficiency due to 
accuracy of tuning and to the low potential of the 
electric surges impressed upon the aérial radiator. 
Mr. Poulsen hopes that undamped and continuous 
wave-trains may yet be adapted to wireless telephony. 
The demonstration certainly proved that a great 
advance has been made in wireless telezraphy, and 
should the methods employed be brought into regular 
commercial use, there can be little doubt that Sir 
NO. 1935, VOL. 75 | 
| NovEMBER 29, 1906 
W. H. Preece’s remark that probably the *‘* death 
Iknell’’ of spark telegraphy has been sounded will 
prove to be an accomplished fact. In the first place 
syntony will become a_ really practical affair, and 
interference troubles between neighbouring stations, 
which have to a certain degree been responsible for 
the necessity of international legislation, will disap- 
pear. Secondly, the cost of transmission will be 
diminished, as with undamped oscillations the energy 
used in transmission can be enormously diminished. 
For the same reason the effective distance over which 
messages can be transmitted will be correspondingly 
increased, and we may hope to see the real establish- 
ment of that Transatlantic communication so often 
announced and so often abandoned. J alae 
THE MARINE BIOLOGICAL ASSOCIATION 
AND INTERNATIONAL FISHERY 
INVESTIGATIONS. 
[oe CARRINGTON, President of the Board of 
Agriculture and Fisheries, paid a visit to the 
Lowestoft Laboratory of the Marine Biological Asso- 
ciation on Friday, November 23, in order to see 
the work which is being carried on at the laboratory 
in connection with the international fishery investiga- 
tions in the North Sea. The principal features of the 
work were illustrated by means of a number of speci- 
mens and charts, which were explained by Dr. Gar- 
stang, the naturalist in charge of the laboratory, 
and by his assistants. 
After being entertained at luncheon at the Royal 
Hotel by the council of the Marine Biological Asso- 
ciation, Lord Carrington, who was accompanied by 
Mr. W. E. Archer, assistant secretary to the Board, 
visited the steam trawler Huxley, which carries out 
the investigations at sea. d 
Among those present to meet Lord Carrington 
were Mr. E. Beauchamp (M.P. for Lowestoft), the 
Mayor of Lowestoft, Mr. C. Hellyer (chairman of the 
committee of the National Sea Fisheries Protection 
Association), Mr. Deputy Sayer, of London, Mr. A. B. 
Capps and Mr. J. Jackman, of Lowestoft, and the 
following members of the council of the Marine 
Biological Association :—Dr. A. E. Shipley, F.R-.S. 
(chairman), Prof. Bourne, Sir Charles _ Eliot, 
K.C.M.G., Dr. Harmer, F.R-S:, Dr: Lister; BIRSS:; 
Prof. D’Arcy. Thompson, C.B., Dr. Chalmers Mitchell, 
F.R.S.,° Mr. G. L. Alward, Mr. J. A. ravers 
(treasurer of the association), and Dr. E. J. Allen 
(secretary and director), together with the members 
of the Lowestoft staff (Dr. W. Garstang, Mr. J. O. 
Borley, Dr. W. Wallace, Mr. R. A. Todd, and Mr. 
A. E.. Hefford). 
Under the present arrangement the scheme of in- 
ternational investigations terminates in July, 1907, but 
the council. of the Marine Biological Association, in 
view of the importance of the work already accom- 
plished, is urging His Majesty’s Government to con- 
tinue similar researches upon a more permanent 
basis. In this connection the following statement of 
the views of the council has been forwarded to His 
Majesty’s Government :— 
The council of the Marine Biological Association con- 
sider that the experience of the past few years justifies 
the opinion (1) that scientific investigations carried out on 
the deep-sea fishing grounds by means of a special sea- 
going steamer have produced results of great value con- 
cerning the biology of our food-fishes; (2) that a continu- 
ance of such experimental investigations is urgently re- 
quired, in addition to the regular maintenance of market 
statistics and observations, in order to provide the exact 
knowledge necessary for the formulation of effective 
measures for the improvement of the supply of fish; and 
(3) that the advantages of international cooperation in 
