1911 five
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“DAILY MIRROR” W.T. DEMONSTRATION.
This demonstration, which was initiated by the “Daily Mirror,” took place at Ramsgate, on
_ September 27th, 1911, and was attended by representatives froin the Admiralty, War Office,
Trinity Honse, and many other bodie-.
The inventor of the system, Mr. Sharman, explained briefly his method of communication,
after which he carried out wireless telegraphy communication between the lecture reom and a
boat moored out in the bay at a distance of about a mile from the shore, using a power of about
6 watts. The attempt to establish wireless telephony communication with the same boat was not
successful, though Mr. Sharman stated that he had never previously experienced any difficulty.
The invention is based on the following principle :—
If a current he caused to flow between two earthed plates separated, say, about 100 yards
from each other, the current will not, if of sufficient density, take the most direct pith between
the two plates, but will spread out and take up a path similar to that taken by the lines of force
between the poles of a horse-shoe magnet; if, now, two similar earthed plates, about the same
distance apart as in the case of the first pair, be placed in this field of ‘ current leakaye,” and a
device for detecting minute electric currents be placed in the circuit joiniig them, then some of
the leakage current will pass through this circuit by these earth plates and cause the receiving
device to respond.
In practice it has only been possible up to now to obtain communication in this manner over
a distance between the pairs of earth plates of about five times the distance separating the two
earth plates of a pair, but this invention claimed that, under certain conditions, and with the
instruments designed by the inventor, the available range had been increased by four times that
formerly obtained.
The system was worked as follows :—
On the shore there were two earthed plates separated about 100 yards apart, from which
two insulated wires were led, and connected to a specially constructed auto-transformer, the
winding of which was rather similar to the primary of an induction coil, but having many more
turns of wire, in such a manner that the transformer gave a step down voltage to the line wires,
the ends of the cvil being connected through a morse key and hammer make and break to six dry
cells connected in series.
For transmitting, the hammer make and break was operated in the usual manner, thus
inducing high voltages in the transformer and stepping down the induced voltage between the
earth plates, with a consequent rise of current capacity output, thereby obtaining proportionately
high momentary current density in the line circuit and between the earth plates.
For telephony, the hammer make and break was replaced by a microphone transmitter.
In order to “ receive” the ouly alteration made was to switch a telephone receiver having a
resistance of } ohm into the line circuit.
In the boat were placed exactly similar devices and instruments as on shore, one earth plate
being hung over from the boat, the other from a buoy towed about 100 yards astern.
The greatest range for a given base length is obtained when communication takes place
through salt or brackish water, the range for telegraphy under these circumstances being about
20 times the base length when the bases are squarely opposite one another, about twice the base
length when the bases are in line with one another, and no communication at all when the bases
are at rivbt angles and opposite to one another (forming letter “T”); for telephonic com-
munication the distanees are about one third those for telegraphic communication ; when com-
munication is through land the ranges are about half those obtained through sea, though this
varies with the nature of the soil.
In its present state the system is entirely useless for Service purposes, principally due to its
extremely <lirectional effect. It is thought that, with larger power and in some way overcoming
the present directive effect, the invention might be made of some use, but it is not proposed that
“* Vernon” should take up the matter experimentally.
OL
The difficulty against increasing the range for telephony by means of using larger power is
due to the usual trouble with the microphone transmitter, when the current passed through it is
increased beyond a certain maximum.
CLIFDEN W.T. STATION,
(Abstract of report by the G.P.O. Inspector of W.T. on the working of Clifden, during
December 1910 to January 1911, as observed at Skegness W.T. Station.)
Average per
Summary, diem.
Total number of public radio-telegrams from Clifden in 29 days - 1,406 - 48
Number of words in above telegrams - - - - 10,718 - 370
Estimate,
*Number of telegrams from Glace Bay 23 days - - ~ 1,352 - 59
Number of words in press messages from Clifden, 29 days - - 17,453 - 603
Number of Service messages from Clifden, 29 days - - - 473 - 16
2. In my opinion, the communication between Clifden and Glace Bay is good only under
favourable conditions. The time of year at which these observations were inade is the most favour-
able for wireless telegraphy, i.e, short days and few atinospheric disturbances.
3. Under unfavourable conditions the communication is likely to be very difficult as now arranged
over the circuit,
4. I do not think there is much in transatlantic wireless telegraphy under present conditions as
a commercial undertaking.
5. I think communication over 2,500 :iles is quite good enongh, however, for places where there
is but little tvaffic, or in any case where it is strategically desirable. I should call it very much
slower, but quite as reliable, as cables. A message miy be delayed many hours owing to local
conditions, but it is practically certain to get threugh in the end.
6. Other localities in the world might, perhaps, give better technical pos -ibilities,
7, After conversations with the onerators, | think a speed of ten words per minute in plain
language could be maintained between Clifden and Glace Bay, under normal conditions, for 12 hours
per diem each way, including repetitions, &c.
8. The best speed dues not exced 20 words per minute.
Revort on Cuirpen W.T. Srarions.
(By Capt. C. G. Crawley, R.M.A., H.M.LS. “ Defiance,” date | 29/5/11.)
ro106e The following are the changes in the station itself since last year’s report, August
Transmitting Arrangements.
Spark Gap.—.A new disc spark gap was, in use. This disc has 12 studs, and is run at 1,600
revolutions, and is mechanically more efficient than the older pattern,
Blower,—A. blower is now used on the spark. The air from the fan motor passes through a
cylindrical metal reservoir on its way to the gap. This arrangement steadies tie air pressure on the
spark, and assists in keeping the air cool,
Mr. Marconi stated that the chief use of the blower was to “ quench ” the spark, not to prevent
arcing, and that since it was fitted, one wave only—the wave to which the primary and aerial are
tun ed—waus transmitted.
Traffic.—The total traffic sent and received averages 20,000 words per week, and an increase
is not desired just at present, owing to the difficulty of fitting in experimental work.
Inker,—An iuker recorder is used. It is placed next the sending Morse key, and is used asin
Fig. 1, being operated by a “neon ” tube connected as a cohcrer in a circuil influenced by the aerial.
It thus has the advantage of recording the signals made by the spark, not necessarily by the
key.
Earth Gap.—The gap in the earth lead of the aerial is shorted, when sending, by a solenoid
switch, worked off contacts on the send receive switch in the receiving room. This is done as the
gap is sometimes shorted permanently by the metal fusing,
* Observations only obtained on 23 days, and then only from Clifden’s acknowledgments, not by nearing Glace
Bay itself, : :
D4
32
Fie. 1.
1
| Sf fact Gerad
Meéeor Trbe
200 Volis
frelay to
work Inker
Receiving Arrangements.
A balanced circuit is still uscd to reduce atmospherics. It certainly does reduce atmospherics
more than signals, but it was not possible to obtain a conclusive test of its efficiency on the
22nd May, as the atmospherics were not strong enough. It was said that the oscillation valve
is suitable for the reduction of atmospherics owing to the limiting value of the current through
the valve. Carbon filament valves were in use, but it was said that the tungsten ones were
also often used.
Experiments.
(a) Duplex Working —Mr. Marconi demonstrated the practibility of sending full power from
the Clifden Station on a 15,750-feot wave at the same time as signals were being received from
Glace Bay at a station 8 miles from Clifden on a 21,000-foot wave.
This latter station was at Letterfrack, 8 miles N. 10° E. of Clifden Station, with no high land
intervening in a straight line between the stations.
The receiving circuit is shown in Fig. 2, A second low directional aerial for Clifden joined
to the rejector in prolongation of the one shown, and exactly similar to it, was also tried and
appeared to improve the effect.
The vertical plane through these low aerials is, roughly, at right angles to that through the
high aerial.
Receiving Circuit at Letterfrack :—
Glace Bay, 3,000 miles away, sends 21,000-foot wave.
Clifden, same power, 8 miles away, sends 15,750-foot wave.
Letterfrack receives Glace Bay ; cuts out Clifden.
Fig. 2.
|A
BS |
at
a
ees ae
- -§60865-- 1!
rit
GS
A=Single wire, 6,000 feet long from top of hill 1,280 feet above station, tuned to 21,000-foot wave,
directional for Glace Bay. B = Rejector for 15,750-foot wave. C = Rejector for 15,750-foot wave. D = Tuned
to 21,000-foot wave. E = Single wire 5,000 feet, long, 30 feet above station, tuned to 21,000-foot wave, directional
for Clifden. F = Conductive earth in pond. G = To valve circuit,
TYPICAL QUENCHED GAP.
REFERENCE.
COPPER SPARK RINGS.
amolalol>
BRASS HOLDER.
WOODITE COMPRESSION RING.
BOLTS FOR ADJUSTING GAP.
SCREWS FOR GAUGING GAP.
GAUGE FOR SETTING GAP.
PERTINAX TUBE.
zlelrlale|zio
COPPER TUBE.
TERMINALS FOR CONNECTING UP GAPS.
SCREWS FOR CONNECTING TO RESISTANCES.
PLUG FOR FILLING WITH HYDROGEN.
COOLING AIR BLAST.
LEAD PLUG,
WAVEMETER.
prtee du
PLAN.
REFERENCE.
A| FIXED VANES FOR CONDENSER
Bi MOVING VANES FOR CONDENSER.(VARIABLE) |F THERMO- GALVANOMETER.
.C’ GLASS CONTAINER FOR CONDENSER, G'_THERMO- JUNCTION (IN COVER).
H| MUTUAL FOR USE WHEN MEASURING
if
D) DETACHABLE HANDLE FOR
WORKING CONDENSER . WAVES NOT INSIDE SAFETY SCREEN.
£| INDUCTANCE ENGAGING CONTACTS | DRAWER FOR REPAIR OUTFIT.
_'NSIDE OF BRASS BOX. J | SPARE THERMO-JUNGTION (IN BOX). ¥ Oey
L| FIXED VANE
K| HANDLES FOR LIFTING WAVEMETER.
CONDENSERS. Mj SPRING CLIPS TO RECEIVE STAND
—— —S
wu
The arrangement works as follows :-—
The high aerial is tuned to and receives (lace Bay because it is high enough and is directional.
The high aerial also receives Clifden very strongly because it is close and high, although it is not
in tune and is not directional. Its rejector, however, tends to prevent it oscillating with a
15,750-foot wave, and the principal effect of Clifden is to oscillate the aerial at its natural
frequency, i.e. that of a 21,000-foot wave.
The low aerial is tuned to but cannot receive Glace Bay because it is not high enough and
is not directional. The low aerial receives Clifden very strongly because it is close and directional,
although it is not in tune and is not high. Its rejector acts as in the high aevial.
It can therefore be arranged that the effects of Clifden on each aerial are the same and balance
each other so as to produce no effect on the intermediate receiving circuit, which, influenced by
the high aerial, receives Glace Bay.
Remarks.—In this cxperiment, before Clifden sent at all, the strength of signals from Glace
Bay, at Letterfrack, was not more than 4, so that the results were a good test of the efficiency of
the arrangement, because with a really good receiving aerial, such as that at Clifden, the strength
would have been 8, and the fact of its being a good receiving aerial would not have influenced the
effect of Clifden, as the increased strength of Clifden could have been cancelled by inercasing the
efficiency of the low aerial, which, in any case, would not be affected by Glace Bay.
This point was not mentioned by Mr. Marconi, which tends to show that he considered the
efficiency of the arrangement was sufficiently apparent to render unnecessary any remarks as to
how it would be improved in practice.
In adjusting the circuit to completely cut out Clifden, the streugth of Glace Bay was reduced
from 5 to 3.
The value of the test of course depended on whether Clifden was using full power, and
Mr, Marconi stated that she was doing so.
Mr. Marconi further stated that these were ouly preliminary experiments, and that he thought
that very soon simultaneous transmission and reception on waves much closer together than those
shown would be practicable, and that he intended to push on at once with this duplex system and’
obtain the necessary rights over land, &c., and also the licence required for a receiving station near
Clifden, at Letterfrack, or other convenient place.
It was apparent that the aerials and temporary station at Letterfrack had only very recently
been rigged up and the results of these preliminary tests would appear to fully justify Mr. Marconi’s
optimism on the success of the aed
Mr. Marconi suggested that the arrangement might be useful in ships for cutting out
interference. ‘That is to say, a ship with a high acrial and a low directional aerial might receive
on the high one and direct her low one on the interference so as to balanve the effect of the
interference on the high aerial by its effect on the low one. This, however, does not seem very
practical, as to cut out interference would entail manoeuvring the ship for that purpose, and would
even then be extremely difficult, as an efficient dircctional acrial cannot be rigged in a ship, and
the wave-length and the direction of the interference may be difficult to discover, and indeed this
latter may be continually altering.
(b) Mercury Oscillation Valve.—This valve, Fig. 3, is said to le far more sensitive than the
Fleming valve, and when tried during the visit, signals from Glace Bay, which were 8 on the
Fleming valve, were 11 on this one.
It was said that as the platinum point must protrude only a minute amount from the mercury
the surface of the lattcr must remain constant, and that accordingly at present there seems little
chance of adapting the valve to ship use.
The valve is a rectifier, a small arc being formed in mercury vapour between the platinum
oint and the metal electrode which forms the anode for the stream of ions. ‘The are takes place
in a magnetic field, which was provided by electro-magnets ontside.
The valve is connected in the usual circuit.
Mr. Marconi said tiey were prepared to supply one to the Admiralty for trial, and would
like to send a representative to fit it up.
«
Fig. 3.
A = Exhausted glass bulb. D = Metal plate.
B = Metal plate. E = Pt. point.
C = He reservoir. F = Hg.
ve LlLQsu—z
—
a
B34
(c) Eintloven Galvanometer.—The galvanometer was connected up, the filament being in
series with the oscillation valve, so that signals from Glace Bay could be heard, and at the same
time read by the deflection of the shadow on the screen.
This arrangement had been fitted up for the occasion, as the work at the station is done by
sound only.
The disadvantage of the galvanometer, due to the fact that the atmospheric difficulty is
greater with the galvanometer than with the telephones, was referred to in last year’s report, and
has not yet been overcome, but is thought to be by no means insuperable,
A few very good photograpbic films of signals received from Glace Bay by the galvanometer
were shown.
(d) Rectifier—Mercury-carbon rectifiers, supplicd by Westinghouse Cooper Hewitt Company,
were being tried to save expense by utilising the alternators for charging the cells.
It was thought this would prove practicable.
(e) Ship’s System.—No further experiments with the sparkless system have been carried out,
nor is it apparently intended to do so, at any rate, just at present.
Mr. Marconi said that he had no experience with the quenched spark system, but that he
thought it might prove efficient for ships, &c., though it was not adaptable to high power.
He also said that kites might be used with advantage in ships.
it would appear that the Marconi Company have made no material advance in ship installations
for some time, and the fact that the spark gap is enclosed was referred to as one of the latest
improvements.
(£) Other Stations.—Coltano is expected to be working by the autumn.
The agreement by which Marconi Company takes over the [iffel Tower station and builds
a high-power station at S. Lazaar is apparently about to be signed.
(III.) Points, already referred to, that Mr. Marconi wished to be brought forward :—
(1) The question of increasing Clifden’s wave to about 24,000 feet.
(2) The fact that he intended to try to acquire land and a licence for a receiving
station near Clifden.
(3) The fact that the Company were prepared to supply a mercury oscillation
valve to the Admiralty for trial and would like their representative to fit
1f up.
FOREIGN W.T.
(Abstracted from Official Reports received in “ Vernon.”)
TRANCE.
Fiffel Tower seems able to change her note at will. Confirmation is required. Usual wave
6,500 feet, 7,560 also heard. The Biffel Tower is also reported to have been in communication
with Glace Bay. Bizerta was heard on wave-lengths of 5,000 feet and 2,500 feet.
It is intended to instal many small stations in Belgian and French Congo.
The French Army has eleven sets on motor cars, and each army corps will shortly have a
motor car 250-kilometre set.
“ W.T. Lighthouses” are being fitted. The sets are to send automatically the respective
call-sign at definite intervals, It is understood that this is intended primarily for the benefit of
ships fitted with the Bellini Tosi directive system as an aid to navigation,
Only three public coast stations are working in France, compared with 19 in England, 16 in
Germany. (September [911) SFR (Paris), using U tune, heard communicating with Lepel
experimental station at Slough.
GERMANY.
Experiments with the high note mentioned in 1910 continue to occupy German ships
and stations. The principal wave-length noted is 6,500, which completely swamps our ‘« W ”
tune. Poulsen sets are reported to be fitted to all German battleships. These have an
interrupter in the transmitting cireuit, which night produce the peculiar high note. Men-of-war
haye call signs such as WX XW, ZrPZ, &c.
Three classes of code are in use: single letters, three letter, and 5 to 10 letter; the last
apparently a transposed alphabet, like the Aldershot cypher.
The German Government are building two stations in German S.W. Africa at Luederitz
Bay and Swakopmund to be ready in February. These are to communicate with Kamerun and
Monrovia, whence there is direct cable communication with Germany. ‘These stations should be
heard by the Cape squadron.
Greecr, ATHENS W.T. SraTion.
Masts.—Four 50-foot masts at the corners of a square of side about 100 yards, and a central
150-foot mast.
Aerials.—(1) Small aerial of four wires, one to the top of each short mast, radiating from the
top of the central mast ; used for the 300 and 600 metre waves.
(2) Large aerial, umbrella type, four sections of cight wires, in the form of a Maltese cross,
about 6 feet lower than the small aerial, with a 32-foot feeder ; used for the 1,200-metre wave.
“ Appendix Plate IX.
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NEW RIGGING INSULATOR.
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Wh,
REFERENCE.
STEEL CYLINDER.
CiT/O;}UMIig\jo|al|yp
SCREWED END PIECE.
HOLES FOR PIN SPANNER.
PORCELAIN.
LEAD WASHERS.
STEEL BOLT.
PLATE WASHER
SCREW SHACKLE.
PIN.
Earth consista of 132 galvanised iron plates buried vertically in ground to the depth of
2 metres, forming a circle, and joined to instrument room by copper wire.
W.!'. Offce.—The transmitting room is not screened,
The receiving room is not padded, but is fairly silent.
Transmitting Apparatus.—Power is supplied by a 10 h.p, Gardner oil engine, Otto cycle,
driving a 10-kw. eight-pole rotary, which supplies 400 volts D.C. for lighting, blower, &e., and
A.C. 100 to 300 volts at 100 cycles.
The insulated copper disc, 1 foot in diameter, of the revolving spark gap, fitted with teeth, is
secured fo the shaft of the rotary.
The fixed spark plugs are of 3 inch copper rod.
The note is clear, but not very high, about 200 cycles.
The condensers, glass plates in oil, can be arranged for capacities of 1,200, 600, or 300 jars.
The mutual consists of one turn; adjustment for tuning being obtained on a copper helix,
7 inches diameter, 1 inch pitch, about 4 feet away from the mutual coil.
The coupling was said to be 9 per cent.
The main transformer can be adjusted to suit 1,200, 600, ov 300 metre waves. The current
is first passed through a small 3 to | step-up transformer. Both transformers are oil cooled.
Protecting coils are fitted,
No impedance coil is used.
No part of the H.T. circuit is earthed.
The magnetic key forms a single pole break in the H1.'. cireuit, is similar to the Clifden key,
and is fitted with a powerful blower.
No safety gear is fitted, and few of the leads are lead cased.
A break in the E, lead, consisting of two discs, separated by a thin dise of mica, round the
edges of which the spark takes place, forms the operating device
Receiving Apparatus,—The usual Marconi receiving circuit was fitted. AM.D., with one
magnet only, was used.
An old Marconi box was also provided, and it was intended to purchase a “ valve receiver.”
Distance.—The 1,200-metre wave had so far failed hopelessly, and never done anything near
the distance expected, i.e., 1,000 kilometres by day. The failure was attributed to the “ earth.”
The distances of the other waves were satisfactory.
Staff,— Oue officer, three mechanicians, six operators.