The beginning of a wonderful invention

Article taken from The Navy and Army Illustrated dated 2nd March 1901

To Captain H.B. Jackson R.N., belongs the honour of first drawing the attention  of the Naval authorities to the possibilities of a wireless system of electrical communication.  In the latter part of 1895, being then in command of the "Defiance" Torpedo School at Devonport, he carried out a great number of experiments, and demonstrated that wireless communication could be established through short distances.  He worked on almost identical line to those followed by Marconi, though at first his investigations were quite independent of the young Italian scientist.  Captain Jackson's apparatus was home-made, and he was much handicapped by the want of suitable instruments.  The result he obtained were not so good as Marconi's, but he undoubtedly recognised, as perhaps no one else except Marconi had done, the direction in which to work in order to bring wireless telegraphy within an appreciable distance of practical realisation.  There were several other experimenters in the same field at the time, but the results obtained by them, though they demonstrated the possibility, fell short of indicating that the time had come for putting the matter upon a commercial basis.

Continuing ourselves to the history of events in the Navy, we find that in the spring of 1896 Captain Jackson established communications over distances up to 6,000 yards.  Signals were also satisfactorily sent between the "Defiance" and the Admiral's House at Plymouth, nearly three miles away.      By this time, however, we believe that Captain Jackson and Marconi were in communication, and to a certain extent working together.  Marconi took out his provisional patents in June 1896, and between that time and 1899 experiments were continually going on in the torpedo school with a view to ascertaining how far the invention was applicable to the Navy.

Captain Jackson's methods not proving entirely satisfactory, Mr Marconi was invited to fit up three ships for the monoeuvres of 1899 with his apparatus.  The ships selected were the "Alexandra", "Europa", and "Juno" all belonging to Sir Compton Domville's Squadron.  The experiments proved entirely satisfactory.  It will be remembered that Sir Compton Domville set out to find a convoy and escort it home in safety.  The "Europa" and "Juno" were sent out to scout ahead of the fleet, the "Europa" being fifty miles ahead of the "Juno" and the "Juno" a like distance ahead of the "Alexandra" [Admiral Domville's flagship]. On the "Europa" sighting the convoy she was able to inform the admiral of the fact over a distance of 100 miles by passing her signals through the "Juno."

This success gave a fresh impetus to the torpedo schools, and during the following year several sets of apparatus were made to Captain Jackson's specifications.  These were placed on board ships of the Channel Squadron for trial. Other sets were issued to the Reserve Squadron during 1900 manoeuvres.  Unfortunately they did not give uniform results, and in the autumn of that year, it having been decided to finally adopt a system of wireless telegraphy for the Navy, Jackson's apparatus was put on one side and Marconi's definitely accepted. Click to enlarge It is only fair, however, to Captain Jackson to say that the difficulties encountered with his apparatus apparently lay more in the matter of manufacture, and in the want of experienced operators, than in any failure of the principles involved.

Since the, wireless telegraphy has been constantly used with uniform success.  It has proved invaluable in the Channel Squadron, in China, and whenever there has been a big assemblage of ships, such as the late Naval pageant at Spithead, where ordinary signalling would have proved out of the question owing to long distances or thick weather.

The chief advantages of wireless telegraphy may be summarised as follows:-

[1] It is independent of weather, fog, or darkness.

[2] Communication is easily maintained up to fifty or sixty miles. Hence it is invaluable to the scouts of the fleet.

[3] The signals are automatically recorded.

[4] The apparatus is very portable, and can be set up anywhere in an hour or so.

It's disadvantages are:-

[1] Only one ship can signal at a time, since the receiving apparatus is not, so far, discriminating.

[2] The use of it in war-time might indicate the presence of the fleet to an enemy's scouts, who presumably will be fitted with it.

There is no doubt that the elimination of these disadvantages is only a matter of time.  Indeed, judging by Professor Fleming's letter to the Times a short time ago, Click to enlarge Mr Marconi has already overcome them to a considerable extent.  He is now able, apparently, to send or receive two distinct messages at the same time with apparatus placed only a few feet apart.  This is obtained by tuning or synchronising the sending and receiving instruments to each other.  In wireless telegraphy we are dealing with waves in the ether which are similar in every respect to those of light.  The length of these waves can be varied at will, and it is not difficult to conceive the possibility of arranging a receiver which shall respond to a certain definite wave length and that one alone.  The apparatus employed today for wireless telegraphy consists of a powerful induction coil for sending the message, a receiving  apparatus, and an aerial wire which is common to both, and can be connected to either at will. The principle upon which the whole depends is a very simple one, and has been known for some years, thanks to the researches of Hertz, Lodge, Crookes and others. These showed that a sudden and violent disturbance in the electrical equilibrium of one simple circuit was capable of producing a momentary flow of electricity in any other similar circuit in the neighbourhood.  It was further found, that if in this latter circuit a tube containing small metallic filings was introduced, the current produced a peculiar effect on these filings.  In the normal state they lay higgledy-piggledy, and made a bad path or "conductor" for the current of a small battery.  In fact , the small battery could not force a current through them.  Directly, however, the "sudden disturbance" took place in the neighbourhood , and a slight current was produced by its means, the filings arranged themselves in good metallic contact - cohered, in a word - and so formed a good path or "conductor" for the current in the battery. [These two currents and their effects must not be confounded, the one produced by the "disturbance" being of enormous velocity and minute quantity, the other produced by the cell being of considerable quantity, but of very small velocity or driving force.  It is driving power of the first that causes the metallic filings to arrange themselves so as to permit of the passage of the second.] Having got this effect, the rest is simply a question of getting some device which will record the change of state  in the "coherer" and the passage of the battery current.

We will now describe the whole apparatus connected with wireless telegraphy as simply as possible, with a view to its being intelligible to the untechnical reader.

First there is an aerial wire.  Click to enlarge This is merely a vertical insulated wire, which can be attached to the induction coil or the coherer at will.  Now imagine two stations fifty miles apart which wish to communicate.  At the sending station the aerial wire is attached to one terminal of a powerful induction coil, and at the receiving station it is attached to the coherer.  The sender presses his key, an enormously powerful current is produced by the induction coil, which rushes up the aerial wire and "charges" it so to speak. The effect of this charge upon the surrounding ether is similar to that produced by a stone thrown into a pond.  It produces waves which radiate out into space in all directions, getting wider and feebler as they get further away. Some of these radiations of course impinge upon the aerial wire of the receiving apparatus.  They set up a current in it and produce the effect already described on the coherer - that is, they convert it from a normally bad conductor into a good one.  We will this current A.

Now through the coherer is also the circuit of a single cell which works an apparatus called a relay. Click to enlarge [A relay is an electrical device for detecting a small current, and which automatically  turns on a large current to do the work required; it is, in fact, the man at the throttle-valve of the main engine.]  The current A causes the coherer to cohere and establishes B, and B works the relay, which is in circuit again with a powerful battery connected to the Morse printing machine.

This battery also works the "tapper". Call this last circuit C. So we have three distinct circuits A,B and C, by which we first detect the feeble current induced in the aerial wire by the ether waves of the sending apparatus, and then convert it into a current sufficiently strong to work the printing machine.  The tapper is a small rapidly vibrating electrically-worked hammer. Click to enlarge It's work is to keep the particles of metal filings in the coherer in constant motion by tapping the tube containing them.  This insures that the current B can only pass just at the instant an impulse A is passing through the aerial wire.  By causing the filings to decohere again, directly the impulse ceases the "dots" and "dashes" of the Morse code are clearly enunciated.