SYNTONIC TELEGRAPHY.
In the present state of the law in this country it appears to be necessary for a scientific man whose investigations may have any practical bearing to refrain from communicating his work to any scientific society, or publishing it in any journal until he has registered it and paid a fee to the Government under the so-called Patent Law. This unfortunate system is well calculated to prevent scientific men in general from giving any attention to practical applications, and to deter them from an attempt to make their researches useful to the community. If a scientific worker publishes in the natural way, no one has any rights in the thing published; it is given away and lies useless, for no one will care to expend capital upon a thing over which he has no effective control. In this case practical developments generally wait until some outsider steps in and either patents some slight addition or modification, or else, as sometimes happens, patents the whole thing, with some slight addition. If a scientific worker refrains from publishing and himself takes out a patent, there are innumerable troubles and possible litigation ahead of him, at least if the thing turns out at all remunerative; but the probability is that, in his otherwise occupied hands, it will not so turn out until the period of his patent right has expired.
Pending a much-to-be-desired emendation of the law, whereby the courts can take cognisance of discoveries or fundamental steps in an invention communicated to and officially dated by a responsible scientific society, and can thereafter award to the discoverer such due and moderate recompense as shall seem appropriate when a great industry has risen on the basis of that same discovery or fundamental invention—pending this much-to-be-desired modification of the law, it appears to be necessary to go through the inappropriate and repulsive form of registering a claim to an attempt at a monopoly. The instinct of the scientific worker is to publish everything, to hope that any useful aspect of it may be as quickly as possible utilised, and to trust to the instinct for fair play that he shall not be the loser when the thing becomes commercially profitable. To grant him a monopoly is to grant him a more than doubtful boon; to grant him the privilege of fighting for his monopoly is to grant him a pernicious privilege, which will sap his energy, waste his time, and destroy his power of future production.
Fig. 24
(Fig. 5 of Specification 11,575/97).—Syntonic Radiator,
adapted for sending and for receiving.
However, the author, in consultation with friends, decided that registration was, under present conditions, necessary, and, accordingly, for his attempt at syntony and other improvements in the Hertz wave method of signalling, he can refer here to certain patents taken out, in conjunction chiefly with Dr. Alexander Muirhead, his co-worker, which are numbered respectively as follows:—
Fig. 25
(Fig. 13 of Specification 11,575/97).—Diagram of connections for Syntonic Receiver; e being coherer and w a non-inductive conducting or capacity shunt, to eliminate the self-induction of the receiving instrument.
(1) 11,575 of 1897, wherein is described the general syntonic principle and the mode of prolonging the duration of the vibrations emitted by a radiator or by a receiver. This is done by adding to it electromagnetic inertia (that is, a self-induction coil) in such a way as to lessen its radiating power, converting its type of emission from something like a whip-crack into something more like that of a struck string. (Not pushing it so far as to make it like a fork, though that could be done if desired: see Journal Inst.E.E., December, 1898.) But too prolonged a duration of vibration is not desirable, for it can only be obtained at the expense of radiating power. For the most distant signalling the single pulse or whip-crack is the best, and this is what in practice has hitherto always been employed; but, with it, tuning is of course impossible. A radiator with several swings is less violent at its first impulse than is a momentary emitter; but then the lessened emitting power of a radiator is to be compensated by a correspondingly prolonged duration of vibration on the part of the receiver or absorber, thus rendering the radiator susceptible of tuning to a special similarly-tuned receiver or resonator. The tuned resonator is then to respond, not to the first impulse of the radiator, but to a rapidly worked up succession of properly timed impulses; so that at length, after an accumulation of two or three, or perhaps four, swings, the electrostatic charges in its terminal plates become sufficient to overflow and spit off into the coherer, thereby effecting its stimulation and giving the signal. A resonator not properly tuned—i.e., one tuned to some different frequency of vibration—would not be able to accumulate impulses, and hence would not respond, unless of course it were so much too near the radiator that the very first swing stimulated it sufficiently to disturb the coherer; in which case, again, there is no room for tuning. The two points to attend to for syntonic discrimination are: (a) that the receiver shall not be so near the emitter as to feel its impulses too easily, i.e., without accumulation; (b) that the properly tuned receiver shall be so arranged that it can work up and accumulate the impulses of the radiator, and before attaining its maximum swing can overflow into the coherer associated with it and thus give the signal.
Fig. 26
(Fig. 10 of Specification 11,575/97).—Interchangeable
Self-Induction Coils for signalling to different stations.
Fig. 27
(Fig. 3 of Specification 11,575/97).—Diagrammatic representation of Syntonic Radiator and Receiver. The middle spark gap h2 h3 is unnecessary, though sometimes helpful. The main charging is done by impulsive rush at the outside knobs.
Fig. 28
(Fig. 7 of Specification 11,575/97).—Syntonic
Radiator with earth connection arranged for sending.
The general appearance of a pair of signalling stations on this plan is shown in [Fig. 24], where the huts contain the sending and receiving instruments. The self-induction coil joining the two capacity-areas is better depicted in [Fig. 25], which also shows one mode of joining up the coherer to a syntonic receiver. (The galvanometer and shunt are, of course, merely typical of any kind of telegraphic instrument whatever.) [Fig. 26] indicates one form of sender with three alternative syntonising coils for speaking to three distant attuned stations. [Fig. 27] shows a radiator arranged for receiving, but illustrates another method of charging, and one frequently employed by the author, viz., the method by impulsive rush (compare Figs. [11], [12] and [19], on pp. 14 and 25 of this book). The terminals of the Ruhmkorff coil are here connected, not to the capacity-areas direct, but to a pair of knobs near the centre of gravity of each area, so that when the discharge occurs each area is suddenly charged oppositely, and the two opposite charges are left to surge into one another and set up the oscillations. This impulsive method of charging is essentially that adopted in the spherical whip-crack emitter depicted in [Fig. 19] (p. 25, ante), the two poles of the sphere having but small capacity and being joined by as thick a conductor as the equator of the sphere. But for such a radiator as is indicated in [Fig. 24] or [Fig. 27] the author commonly found that a third short spark gap in the middle was an improvement, and so, as is well known, did Prof. Righi find it, and embodied it in his well-known double-sphere double-knob emitter.
Fig. 29
(Fig. 12 of Specification 11,575/97).—Single-point Coherer, with clockwork Tapper-back operating on the projecting end of the spring clamped at P and lightly touching a needle point n.
The specification also contains figures of earth-connected forms of radiators, with or without self-induction coils, of which [Fig. 28] may be here reproduced; and likewise a modification of the point coherer depicted in [Fig. 17], on page 22 ([see Fig. 29], and also [fig. on page 27]), where the spiral wire spring is replaced by a piece of straight watch-spring, clamped at one end, adjusted by a screw at the other, and lightly touched by a needle point at its middle; a very gentle tapping back stimulus being provided in the form of a clockwork or other mechanically-driven motor grazing lightly against one end of the spring protruding beyond the clamp for the purpose.
Fig. 30
(Fig. 14 of Specification 11,575/97).—Another diagram of connections for Syntonic Receiver, with Coherer in a secondary or transformer circuit; a conducting or a capacity shunt for the telegraphic instrument being applicable as before.
Figs. 31 and 32
(Figs. 5 and 6 of Specification 18,644/97).—Modes of connecting a Coherer to one or to a pair of Syntonic Radiators so that it may feel their electrostatic disturbance.
Fig. 33
(Fig. 11 of Specification 18,644/97).—Actual connections for a Sending and Receiving Station on the plan shown in [Fig. 37]. Left-hand side shows spark sending, right-hand side shows Coherer receiving.
[Fig. 30] shows a coherer inserted in a secondary or transformer circuit, and operated inductively by the oscillations of the receiver, which are thus transformed up and raised in potential.
(2) No. 16,405, 1897, wherein are described chiefly various practical methods of decohering, by means of cams and otherwise, which are appropriate when working rapidly with automatic transmitter and siphon recorder.
(3) No. 18,644, 1897, represents different ways of connecting up a coherer to a syntonic resonator, so as to get the benefit of its overflow without interfering with the working up of the electric oscillations, e.g., Figs. [31], [32] and [33]. It also shows a plan for constantly decohering by a rapidly revolving cam a number of coherers in parallel, so that one at least is always ready to receive an impulse ([Fig. 34]). Further, it arranges to utilise the earth or a cable sheath, or other uninsulated conductor, for the purpose of conveying electric impulses to a distance (Figs. [35], [36], [37] and [38]). And next it is arranged to assist the coherer to feel the full effect of any electric jerk by shunting out the battery and galvanometer, which are necessarily in series with it, by means of a condenser of moderate capacity ([Fig. 35]), which also shows a self-induction mode of sending a stimulus along an uninsulated line. This condenser obstructs all steady currents, such as give the signal, but it transmits freely any momentary electric impulses, such as stimulate a coherer.
Fig. 34
(Fig. 1 of Specification 18,644/97).—Single-point Coherers in parallel, with successive decoherence.
Fig. 35
(Fig. 3 of Specification 18,644/97).—A self-induction method of sending jerks into a badly insulated line, and arrangement for detecting such jerks by a single-point Coherer.
Fig. 36
(Fig. 4 of Specification 18,644/97).—Another arrangement for sending jerks into a bare or badly insulated line, and connections for Coherer detection.
Fig. 37
(Fig. 10 of Specification 18,644/97).—Another mode of sending a jerk from a spark gap at j into a badly insulated cable or other conductor, which is connected at the other end to a Coherer, the circuit being completed inductively through the air by means of the areas p, p1. The dotted lines s represent the switch connection of [Fig. 33].
38
(Fig. 13 of Specification 18,644/97).—Another method of signalling through a pair of imperfect conductors, such as gas and water pipes i, without the above elevated inductive connection.
Fig. 39
(Fig. 3 of Specification 29,069/97).—Diagram of Coherer connection to Syntonic Collector, with capacity shunt for telegraphic instrument.
(4) No. 29,069, 1897. In this patent various methods of connecting up the shunting condenser, whose object it is to transmit all jerks undiluted to the coherer, are shown, all adapted to work with a syntonic resonator ([Fig. 39]). There is also shown a complete switch ([Fig. 40]) for effecting the transition from “sending” to “receiving,” exposing the coherer to the full effect of the distant radiator, and completely protecting and isolating it from its home radiator; the switch being so arranged that signalling is impossible unless the home coherer is protected. A rotating commutator is also shown, whose object is to expose the coherer to the full influence of a receiver, especially of a non-syntonic receiver or simple collector, without its being shunted or otherwise interfered with by the telegraphic apparatus; to which, however, immediately afterwards the rotating commutator connects it, and then effects the tapping back.
Connections are shown ([Fig. 41]) for a complete sending and receiving station on this plan with a syntonic radiator and resonator indicated (though not to scale). But with syntonic resonators the revolving commutator method is not found to be necessary; the sending and receiving switch, together with the closed box for protecting the coherer in an instantly accessible manner is therefore the chief feature of this diagram.
Fig. 40
(Fig. 6 of Specification 29,069/97).—Switch at a Sending and Receiving Station, to change all the connections with a protected Coherer from receiving to sending by depressing the knob l.
Fig. 41
(Fig. 7 of Specification 29,069/97).—Diagram of connections at a protected Coherer Station with Syntonic Radiator and Collector.