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20 MARINE REVIEW. [ May 30,3: MARCONI EXPLAINS SYNTONIGC WIRELESS TELEGRAPHY. At a meeting of the Society of Arts in London on the 17th inst. Mr. G. Marconi read a paper on "Syntonic Wireless Telegraphy. He pee by explaining that his silence on the subject in the past was the result oO commercial considerations, and not from any desire to withhold his scien- tific discoveries from those able to appreciate them. After a brief mention of his original apparatus, which is now well known, he turned to the development of the syntonic system, by which it is possible to send messa- ges in such a way that they shall be taken up by one particular receiver, and no other, It is this power which gives to wireless telegraphy a com- mercial value, for as long as each receiver responded to every transmitter with its sphere of operations, there could be nothing but confusion. The original elevated straight wire, which was used as a transmitter, was a very good radiator of electrical waves, but its electrical oscillations died away with great rapidity, although they were very powerful while they lasted. The result was that it would affect receivers or resonators of con- siderably different pitch or period. The violence of its effect set them in action by one or two impulses, although those impulses did not corre- spond with their natural periods. If a radiator be used giving off much less energy at each vibration, but emitting a series of waves over an extended period, then it will only affect a resonator turned to that particu- lar frequency. It will take some time (measured in thousandths of a second) for the radiator to set up a swinging electromotive force in the receiver sufficient to break down the insulation of the coherer, and to cause a signal to be recorded. 5 Early in 1900 the vertical wire was replaced by the arrangement shown in Hig, 1. In it the radiating and resonating con- Fig.2. ductors take the form 'of a cylinder, a cylindrical earthed conductor being placed in- pONueuse? side. This form of radiating and receiving areas is very Oot efficient, as compared with anything preceding it. One necessary condition of this colL . 4 system is that the inductance 5 Orn afl of the two conductors shall be unequal, it being prefer- able that a large inductance shall' be joined to the non- earthed conductor. By using cylinders of zinc 'only 7 meters high and 1.5 meters in diameter, good signals could be sent over 50 kilo- Fug 3 COHERER meters, and these were dis- CONDENSER ' tinctly _ received, although ee 'Fug 5. other signals were passing. The closely-adjacent plates and the large capacity of the receiver cause it to be a re- sonator possessing a very decided period of its own, and so no longer apt to re- spond to frequencies which differ from its own particular period. The receiver is not shown in Fig. 1, but consists of similar cylinders, the receiving induction coil, or oscillation transformer, being placed where the spark gap is in the old apparatus. Another very successful syntonized transmitter and receiver were the outcome of a series of experiments carried out with the discharge of Ley- den jar circuits. Since the chief difficulty with the old system was that the oscillations were so very dead beat, there was associated with the radiator wire a condenser circuit, which was known to be a persistent oscillator, to set up a series of persistent oscillations in the transmitting vertical wire. An arrangement is shown in Fig. 2, consisting of a circypit containing a condenser and spark gap, and this constitutes a very per- sistent oscillator. It is sufficient to place near one of its sides a straight metal rod or good electrical radiator; the only other condition necessary for long distance transmission is that the period of oscillation of the wire or rod shall be equal to that of the nearly closed circuit. Stronger effects of radiation are obtained if the radiating conductor is partly bent round the circuit, including the condenser, so as to resemble the circuit of a transformer. An arrangement was first constructed consisting of a Leyden jar or condenser circuit, in which was included the primary of what may be called a Tesla coil, the secondary of which was connected to the earth or aerial conductor. The idea was to associate with the compound radiator a receiver tuned to the frequence of the oscillations set up in the vertical wire by the condenser circuit. The first trials were not successful, because the necessity was not recognized of attempting to tune to the same period of oscillation (of octaves) the two electrical circuits of the transmitting arrangement (these circuits being the circuit consisting of the condenser and primary of the Tesla coil or transformer), and the aerial conductor and secondary of the transformer. Unless this condition is fulfilled, the different periods of the two conductors create oscillations of a different frequency and phase in each circuit, with the result that the effects obtained are feeble and unsatisfactory on a tuned receiver. The syn- tonized transmitter is shown in Fig. 3. The period of oscillation of the vertical conductor can be increased by introducing turns, or decreased by diminishing their number, or by introducing a condenser in the series with it. The condenser in the primary circuit is constructed in such a manner as to render it possible to vary its e:ectrical capacity. The receiving station arrangements are shown in Figs. 4 and 5, Here we have a vertical conductor connected to earth through the primary of a transformer, the secondary circuit of which is joined to the coherer or detector. In order to make the tuning more marked, an adjustable condenser is placed across the coherer in Fig. 5. Now, in order to obtain the best results, it is necessary that the free period of electrical oscillations of the vertical wire primary of transformer and earth connection should T & CONDENSER Cj (3874) be in electrical resonance with the second circuit of the transformer, which includes the condenser. : a : In order that the two systems, transmitter and receiver, shall be in tune, it is necessary (if we assume-the resistance to be very small or neg- ligible) that the product of the capacity and inductance in all four circuits should be equal. Experiments have confirmed the fact thatthe receiving induction coils, having the secondary wound in one layer and at a certain distance, say two millimeters (to cause the capacity to be so small as to be negligible), have a time-period approximately equal to that of a ver- tical conductor of equal lencth. If, therefore, we are using an induction coil having a secondary forty meters long on the receiver, we should use 'a vertical wire forty meters long at both transmitting and receiving stations. By so doing we have the two circuits at the receiving station in tune with each other, and only have to adjust the capacity of the con- denser at the transmitter, which can easily be done, either by means of a condenser having movable plates that can be slid, more or less, over each other, or by adding or removing Leyden jars. If we start with a very small capacity which we gradually increase, a value of the capacity will be reached which will cause signals to be recorded on the receiver. Supposing the receiving system to be within the sphere of action of the transmitter, then the signals will be strongest when the capacity of the condenser is of a certain value. If we still increase the capacity, the signals will gradually die away; whilst if we go on increasing the capacity, and, at the same time, add inductance to the aerial, to keep it in tune with the condenser jar circuit, we are still radia- ting waves; but these do not affect the receiver. If, however, we add inductance or capacity to the wire (Fig. 5), and also to the ends of the secondary, we find ourselves able to receive messages from the transmit- ter, although we are utilizing waves of a different frequency. If two apparatus, such as shown respectively in Figs. 4 and 5, be connected to one vertical wire, evidently one will respond to vibrations of one fre- quency and the other to vibrations of another frequency. By the improvements in his apparatus, and particularly by the use of the cylinders in place of the vertical wire, Mr. Marconi has been able to render his apnaratus far more portable. He has constructed a steam motor-signaling car for use with an army. On the roof of this car, which is of the omnibus type, there is placed a cylinder, which can be lowered when traveling, its height being only six or seven meters, and by this means communication has been easily carried out with a syntonized sta- tion over a distance of fifty kilometers (thirty-one miles). A twenty-five centimeter spark induction coil,.-worked by accumulators and taking 100 watts, is used for transmitting. A strip of wire netting laid on the ground is sufficient for earth connection, even when traveling, or in place of this the electrical capacity of the boiler of the car can be used as "earth." The greatest distance yet covered by wireless telegraphy has been from the Lizard to St. 'Catherine's point, or 200 miles. The amount of energy required was not more than 150 watts. The aerial conductors con- sisted of four parallel vertical wires 1.50 meters (60 in.) apart, and forty- eight meters long, or a strip of wire netting of the same length. Evidently very considerable progress has been made in wireless telegraphy during the past few months, and the efforts of Mr. Marconi have now gone far to convert it from a random phenomenon, the action of which was only imperfectly guessed at, into a scientific process which can be controlled and utilized. THE ENGLISH ARE STILL TALKING. Mr. J. Pierpont Morgan still continues to give the English something to talk about. On the part of some it is a case of genuine hysteria. The sanest view is that taken by Syren & Shipping. It says: : "People are rapidly becoming mad in this country, and for this we have to thank Mr. Pierpont Morgan and his shipping deal. For the 999th time in our history, we are going, as Mr. Mantalini put it, to the 'deminition bow-wows.' Wilsons of Hull have chartered some ships on time to the Russians, and behold! those gas works which are not envied by the London county council come down upon the fact, and see in this a further indication of our decay as a shipping nation! The same people have discovered--after seeing the fact stated in Syren and Shipping--that the Atlantic Transport Co. and the company running the American line are also concerned in a deal with Mr. Morgan. Hence more tears and more reviling of the supineness of the British ship owner. Why the ship owner only, seeing that this same Mirgan has purchased the re- covered Duchess? Is there no chance here to throw in a word about the supineness of the daily scaremongering paper owners, who have made many shekels by grinding news out of a Fleet street coffeemill? Really this sort of thing makes one feel tired. It is almost as tiring as having to sit and listen to a man reciting bits out of Whitaker's Almanack. What is really the position? In our leader columns, a week ago, we put the position broadly. Since then Mr. J. R. Ellerman and others have placed their views before the public, through the Daily Mail. To take the vendor chairman first, he gives no direct reason for the sale which has 'stag- gered humanity.' Nor was there any need for him to do so, for money he obtained for his shareholders is reason enough in itself. The duty of a director of a company is first to those who have entrusted him with their money. Patriotism comes next. But what would patriotism do for the ship owner; what has his native country done for him so far? Mr. Eller- man roughs it out in his Daily Mail article. He suggests that our gov- ernments have successively proceeded on the footing that thirty-year-old conditions are good enough now. Ancient acts of parliament are kept on the statute book, and ship owners are made to comply with them, al- though the provisions are obsolete. It is so throughout his article, and it is indisputable that his contention is right. Nationally speaking, we do neglect our merchant marine, and to a most shameful extent. Ourselves and a few others are like one crying in the wilderness, and the wilderness is a very huge one. If this sale of the Leyland line to America will waken up our legislature to the necessity of dealing in a statesmanlike--or even sensible--way with the disabilities under which the shipping trade of this country labors, then surely a niche in some stately abbey should be Mr. eens when he goes hence. But we fear that there is no such happy chance. George Gilchrist of Belfast, Me., has laid the keel of a four-masted wooden schooner for McQueston Bros, of Boston.