US794459A - Wireless telegraphy. - Google Patents

Description

PATENTED JULY 11, 1905.

w. s. 30%. WIRELESS TELEGRAPHY.

APPLICATION FILED MAY 6 1905.

uventoz Witnesses V 4:4; atkmuyl- Patented July 11, 1905.

PATENT WILLIAM STETSON HOGG, OF WASHINGTON, DISTRICT OF COLUMBIA.

WIRELESS TELEGRAPHYP SPECIFICATION forming part of Letters Patent No. 794,459, dated July 11, 1905.

Application filed May 6, 1905' Serial No. 259,153.

To all whom it may concern:

Be it known that I, WILLIAM STETsoN Hoes, lieutenant-commander United States Navy, residing at Washington, in the District of Columbia, have invented certain new and useful Improvements in Wireless Telegraphy; and I do hereby declare the following to be a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming a part of this specification, and to the letters of reference marked thereon.

This invention relates to wireless telegra phy, the objects of the invention being to provide for a more certain and accurate detection of the electric or other waves of energy transmitted through the natural media.

I have heretofore used, and disclosed the use, of sensitive material in a detector consisting of one or more contacts of selenited metal.

According to the present invention, I make use of comminuted selenited,or sulfited metals, between electrodes or circuitterminals of such form and character, that the heat efiect of the waves of energy and consequent thermo-electric-power changes occurring between the many microphonic contacts of the dissimilar thermo-electric materials, permits greater or less current-flow in a battery-circuit and the variations may be readily indicated by a sensitive galvanometer or telephone.

In order to obtain the maximum effect, the following conditions are important:

First, the material inclosed between the electrodes should be microphonic with a small current-flow; it should have'either a large plus or large minus thermo-electrio power; it should be decohering in its nature; and it should be durable so as not to be affected by heating and atmospheric oxidizing influences.

Secondly, one electrode, preferably that by which the current enters, should be at the opposite end of the thermo-electric scale from the comminuted included material; it should have a small capacity for heat, in order that its temperature mayquickly change with the oscillating currents, and for this reason may well be a line wire ora pointed wire or conductor; it should be durable and not readily afiected by heat in so far as destructibility is concerned and, should be chemically inert when heated by the current as regards the comminuted material contacting therewith, in order that the thermo-electric power between the dissimilar materials, when heated, may not be decreased by their becoming of like thermo nature.

Thirdly, the other electrode should be a good conductor and have a large capacity for heat, in order that there may be no thermoelectric change of potential at the points of contact therewith.

I am aware that detectors have been constructed embodying the thermo-electric principle and usually by the contact of dissimilar metals in the form of fine wire adapted to be heated by the oscillating currents to cause changes in current-flow, but I am not aware of any such detectors which embody the principles of the present invention.

To obtain all of the desirable conditions enumerated and secure a maximum thermoelectric-power change, is exceedingly difiicult and consequently in practice a compromise must be made. Selenium is by far the most electronegative and bismuth the most positive materials. Selenium is, as pointed out by Branly of a decohering nature when it is mixed with tellurium, both being in the form of a powder. It is, however, of great resistance even when annealed, and could hardly be made microphonic with any current. Antimony and zinc are crystalline and are also highly negative, and nickel although not negative is crystalline. In order to overcome the objection to the high resistance of selenium, and to retain its thermo-electric power, a mixture of the crystalline metals with selenium is made. This is preferably accomplished by heating them together to produce a chemical combination, whereby the resistance of the material is decreased and an effective microphonic material with weak currents is formed, especially, if a small quantity of copper is incorporated with the mixture before being heated. A high heat due" to the chemical combination is also important, as in this case, i. a. being compounded at a high temperature,

it forms a very suitable compound, not liable to be affected by any heat to which it will be subject in use.

Next to selenium, certain compounds with sulfur have thermo-electrie power and are more or less conductive, mierophonie and decohering, as for instance, artificial sulfite of copper has positive thermo-electric power and stability and the same element sulfur combined with the crystalline metals has many of the same properties. It 'is believed that tellurium compounds would act in the same manner, but I have not attempted to try every possible combination of the sulfur group with the above metals, although, it is recognized that the compounds so formed are said to conduct by electrolysis, and in such case, it is probable that after a long lapse of time and constant use the materials might lose their cfiiciency. However, this may be, if currents of a niilliampere or less are used, any material loss in efficiency would take a long time and therefore might well be disregarded. The nature of the electrolysis may be one of the principal factors in the efficient working of the material, inasmuch as my experiments and use of the material have demonstrated that when it is in contact with a material which when heated with it, combines vith it, as for instance the point of a steel needle, its decohering cfiiciency is decreased. Without attempting to theorize upon the possible formation of gaseous selenium, sulfur or other oxids and the possible changes in the resistance of these elements by heat, which changes do no doubt take place, it may be stated simply that the thermo-electric power of the heated contacts of the materials seems to be the important factor in causing the changes in the resistance to current-flow through the circuit.

The metal platinum seems to fulfil all conditions best for the electrode by which the current enters, as it has a small capacity for heat and consequently is quickly heated, especially when in the form of a line wire or pointed conductor. [t is indestructible except at the highest temperatures, is itself microphonic in contact on account of its great number of microscopic protuberances and many irregularities and it has a considerable difference of thermo-electric power as compared with selenium. However, aluminium, palladinum and metals of the platinum group, and non-metallic materials such as carbon in the form of filaments, can be used, as can also a fine copper wire inasmuch as the latter, when sulfited, forms an excellent electrode, probably on account of its great positive thermoelectric power (it and aselenide forming a most powerful thermo-electric couple.) \Vhile the materials last mentioned may be successfully employed, platinum is preferred because of its durability.

As to the third condition above referred to, a burnished, hardened steel plug has been found to fulfil all the requirements, namely, large capacity for heat, no sulfiting or oxidation, little coherence and sufficient conductivity at the points of contact of the comminuted selenited material to produce little heat, microphonic action or thermo-electric power effect, the total thermoelectric power being that between the platinum or sulfitcd copper and the selenited comminuted material with its numerous contacts. Obviously, other metallic electrodes or a carbon plug could be employed without departing from the invention.

From the foregoing discussion, the action of the detector and the probable reasons for its sensitiveness and efficiency will be readily understood, and a general description of its construction and the method of making the comminuted material will now be given.

In the accompanying drawings, Figure 1 is a sectional view through a detector embodying the present invention. Fig. 2 is a diagrammatic view of the preferred arrangement of the circuits in which the detector may be used. Fig. 3 is a similar view of a modified arrangement of the circuits.

The detector itself may be in form similar to the usual coherers and embody a cylinder A of non-conducting material such as glass or hard rubber. On the ends of the cylinder, metal caps B are cemented or secured and adapted to make contact with the terminals of a battery-circuit. A steel plug C, is in one end of the cylinder, and at the other end, the cylinder is provided with a movable plug D of any suitable metal or material with means for securing to it a fine platinum wire or wires E. The adjustment of the movable plug in or out is controlled by a tangent-screw H or other suitable adjusting means wherebya fine adjustment may be attained. As thus constructed, it is preferred that the detector be mounted in vertical position and with the comminuted material resting on the steel plug which latter is therefore at the bottom. The circuit is completed through the comminuted material by the adjustment of the platinumwire contact at the upper end. Obviously, the platinum wire may be sealed in glass with its extreme end flush with the glass and the whole attached to the movable plug by a suitable metallic cement, or the plug may be fixed and beveled and the regulation effected by turning the detector on its axis, the detector in this instance being arranged horizontally. It is also obvious that in addition to theabove old forms of construction of these parts, any other well-known form of coherer or means for regulating the relative positions of the materials therein may be used, thus the glass tube may be exhausted of air and the regulation of pressure or contact controlled by ICC IIO

the beveled plug before referred to. Nothing is claimed in the present case on the particular mechanical construction of the parts for retaining and adjusting the elements of the detector.

' The following formula for making the selenited comminuted material are some of the numerous formulae practiced by me in the production of an eflicient material and the same method of procedure may be used for the production of the sulfited material, instead of the selenited material. All proportions are by volume. One part of the finest zinc filings are mixed with one part of the finest filings of a five-cent nickel, and two parts of the finest filings of stick selenium. The mixture is then placed on porcelain and heated, as by a spiritlamp, when it is found that combination takes place with considerable heat. The residue is ground fine in a mortar and is then ready for use. Efficient material may also be formed of one part of the finest-copper filings, one part of the finest filingflof stick selenium, mixed and heated as before until combination takes place and then ground fine in themortar Efiicient material may also be formed of one part of the finest copper filings, one part of the flowers of sulfur mixed, heated and ground fine as before.

The detector can be used in any receptive electric circuit in which there is included a single cell having a voltage not over 1.3 volts, it being desirable toreduce the current-flow to aminimum sufficient to cause a microphonic action. Obviously, the result may be secured by including the detector with a shunt resistance in the circuit. Excellent results have been secured by placing the detector together with the telephone in one of the arms of a VVheatstone bridge and using a volt or millivolt meter as a galvanometer as shown, for instance, in Fig. 2 of the accompanying drawings where (0 indicates the aerial, I) the detector, c the telephone, g cl gf fixed resistance-arms of the bridge, f e the variable resistance-arm of the bridge, h the galvanometer, volt or millivolt meter, and 11 the cell or cells of the battery.

In use after the usual balancing the galvanometer is brought to zero reading when the detector is microphonic, by means of the tangent-screw of the detector and upon the receipt of electric impulses the indicator of the galvanometer fluctuates and indicates that a message is being received, thus giving notice to the operator who thereupon takes the telephone and receives the message.

In Fig. 3 of the accompanying drawings, the detector B is shown in the circuit of the battery I in parallel with the resistance D G, and the aerial A is shown with a well-understood arrangement for tuning, although it will be understood that any known or preferred method of tuning may be employed,

inasmuch as the present invention has nothing to do with this feature of the system.

The comminuted material of the detector may contain a comminuted metal not in chemical combination therewith, thus good results have been achieved with a comminuted material such as described to which has been added a small percentage of comminuted platinum, the quantity of comminuted metal or platinum added, however preferably being insuificient to cause coherence.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

l. A detector for use in wireless telegraphy embodying an electrode and comminuted conductive material in contact therewith, said electrode having a small capacity for heat and the electrodeand comminuted material being of widely-different thermo-electric power.

2. A detector for use in wireless telegraphy embodying a comminuted microphonic material, andelectrodes between which the material is included, one of said electrodes having a small capacity for heat and the other a large capacity for heat.

3. A detector for use in wireless telegraphy embodying a contact of conductive material and a comminuted microphonic conductive material in conductive relation thereto, said contact and comminuted material being of widely-different thermo-electric power.

4:. A detector for use in wireless telegraphy embodying a contact of electropositive conductive material and a microphonic conductive material in contact therewith composed of a metal combined with an electronegative element.

5. A detector for use in wireless telegraphy embodying a contact of conductive material and a comminuted microphonic conductive material in contact therwith, said contact and comminuted material being the one electropositive and the other electronegative.

6. A detector for use in wireless telegraphy embodying a contact of very small cross-sectional area and having small capacity for heat and a comminuted microphonic conductive material in conductive relation therewith, said contact and comminuted material being the one electropositive and the other electronegative.

7. A detector for use in wireless telegraphy embodying a contact of very small cross-sectional area and acomminuted material in conductive relation thereto formed of a metal combined with selenium.

8. A detector for use in wireless telegraphy embodying comminuted selenited conductive material included between electrodes one of which has a small capacity for heat and the other a large capacity for heat.

9. In wireless telegraphy the combination at the receiving-station, of a circuit arrange- IIO ment embodying a \Vheatstone bridge, a detector and telephone in one arm of said bridge and balanced by the variable-resistance arm and a circuit from the aerial including the detector.

1(). In Wireless telegraphy a receiving-station equipment embodying a Vl heatstone bridge, an adjustable detector and a telephone in one arm of said bridge and balanced by the 'ariablea'esistance arm and a circuit from the aerial including the detector. I

11. A detector for use in Wireless telegraphy embodying a comminuted material formed of chemically-combined metal and electronegative material.

12. A detector for use in wireless telegraphy embodying acomminuted material formed of chemically-combined metal and selenium.

13. A detector for use in Wireless telegraphy, embodyingacomminuted material formed by 20 a mechanical mixture of acomminuted metal and a comminuted metal chemically combined with an electronegative material.

14. A detector for use in Wireless telegraphy embodying a comminuted material formed of 5 comminuted selenide of a metal mechanically mixed with comminuted platinum.

WILLIAM STETSON HOGG.

Vitnesses:

THOMAS DURANT, ALEXANDER S. STEWART.

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