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| Apparatus for Recording Co-related Light and Sound Variations |
People may think that the use of radio microphones to record motion picture dialogue is a fairly recent innovation. During my research of the British Library Patent Archives for patents pertaining to the technical development of talking pictures, I came across the following fascinating application.
British patent No 107167 filed in 1917 by William Baldwin Vansize, a telegraph engineer of 233 Broadway, New York, USA, relates to the use of radio mics almost 50 years before they became a practical reality.
The text of the patent printed in this Newsletter has been edited to fit space available. If any members would like a photocopy of the full patent let me know and I'll send you one.
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| Apparatus for Recording Co-related Light and Sound Variations |
Click on the picture for a full size version. This invention relates to recording light and sound effects which are co-related in time and significance, and the object of the invention is to record, in moving-picture form, as on a film, photographically, certain moving, animate objects or individuals, and at the same time record on a sound-record medium any intelligible sounds, whether purely vocal or purely musical, or both, due to said objects. This is done by placing on each moving object independent means for transmitting sound through the natural medium, or by Hertzian waves, thus making each object absolutely independent of circuit connections or contacts. The apparatus employed includes telephonic wireless transmitting and recording devices.
To produce these electro-magnetic waves, each object photographed, and emitting sounds, is equipped with a portable telephonic wireless transmitting apparatus. By this it is meant to include a generator of high frequency oscillations, and a means for inflecting the oscillations with variations due to sound waves, such as a telephone transmitter of the microphone species. It is preferable to employ, as a part of this apparatus, a vacuum valve adapted for transmitting high frequency oscillations. Also there is a battery having an electro-motive force of about one hundred volts, each cell is of diminutive form and light weight of the Plante or Faure type, and fifty such cells, arranged in series, should supply about one hundred volts to the valve. The telephone transmitter is included in or associated with the circuit and supported upon the chest of the object of individual. There is a battery for heating the filament in the vacuum, and when this battery is adjusted to produce a certain degree of heat and the battery and the circuit connecting or associated with the valve is so adjusted as to cause the valve to oscillate, the variation of voice waves or sound waves due to the microphone transmitter will inflect the resulting oscillatory discharge and as these oscillations are radiated, there results a corresponding wave motion in the ether.
The antenna at the transmitting station or object, if used, is, preferably in the form of a wire of practically invisible dimensions and colour, and projects a foot or two above the object. The lower end of this antenna terminates in contacts and these contacts are adapted to engage a sheet metal floor or capacity. These contacts are preferably placed in the soles of the shoes of the individual,
In the arrangement of apparatus for recording the sounds due to the several different objects or actors, in order to make effective use of the Hertzian oscillations, a receiving and repeating stations preferably located one-quarter to one-half wave length from the transmitter, that is to say, outside the enclosure or hall and from 1200 to 2000 feet distant from the transmitters; the transmitted sound variations are there received, at the station, by a valve detector such has been described. A wire circuit, preferably a complete, metallic circuit, is extended back to the point where the sound record, in close proximity to the picture record, is to be made. The valve detector is preferably connected as a form or species of repeater or relay between the last-named circuit and the radio receiving circuit. This separate station is to provide for changes in position and movement by the moving object, the extent of movement, ordinarily, of the object being but a small part of the entire distance separating the object from the receiving station. If this provision were not made, re-tuning or re-adjustment of the apparatus carried by the object or individual, as said object moves about, might be necessary at intervals.
The accompanying drawings illustrate the invention. Figure 1 shows apparatus employed in recording the movement and vocalisation of two animate objects or individuals on a stage. Fig 2 shows in dotted, outline and detail, the transmitting apparatus carried by each individual.
In Fig 1 two objects or individuals, 15 and 16, are shown on stage; this stage has a metal or conducting surface or floor, 17, connected to earth, as shown at 25. each object, 15, 16, may be provided with a wire or antenna, 18, projecting slightly above the head. This is formed of small-gauge wire and given a colour which will not photograph effectively, the object being to avoid its representation in the picture; the antenna, 18, is connected in the circuit, 19, containing an inductance, 32, utilised as the secondary of an oscillation transformer in series with a microphone or current-varying telephone transmitter, 20, carried on the chest of the individual, so that chest vibrations are effective to control the telephonic transmission by transmitter, 20. The wire 19, is bifurcated and continued in two divisions, 21 and 22, to contacts, 23 and 24, placed in the bottom of the shoe of the individual, so as to make contact with the metal floor, 17. In addition to the circuits described here, there is carried by the individual a vacuum valve, 26, having a hot element, 27, and a cold element, 28, with an intermediate grid, 29; the hot element 27 is heated by a small dry battery, 35. A battery, 33, of say, fifty secondary elements of small size and weight (100V) , preferably one or two ounces per cell, is connected in circuit between the cold element, 28, and the hot element, 27. In this circuit is an inductance, 31, employed as a primary of an oscillation transformer, and inductively associated with the secondary coil, 32. The third or grid element, 29, is in a branch circuit with six cells of battery, 34, connected to the hot element, and including an inductance, 30, inductively associated with the coil, 31. The inductance, 30 is adjustable and , when properly adjusted, the local circuits described, including the valve, constitute a generator of high frequency oscillations.
On the stage I have shown a tripod supporting a camera, 12, with a crank handle, 13, when rotated clockwise advances the transparent film of sensitised surface upon which the photographic record is made., as is well known. The sound record medium is a tape of steel or a steel wire, like a piano string shown at 10. A supply of this wire is carried on a spool and passes around a series of pulleys including a grooved pulley, 14, on a shaft with the crank, 13, so that when the film is advanced by turning the crank, the sound-record medium, 10, is advanced with it or in predetermined relation as may be determined by varying the size of the pulleys.
At a point from one-quarter to one-half wave length distant from the stage, 17, there is erected any well-known form of wireless antenna, 40. Included in its circuit is an adjustable condenser, 41, an inductance, 42, of adjustable character, and a ground connection.
It is to be noted that the sounds emitted by the objects 15 and 16 are telephonically transmitted , by means of microphone transmitters like 20, and the high-frequency oscillations generator, carried upon the person, as shown in Fig 2, to the antenna, 40, and are transmitted to the valve, thence through the metallic circuit 51, 52, to the sound recording magnet, 11, where the sounds are recorded on the wire 10, while a visible record is photographically made upon the film of the camera, 12, in co-related order.