US753508A - Thomas z - Google Patents

Description

No. 753,508. 1 PATENTBD MAR-1, 1904. T. Z. MILLARD & P. H. ALMER. LIGHT MEASURING INSTRUMENT.

AHFLIGATION FILED MAB-. 23. 19034 HO MODEL.

24 5 in e 55 :25

UNITED ST TES Patented March 1, 1904.

PATENT: OFFICE. Y-

THOMAS Z. MILLARD, OF OTTUMWA, AND PHIL HAROLD PALMER, OF BLOOMFIELD, IOWA; SAID MILLARD ASSIGNOR TO SAID PALMER.

LIGHT-MEASURING INSTRUMENT.

SPEGIFICATLON forming part of Letters Patent No. 758,508, dated March 1, 1904.

Application and March 23,1903.

- photometer that will directly indicate the in-- tensity of light transmitted to it and also to directly indicate the relation of the intensity of light emitted from an electric lamp to the current consumed by said lamp. vVlre attain this by applying a retarding force or retarding forces to the rotation of the vane in an ordinary radiometer in such a manner that the vane instead of revolving completely around its axis will move through an angle the greatness of which depends upon the intensity of light striking the vane. Thus thefintensity of said light is directly indicated upon ascale calibrated along said angle.

The accompanying drawing shows a vertical section of the instrument by which we attain the foregoing objects I v The instrument consists of an air-tight bulb G, around which is fastened a coil of insulated wire P P, and on the inside of the bulb G is a very light vane consisting of an absol-bent of light.D and a reflector of light C, attached one to each end of a magnetic needle A, which is attached perpendicularly to a spindle B, which rests in sockets wt and n. The air is exhausted from the bulb to a degree at which the vane will most readily move under the force of light. Also included with the instrument is the adjustable support consisting of a base R, on which there is an adjustable clamp S, which clamps to a semicirculai' rod T, which supports the bulb G and coil P P. i

The end E of the magnetic needle A is made heavier than the other end, so that the vane Serial No. 149,218. (Ht model.)

will seek acertain position of equilibrium when the instrument is supported inan in-.

clined position and the vane is acted upon by ment by means of clamp S. so that the spindle B is vertical, the force of gravity will not retard the rotation of the vane, and the force of magnetism from the current in the coil will act alone as a retarding force against the force of light on the vane. Then by passing the current of an electric lamp whose light shines against the vane of the instrument through the coil the relation of the intensity of light emitted by the lamp to its current consumption will be indicated by the position of the vane. Scales may be calibrated upon the bulb at V and V. x

Between the source of light to be measured and the instrument-is interposed an alum-cell -which hinders the obscure heat-rays which may'radiate from the source of light from reaching the instrument. As heat has. a tendency to rotate the vane, temperature corrections maybe made by the adjustment of inclination of instrument by means of clamps.

We are aware that the intensity of light has been measured by the speed of rotation of the vanes in radiometers; but to the best ofour knowledge we are the first to apply the prin- I ciple of repulsionand attractionof light on reflectors and absorbents of light in such 21- 5 manner that the intensity of light will be indicated directly with success, making a. direct reading photometer and efficiency-indicator.

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to secure by Letters Patent, is

The combination in a radiometer of a vane of 5 be What we claim as our invention, and desire In testimony whereof we have signed our names to this specification in the presence of IO two subscribing witnesses.

THOMAS Z.-MILLARD.

PHIL HAROLD PALMER:

which amagnetic needle made with one end avier than the other is a part, a coil of insulated Wire the plane of which coincides with Witnesses: the axis of the vane and an ad ustable sup- W. S. CHESINAN, port, all substantially as shown.

B. W. SCOTT. v

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