AS a “manual for the general practice of photometry, with especial reference to the photometry of arc and incandescent lamps,” this work will be found useful. Most of the descriptions of photometers ...

If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the ...

IF we place the “grease spot” screen between two sources of light, situated at A and B, whose intensities are I and I′ respectively, and if C be the position of the screen for which the spot ...