An article in the Scientific American of Feb. 12th asserts that M. Niepce de St. Victor, has presented the third memoir on Heliotive preparations, that the sunlight possessed the strongest operative power from half-past nine oclock till eleven A. M. Half an hour before or half an hour after the sun enters the meridian the operative power is much decreased, but continues steady until three oclock, in the months of June, July, August and September. Now, I could not reconcile this phenomenon with any of the popular theories upon light, and therefore sought to account for it in some other source, and I will proceed to lay belore you what I consider to be the true cause. I suppose the sun to be composed of pure electricity—a cold invisible body—its electricity travelling to the earth in never-ceasing streams, striking our atmosphere by friction, thereby producing light and heat. I believe this to be the only theory that can explain this and other phenomena equally cn-rious, which, until the discovery of M. Da-guerre, escaped observation. We will suppose S, in the accompanying engraving to represent the sun, and O the rays of light or electricity issuing therefrom, striking upon the atmosphere, M, and the globe,