The Electro Telegraph transmits intelligence instantaneously — at least at so far as regards any distance upon the earth

Common experiments in Natural Philosophy. If two red rays from two luminous points be admitted into a dark chamber so as to fall on a white surface, and differ in their length by 0.0000258 of an inch, their intensity is doubled. So also if the difference in length be any whole-number multiple of that fraction. A multiple by 2 1/4, 3 1/4, &c., gives an intensity equal to one ray only; but a multiple by 2 1/2, 3 1/2, &c., gives the result of total darkness. In violet rays similar effects arise when the difference in length is 0.000157 of an inch; and with all other rays the results are the same — the difference varying with a uniform increase from the violet to the red. Analogous experiments in respect to sound produce analogous results.