Thousands of years ago the idea of utilizing the solar rays must have suggested itself, and there are still savage tribes who know no other mode of combustion; but the scientific application has hitherto been lacking. This void this apparatus will fill up. About fifteen years ago Professor Mouchon, of Tours, began constructing such an apparatus, and his experiments have been continued by M. Pifre, who has devoted much labor and expense to realizing M. Mouchou's idea. A company has now come to his aid, and has constructed a number of apparatus of different sizes at a factory which might speedily turn out a large number of them. It is evident that in a country of uninterrupted sunshine the boiler might be heated in thirty or forty minutes. A portable apparatus could boil two and one-half quarts an hour, or, say, four gallons a day, thus supplying by distillation or ebullition six or eight men. The apparatus can be easily carried on a man's back, and on condition of water, even of the worst quality, being obtainable, good drinking and cooking water is insured. M. De Rougaumond, a young scientific writer, has just published an interesting volume on the invention. I was able yesterday to verify his statements, for I saw cider made, a pump set in motion, and coffee made--in short, the calorific action of the sun superseding that of fuel. The apparatus, no doubt, has not yet reached perfection, but as it is it would enable the soldier in India or Egypt to procure in the field good water and to cook his food rapidly. The invention is of especial importance to England just now, but even when the Egyptian question is settled the Indian troops might find it of inestimable value. Red tape should for once be disregarded, and a competent commission forthwith sent to 30 Rue d'Assas, with instructions to report immediately, for every minute saved may avoid suffering for Englishmen fighting abroad for their country. I may, of course, be mistaken, but a commission would decide, and if the apparatus is good the slightest delay in its adoption would be deplorable.--_Paris Correspondence London Times_. * * * * * HOW TO ESTABLISH A TRUE MERIDIAN. [Footnote: A paper read before the Engineers' Club of Philadelphia.] By PROFESSOR L. M. HAUPT. INTRODUCTORY. The discovery of the magnetic needle was a boon to mankind, and has been of inestimable service in guiding the mariner through trackless waters, and the explorer over desert wastes. In these, its legitimate uses, the needle has not a rival, but all efforts to apply it to the accurate determination of permanent boundary lines have proven very unsatisfactory, and have given rise to much litigation, acerbity, and even death.