Our readers already know of Mr. Mouchot's curious solar generators, and of the remarkable experiments that have been performed by that ingenious physicist for the purpose of turning to account that immense reservoir of heat and motive power, the sun. Mr. Abel Pifre, an engineer, has recently taken up the labors of Mr. Mouchot, and has constructed upon the same p riociples as those em ployed by his predecessor as the base of his apparatus, an insoZator, which gathers the heat of the solar rays in the focus of a mirror, and converts it in to mechanical motion. On the occasion of thefeie of the “ Union Frangaise de 1a Jeunesse,” which occurred Sunday, August 6, in the Garden of the Tuileries at Paris, there was witnessed a remarkable experiment with Mr. Pifre's latest improvements in the solar generator. There was set up on this occasion in the garden, near the large reservoir. at the foot of the Jeu de Paume stairs, ail insolator that measured 3'5 meters in diameter at the opening of the reflector. The steam obtained in the boiler carried by the reflector at its focus was utilized by a small vertical motor. of 30 kilogrammeters power, which actuated a Marinoni printing press. Although the sun was not very hot, and its radiation was interfered with by frequent clouds, the press was able to work with regularity between one and five o'clock in the afternoon, and to print on an average five hundred copies per hour of a journal specially composed for the occasion and en titled “ Soleil-Journal” (Sun Journal). This is not a revolution in the art of printing, but the result is sufficient to allow us to judge of the PRINTING A JOURNAL BY SOLAR HEAT.services that insoZators might render in latitudes submitted to a radiation at once more active and constant. W.e could not allow this splendid experiment to pass without preserving a souvenir of it. Our engraving faithfully represents the arrangements adopted. Tbe Pifre insolator is seen in the center of tt.e cut, with its large parabolic mirror; the engine actuated by it is figured at its side; while in tbe foreground to the right is seen the Marinoni press printing the journal. It seems evident to us that in hot countries the use of hemodynamics ought sometimes to prove effective and economical.—La Nature.