A pair of A.Ls.S., the first of JOSEPH HENRY (1797 - 1878) American scientist who built the first electric motor and later became first Secretary of the Smithsonian, 2pp. lg. 4to., Smithsonian Institute, Apr. 16, 1868, to the hydrographer George W. Blunt (1802-1878), in part: "...The Smithsonian Institution was the first to establish a system of telegraph signals for predicting the weather, similar to those which have since been adopted abroad. Our system which was interrupted by the war, was only partial since we had not the means to carry it on with a view to benefit Commerce...gracious cooperation of the Western Telegraph Union...We have all the appliances, with established corps of meteorological observers...and the requisite knowledge for estimating the probability of the time and intensity of the approaching commotion. The researches of the Institution for nearly 20 years have served to establish certain laws for the movement of storms...". In 1849 Henry collected the first meteorological observations via telegraph but, as noted within this letter, the network was disturbed by the Civil War. In 1868 the director of the Cincinnati Observatory established a network and issued forecasts in 1870. George W. Blunt published charts and nautical books and was engaged in marine surveys. Wear to edges, otherwise very good. Along with BENJAMIN SILLIMAN (1779-1864) American chemist and the first to distil petroleum, basing his work on the study of meteorites. A.L.S. 1p. 8vo., New Haven, Aug. 2, 1872, on American Journal of Science and Arts letterhead to a gentleman, in part: "...The 'Probabilities', of this morning were supported by an active rain at 6 o.c. which induces us to put off our visit to the Mines until Monday...Mr. 'Probabilities' is so apt to be right I never think of going against him...". Very good condition. Two pieces.