444 PROCEEDINGS OF 



elaborated his beautiful and original theory of the formation of dew, and supported 

 it by many well-devised and conclusive experiments. The series of hourly obser- 

 vations, by Professor Snell and Capt. Mordecai, are well known ; and the efforts of 

 New York and Pennsylvania, of the medical department of the army, and its pre- 

 sent enlightened head, Dr. Lavvaon, have much advanced this branch of science. 

 The interesting question, does our climate change, seems to be answered thus far 

 in (he negative, by registers kept in Massachussetts and New York. There are 

 two rival theories of storms. That of Redfield, of a rotary motion of a wide co- 

 lumn of air, combined with a progressive motion in a curved line. Espy builds on 

 the law of physics, e.xamines the action of an upmoving column of air, ahowa 

 the causes of its motion and the results, and then deduces his most beautiful theory 

 of rain and of land and water-spouts. This he puts to the test of observation ; and 

 in the inward motion of wind towards the centre of storms, finds a striking verifi- 

 cation of his theory. This theory is also sustained by the overthrow or injury, in 

 the recent tornado at Natchez, of the houses whoso doors and windows were 

 closed, whilst those which were open mostly escaped unhurt. Mr. Espy must 

 be considered, not only here, but throughout the world, as the head of this branch 

 of science. This subject has been greatly advanced by Professor Loomis, whose 

 paper has been pronounced, by the highest authority, to be the best specimen of in- 

 ductive reasoning, which meteorology has produced. The most recent and highly 

 raluable meteorological works of Dr. Samuel Forry are much esteemed. Many 

 important discoveries in pneumatics were made by Dr. Franklin and Count Rum- 

 ford, and the air pump was also greatly improved by Dr. Prince, of Salem. 



Chemistry, in all its departments, has been successfully pursued among us. 

 Dana, Draper, Ellet, Emmet, Hare, the Mitchels, Silliman, and Torrey, are well 

 known as chemical philosophers; and Booth, Boye, Chilton, Keating, Mather, R. 

 Rogers, Seybert, Shepherd, and Vanuxen, as analysis; and F. Bache, Webster, 

 Greene, Mitchell, Silliman, and Hare, as authors. In my native town of Northum. 

 berland, Pennsylvania, resided two adopted citizens, most eminent as chemists 

 and philosophers. Priestly and Cooper. The latter, who was one of my own pre- 

 ceplors, was greatly distinguished as a writer, scholar, jurist, and physician, as 

 well as a chemist. Priestly, although I do not concur in his peculiar views of 

 theology, was certainly one of the most able and learned of ecclesiastical writers, 

 and possessed also a mind most vigorous and original. His discoveries in pneuma- 

 tic chemistry have exceeded those of any other philosopher. He discovered vital 

 air, many new acids, chemical substances, paints, and dyes. He separated nitrous 

 and oxygenous airs, and first exhibited acida and alkalies in a gaseous form. He 

 ascertained that air could be purified by the process of vegetation, and that light 

 evolved pure air from vegetables. He detected the powerful action of oxygenous 

 air upon the blood, and first pointed out the true theory of respiration. The 

 endiometer, a most curious instrument for fixing the purity of air, by measuring 

 the proportion of oxygen, was discovered by Dr. Priestly. He lived and died in 

 my native town, universally beloved as a man and greatly admired as a philosopher. 

 Chemistry has actively advanced among us during the present century. Hare's 

 compound blow-pipe came from his hand so perfect, in 1802, that all succeeding 

 attempts of Dr. Clark, of England, and of all others, in Europe and America, to 

 improve upon it or go beyond the effects produced, have wholly failed. His mode of 

 mixing oxygen and hydrogen gases, the instant before burning them, was at once 

 aimple, effective, and safe. The most refractory metallic and mineral aubstancea 



