282 JOSEPH HENRY, LL.D. 



Elected in the spring, and not entering upon his 

 work till autumn, he spent the intervening months 

 in geological exploration in New York State. 

 Every hour was occupied. He had commenced 

 solid study in earnest, as he had told the members 

 of the " Rostrum " he should do. 



Having entered upon his profession, he taught 

 mathematics seven hours daily. But he found 

 time to make experiments in natural philosophy. 

 The first paper which he brought before the Albany 

 Institute was, "On the Chemical and Mechanical 

 Effects of Steam: with Experiments designed to 

 illustrate the Great Reduction of Temperature in 

 Steam of High Elasticity Avhen suddenly expanded." 



His next published scientific paper was, " On the 

 Production of Cold by the Rarefaction of Air : ac- 

 companied by Experiments." " One of these ex- 

 periments most strikingly illustrated the great 

 reduction of temperature which takes place on the 

 sudden rarefaction of condensed air. Half a pint 

 of water was poured into a strong copper vessel of 

 a globular form, and having a capacity of five gal- 

 lons ; a tube of one-fourth of an inch caliber, with 

 a number of holes near the lower end, and a stop- 

 cock attached to the other extremity, was firmly 

 screwed into the neck of the vessel ; the lower end 

 of the tube dipped into the water, but a number of 

 holes were above the surface of the liquid, so that 

 a jet of air mingled with water might be thrown 

 from the fountain. 



" The apparatus was then charged with con- 



