PHILOSOPHICAL SOCIETY OF WASHINGTON. 233 



familiarity with the logical processes of the higher mathematics, 

 he resolutely set himself to work to master the intricacies of the 

 differential calculus. 



Having finished his academic course and passed with honor 

 through his examinations, he then through the warm recommen- 

 dation of Dr. T. Ptomeyn Beck — the distinguished Principal of 

 the Academy, obtained a position as private tutor in tlie family 

 of General Stephen Van Rensselaer.* As this duty did not exact 

 more than about three hours a day of his attendance, he applied 

 his ample. leisure (having in view the medical profession) — partly 

 to the assistance of Dr. Beck in his chemical experiments, and 

 partly to the study of Anatomy and Physiology, under Doctors 

 Tully and Marsh. 



His devotion to Natural Philosophy which had only grown and 

 strengthened with his own growth in knowledge, led him con- 

 stantly to repeat any unusual experiment as soon as reported in 

 the foreign scientific journals ; and to devise new modifications 

 of the experiment for testing more fully the range and operation 

 of its fundamental principles. 



CommunicaUons to the Albany Instititte. — The "Albany In- 

 stitute" was organized May 5th 1824, by the union of two older 

 Societies; with General Stephen Van Rensselaer as its Presi- 

 dent:"!" and young Henry became at once an active member: 

 though with his modest estimate of his own attainments, he 

 preferred the part of listener and acquirer, to that of seeming 

 instructor, till urged by those who knew him best to add his 

 contributions to the genera] garner. 



Henry's first communication to the Institute was read October 

 30th 1824 (at the age of about twenty-six years) and was "On 

 the chemical and mechanical effects of steam : with experiments 

 designed to illustrate the great reduction of temperature in steam 

 of high elasticit}^ when suddenly expanded."! From the stop- 

 cock of a strongly made copper vessel in which steam could be 

 safely generated under considerable pressure, he allowed an occa- 

 sional escape ; and he showed by holding the bulb of a thermo- 

 meter in the jet of steam, at a fixed distance (say of four inches) 

 from the orifice, that as the temperature and pressure increased 

 within the boiler, the indications of the thermometer without 

 grew lower; — the expansion and consequent cooling of the escap- 



* Presiding Officer of the original Board of Trustees of the Albany 

 Academy. 



t Tlie Albany Institute resulted from the fusion of " The Society for the 

 Promotion of U.-^efnl Arts in the State of New York," organized Feb. 1791 

 (incorporated April 2nd 1804,) and the "Albany Lyceum of Natural His- 

 tory" formed and incorporated April 23rd 1823: of which latter society, 

 Henry had been a member. 



i Trans. Albany Inst. vol. i. part 2, p. 30. 



7 



