328 BULLETIN OF THE 



predictions and verifications, as furnishing almost a complete 

 establishment of the atomic and molecular theory of matter. 

 Referring to the ingenious hypothesis of Boscovich, he thought 

 that though well adapted to embrace the two static laws above 

 mentioned, it did not appear equally well adapted to satisfy in 

 any intelligible sense the three kinetic laws. He contended that 

 every attempt at conforming our conception of the ultimate con- 

 stitution of matter to the inductions of experience, would seem to 

 conduct us directly to the atomic hypothesis of Newton. A careful 

 study of the dynamics of the so-called "imponderables" certainly 

 tended to their unification. Admitting the difficulty of framing 

 an entirely satisfactory theory of the resultant transverse action 

 of electricity, he suggested that a tangential force was not accord- 

 ant with any inductions from direct experience ; and was incap- 

 able of direct mechanical realization. Extending the atomic 

 conception of matter to the aetherial medium of space, he con- 

 cluded by urging "the importance in the adoption of mechanical 

 hypotheses, of conditioning them in strict accordance with the 

 operations of matter under the known laws of force and motion, 

 as exhibited in time and space."* 



Among the various public Addresses delivered by Henry on 

 special occasions, reference may be here made to his excellent 

 exposition of the nature of power, and the functions of machinery 

 as its vehicle, concluding with a sketch of the progress of art, 

 pronounced at the close of the Exhibition of the Metropolitan 

 Mechanics' Institute, in Washington, on the evening of March 

 19th, 1853. After representing to his hearers the close physical 

 analogy between the human body as a moving machine, and the 

 steam locomotive under an intelligent engineer, he remarked: 

 " In both, the direction of power is under the influence of an 

 immaterial, thinking, willing principle, called the soul. But this 

 must not be confounded as it frequently is with the motive power. 

 The soul of a man no more moves his body, than the soul of the 

 engineer moves the locomotive and its attendant train of cars. 

 In both cases the soul is the directing, controlling principle; not 

 the impelling power, "f 



Views of Education. — Another address deserving of special 

 notice (delivered the following year,) is his introductory dis- 

 course ibefore the "Association for the Advancement of Educa- 

 tion," as its retiring President. In this, he maintained that 

 inasmuch as "the several faculties of the human mind are not 

 simultaneously developed, in educating an individual we ought 

 to follow the order of nature, and to adapt the instruction to 

 the age and mental stature of the pupil. Memory, imitation, 



* Proceed. Am. Assnc. Albany, Aug. ]851, pp. 84-91. 

 t Closing Address Metr. Mech. Inst. Washington, 1853, p. 19 



102 



