DISCOURSE OF W. B. TAYLOR. 273 



assistance to the performer. In remarking the impression of being 

 moved, while steadily watching a series of passing canal boats, he 

 referred the impression (amounting almost to a sensation of move- 

 ment on each boat reaching a certain point,) to the relative angle 

 of vision formed by the moving body. 



He made a number of experiments on the flow of water jets under 

 varying conditions : also observations on sonorous flames when pass- 

 ing into a stove-pipe of eight inches diameter and about ten feet in 

 length : on the comparative rates of evaporation from fresh and 

 from salt water : on the slow evaporation of water from the open 

 end of a U-shaped tube, and the much greater rapidity of evapora- 

 tion when the tube is open at both ends : extended notes of which, 

 with a great number of other researches, perished in the flames. 



In 1844, he published a Syllabus of his Lectures at Princeton. 

 In December of that year he presented to the Philosophical Society 

 a communication of a somewhat more theoretical character than 

 usual, on the derivation and classification of mechanical motors. 

 He refers these to two classes ; the first, those derived from celes- 

 tial disturbance (as water, tide, and wind powers), and the second, 

 those derived from organic bodies or forces (as steam and other heat 

 powers, and animal powers). The forces of gravity, cohesion, and 

 chemical affinity are not included, since these tend speedily to stable 

 equilibrium; and they become sources of mechanical power only 

 as they are disturbed by some of those before mentioned. It is not 

 the running down of the water-fall, or the clock- weight, which is 

 the true origin of their useful work, but the lifting of them up. 

 The same is true of the power derived from combustion. He then 

 adds that his second class (the forces derived from the organic world) 

 might perhaps by a similar process of reasoning Ibe derived from 

 the first class; (that of celestial disturbance;) regarding "animal 

 power as referable to the same sources as that from the combustion 

 of fuel," and the action of the vegetative power as "a force derived 

 from the divellent power of the sunbeam," being simply a case of 

 solar de-oxidation. Organism vegetable and animal, he considers 

 as built up under the direction of a vital principle, which is not 

 itself a mechanical force. Volcanic power is neglected as compara- 

 18 



