Vital Physics. 41 



velocity of the accelerating force is alone left, whether its- 

 degree of plus in attraction in one body, as compared 

 to another, be as i to 1,000,000, or as i to 2. The 

 amount of acceleration would be identical. But drop balls 

 made exactly alike, but of different materials, from one 

 height through a resisting medium, and first test them 

 for porosity by the best constructed microscope, and the 

 amount of acceleration between each would better test 

 equal or unequal conditions of attractive force than each 

 being placed in a non-resisting medium. 



Occasionally the man of science indulges in the pleasing 

 recognition of the consistency of scientific men in their 

 modes of interpreting Nature, and recoils with well-measured 

 irony against the man of literature, politics, or theology, 

 contrasting most favourably his own adopted pursuits with 

 those of the, said to be, less positive and more doubtful 

 kinds of study. If the man of science were measured by 

 the standard of consistency in relation to physical force, 

 and votaries from the domain of two of the most exact 

 sciences were canvassed upon this subject, the result would 

 astonish some of the outsiders who came rather to learn 

 than to criticise. Let one on either side be quoted. 



" Our notions," says Professor Graham, " of the range of 

 temperature acquire all their precision from the use of the 

 thermometer. Cold, for instance, is allowed a substantial 

 existence as well as heat, in popular language. What is 

 cold ? It is the absence of heat, as darkness is the absence 

 of light."* 



Contrast this with Mr. Grant's remark upon the tangen- 

 tal force. " The resistance offered by a body to move in 

 a curvilinear orbit has been termed its centrifugal force ; 

 it is therefore equal, and opposite to, the resolved part of the 



* Graham's " Elements of Chemistry," first edition, page 21. 



