106 Trans. Acad. Sci. of St. Louis. 



was then considered as logical and sufficient among the school- 

 men. The writer says: — 



If you ask a ploughman why it is that the loadstone at- 

 tracts iron, he will tell you that he does not know. If you 

 ask of the schoolman he will tell you that it is by reason of 

 an occult property which the loadstone possesses. Now this, 

 as the writer goes on to say, is to say the same that the plough- 

 man said, but in language which might delude the ignorant 

 into the belief that the thing has been explained. 



During the last century and particularly during the latter 

 half, the opposition to the intellectual freedom which the 

 man of science demands, has practically ceased. The so- 

 called scientific method has found its way into the intellectual 

 workshops of all who make pretense to scholarly attainment. 

 In its promise of future good this is the great achievement of 

 the past century. 



When we come to sum up the results of scientific study in 

 physics, it is impossible to do more than to briefly allude to 

 the broader outlines. There is one result which is of central 

 importance. It is the doctrine of the " conservation of 

 energy." The student of our day who reads the earlier 

 papers of Mayer, Helmholtz, Grove, and others, written be- 

 tween 1840 and 1850, will find much to bewilder him. The 

 notation and phrase-coiniDg necessary to state the problem 

 which they were solving, had not yet been effected. New 

 ideas were being brought into focus and there was a new 

 quantity to be dealt with, and measured, but it had no name. 

 They called it " force " but Mayer clearly pointed out in his 

 paper on the mechanical equivalent of heat in 1851 that this 

 was a different meaning from Newton's. 



Speaking of the word Kraft, he says: — 



"I. On the one hand it denotes every push or pull, every 

 effort of an inert body to change its state of rest or motion." 



In his day they sometimes called this "mere force" or 

 " dead force." 



" II. On the other hand the product of the pressure into 

 the space through which it acts, and again the product — or 

 half product — of the mass into the square of the velocity 

 is named force." 



