HERMANN VON HELMHOLTZ 



the Connection of the Physical Sciences was published 

 in 1834, but little is said about the 'connections,' 

 except that a knowledge of one science is often 

 essential to the successful prosecution of another. 

 In January 1842, Grove delivered a lecture in the 

 London Institution on the Correlation of the Physical 

 Forces, which was afterwards expanded into a well- 

 known volume. This work shows that of the 

 various forms of energy existing in nature, any one 

 may be transformed into any other, the one form 

 appearing as the other disappears. No doubt this 

 book, written in a clear and lambent style, familiarised 

 the public mind with the new conception, and it 

 also influenced scientific opinion. Clerk Maxwell 

 says of this epoch in the history of science : * The 

 fathers of dynamical science found a number of 

 words in common use expressive of action and the 

 results of action, such as force, power, action, impulse, 

 impetus, stress, strain, work, energy. They also had 

 in their minds a number of ideas to be expressed, and 

 they appropriated these words as they best could to 

 express the ideas. The words force, vis, kraft, came 

 most readily to hand.' 



In and about 1842 the speculations and researches 

 of Robert Mayer of Heilbronn appeared. Only to a 

 limited degree an experimenter, Mayer had yet 

 wonderful clearness of vision and originality, and 

 although his premises were sometimes inadmissible, 

 and his reasoning faulty, he enunciated a true 

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