324 THE SECONDARY MECHANICAL SCIENCES. 



plete list of the persons by whom such additions 

 have been made; but to present a view of the 

 progress of each of those branches of knowledge 

 as a speculative science ; to point out the Epochs 

 of the discovery of those general principles which 

 reduce many facts to one fact; and to note all 

 that is most characteristic and instructive in the 

 circumstances and persons which bear upon such 

 Epochs. A history of any science, written with 

 such objects, will not need to be long ; but it will 

 fail in its purpose altogether, if it do not distinctly 

 exhibit some well-marked and prominent features. 

 We begin our account of the Secondary Mecha- 

 nical Sciences with Acoustics, because the progress 

 towards right theoretical views, was, in fact, made 

 much earlier in the science of Sound, than in those 

 of Light and of Heat ; and also, because a clear 

 comprehension of the theory to which we are led in 

 this case, is the best preparation for the difficulties 

 (by no means inconsiderable) of the reasonings of 

 theorists on the other subjects. 



