SECT, xxxviii.] CONCLUSION. 455 



of the planets ; but they show that creation is the work of 

 Him with whom " a thousand years are as one day, and one 

 day as a thousand years." 



In the work now brought to a conclusion, it has been 

 necessary to select from the whole circle of the sciences a 

 few of the most obvious of those proximate links which 

 connect them together, and to pass over innumerable cases 

 both of evident and occult alliance. Any one branch traced 

 through its ramifications would alone have occupied a 

 volume ; it is hoped, nevertheless, that the view here given 

 will suffice to show the extent to which a consideration of 

 the reciprocal influence of even a few of these subjects may 

 ultimately lead. It thus appears that the theory of dynamics, 

 founded upon terrestrial phenomena, is indispensable for ac- 

 quiring a knowledge of the revolutions of the celestial 

 bodies and their reciprocal influences. The motions of the 

 satellites are affected by the forms of their primaries, and 

 the figures of the planets themselves depend upon their 

 rotations. The symmetry of their internal structure proves 

 the stability of these rotatory motions, and the immutability 

 of the length of the day, which furnishes an invariable 

 standard of time; and the actual size of the terrestrial 

 spheroid affords the means of ascertaining the dimensions 

 of the solar system, and provides an invariable foundation 

 for a system of weights and measures. The mutual attrac- 

 tion of the celestial bodies disturbs the fluids at their sur- 

 faces, whence the theory of the tides and of the oscillations 

 of the atmosphere. The density and elasticity of the air, 

 varying with every alternation of temperature, lead to the 

 consideration of barometrical changes, the measurement of 

 heights, and capillary attraction ; and the doctrine of sound, 

 including the theory of music, is to be referred to the small 

 undulations of the aerial medium. A knowledge of the 

 action of matter upon light is requisite for tracing the 

 curved path of its rays through the atmosphere, by which 

 the true places of distant objects are determined, whether 

 in the heavens or on the earth. By this we learn the nature 



