ESSENTIAL AND PECULIAR. 



57 



of gravity, and to develope the cause of the curves or ellipses of falling 

 bodies. Both these desiderata he accomplished by a series of reasonings and 

 calculations equally ingenious in their origin and demonstrative in their result 

 and ascertained the truth of his principles by applying them, practically and al- 

 ternately, to the phenomena of the heavens, and to a variety of terrestrial bodies. 

 The bold and beautiful theorem being at length arrived at, and unequivo- 

 cally established — a theorem equally applicable to the minutest corpuscles, 

 and the hugest aggregations of matter — that all the particles of matter attract 

 each other directly as their mass, and inversely as the square of their dis- 

 tance, he at once beheld the cause of those perturbations of motion to which 

 the heavenly bodies are necessarily and so perpetually subject: it became mani- 

 fest, that the planets and comets, reciprocally acting and acted upon, must 

 deviate a little from the laws of that perfect ellipse which they would pre- 

 cisely follow if they had only to obey the action of the sun : it was manifest, 

 that the satellites of the ditferent planets, exposed to the complicated action of 

 the sun, and of each other, must evince a similar disturbance : that the corpus- 

 cles which composed the diiferent heavenly bodies in their formation, perpetu- 

 ally pressing towards one common centre, must necessarily have produced, in 

 every instance, a spherical mass : that their rotatory motion must at the same 

 time have rendered this spherical figure in some degree imperfect, and have 

 flattened these masses at their poles ; and, finally, that the particles of immense 

 beds of water, as the ocean, easily separable as they are from each other, and 

 unequally operated upon by the sun and the moon, must evince such oscilla- 

 tions as the ebbing and flowing of the tides. The origin, progress, and per- 

 fection of these splendid conjectures, verifications, and established principles, 

 were communicated in two distinct books, known to every one under the 

 titles of his "Principia" and his " Optics ;" — books which, though not actu- 

 ally inspired, fall but little short of inspiration, and have more contributed to 

 exalt the intellect of man, and to display the perfections of the Diety, than 

 a".v thing upon which inspiration has not placed its direct and awful stamp. 



LECTURE V. 



ON THE PROPERTIES OF MATTER, ESSENTIAL AND PECULIAR. 



(The subject continued.) 



We closed our last lecture with remarks on the universal operation of the 

 common principle of gravity over matter in all its visible forms, from the 

 minutest shapes developed by the microscope, to the mightiest suns and con- 

 stellations in the heavens. But we observed, also, that, independently of this 

 universal and essential power of attraction, matter possesses a variety of pe- 

 culiar attractions dependent upon circumstances of limited influence, and 

 which consequently render such attractions themselves of local extent. 



These I will now proceed to notice to you in the following order : — 1st, 

 The attraction of homogeneous bodies towards each other, which is denomi- 

 nated, in chemical technology, the attraction of aggregation: 2dly, The 

 attraction of heterogeneous bodies towards each other, under particular cir- 

 cumstances, which in its more obvious cases is denominated capillary attrac- 

 tion : 3dly, The attraction of bodies exhibiting a peculiar degree of affinity 

 to each other, and which is denominated electrive attraction: 4thly, The 

 attraction of the electric fluid ; and, 5thly, That of the magnetic. 



I. The law of physics, which has rendered every material substance capa- 

 ble of attracting and being attracted by every other material substance, seems 

 at the same time to have produced this power in a much stronger degree be- 

 tween SUBSTANCES OF LIKE NATURES. Thus, drops of Water placed upon a 

 plate of dry glass have a tendency to unite, not only when they touch, but 

 when in a state of vicinity to each other ; and globules of quicksilver still 



