Gravilation are occasioned by known Terrestrial Motion. 103 
VI. It is urged, that, as attraction is admitted to produce 
certain phenomena in electricity, galvanism, chemistry, mag- 
netism, and optics, so the attraction of gravitation is but an 
analogous power, and might, in like manner, le admitted. 
This argument, to say the least of it, is a very indirect one, 
ayd includes a large appeal to faith. I say again,“and with little 
danger of refutation, that the terms attraction and gravitation 
were chimeras of the middle ages, growing out of the schools of 
astrology and magic; and, in the writings of the illustrious 
Newton, are akin to. the ghosts of the equally illustrious Shake- 
speare, or to the sympathies which filled the heads of all philo- 
sophers in those days, They may be used like characters in an 
algebraic equation; but it is incorrect to substitute them for real 
quantities, or efficient causes, or to set them up in opposition to 
the operative powers of nature, when these are found to be suffi- 
cient to explain phenomena. Nothing, in truth, has tended 
more to retard the progress of science than thus stopping at the 
phenomena of attraction, and then impiously treating this se- 
condary cause as the proximate effect of omnipotent agency, 
though it is found to act mechanically and subordinately, accord- 
ing to certain laws of the distance! 
This is not the place to enter into details to prove that the dif- 
ferent species of mechanical affection, without contact, must all 
be created by different actions of the affected bodies on the me- 
dia which lie between them ; or, mutually, on the surfaces of the 
bodies and the surfaces of the media. I confidently, however, 
calculate on the discovery of the modus operandi by which every 
species of attractive phenomena is effected, as among the pro- 
bable triumphs of experimental philosophy. I, therefore, con- 
sider the argument in support of a terrestrial attraction, drawn 
from the analogy of supposed local attractions, as irrelevant, be- 
cause, in the sense in which the terms are used, I believe that 
no attraction exists, and that in due time this term will give way 
in all the perfect seiences to its explanations or definitions. 
VII. It ts objected that this illustration of the cause of ter- 
restrial gravitation tends to overturn the Newtonian philosophy, 
which is built on the immutable bases of geometry. 
To this | reply, that as the great Newton did not affect to ex- 
plain this cause, but merely admitted this name of the effect, so 
any hypothesis which seeks to account for it can have no neces- 
Mr. Cavendish’s leaden-balls’ experiment, the earth’s attraction is assumed 
to be represented by its diameter—that is, in both cases, a quantity un- 
known, and growing out of the hypothesis of gravity, is taken for granted 
to prove that very gravity. If the known bulk, force, and density, of the 
mountain and the balls were, by exact analogy, to be compared with the 
known bulk of the earth, to determine its force and density, then the results 
will be totally different, and the irrelevancy of the experiments be manifest. 
G4 sary 
