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Show On tbe Vis Inertia ochzz‘lcr, clearly (at leaf: to me he does not) that there is really flab a property in matier. He fays, No.2. ‘ Leta given body or mafs of 480 matter be called a, and let any given celerity be called c. That ca/er/ty doubled, tripled, See. or halved, thirded, (Sec. will be 2 c, 3 5, See. or it, f6, 85c. refpet‘lively : Alfo the 1201sz doubled, tripled, or halved, thirded, will be 2 (z, a, or 'i‘d, f a, refpeétively.' Thus far is clean-But he adds, ‘ Now to move the body a ‘ with the celerity 6, requires a certain force to ‘ be imprefl‘ed upon it; and to move it with a ce~ ‘ lerity as 2 6, requires twice t/Jatforce to be im‘ prefi'ed upon it, &c.' Here I fufpeét fome mif'rake creeps in by the author's not diftinguifh- ing between a great force applied at once, or a finall one continually applied, to amafs of matter, in order to move iti. I think it is generally allowed by the philofophers, and for aught we know, is certainly true, that there is no mafsofrnatter, how great foever, but may be moved by any force how [mall foever *‘ (taking friction out ofthe quefiion3) and this {mall force continued, will in time bring the mafs to move with any velocity whatfoever. -Our author himfelf {cents to allow this towards the end of the fame No.2. when he is fubdi~ viding his celerities and forces: for as in conti- nuing the divifion to eternity by his method of 1 [It would not have been ineonfiflent in Mr. Baxter, to admit an augmentation of force from fuccefhve applications of it; in WhiCh cafe a {mall force often repeated, is no longer a {mall force, b" becomes a large/1m of forces. E.] " [See the following note. [M P.] J in aLetz‘er to Mr. Baxter. it, it, ;c, it, &c. 4811 . fraction of veloycity that £0542? tIdCVCr COme to a. lerity at all; {0 dividing the forceo'c, 0r noce- manner, you can never come to a fraelilondd; fame that Will not produce an equal fraction of celei-J'ItCC iS-iglflterlée tltifin lS tIllie mightyVisInertize, andwlhié ng‘ ; -w en the greatef'r aflionabl of matter Will give wa to, or be c e mafs leaf} allignable force?y Suppofe twbngogliiesbz thfii to the tun and to one another, exactly e ui oqiuil in jove 5 balance; fuppofe no friction inqthg exec ter of motion, in the beam or elfewhereIfn- mufketothen were to light on one of them would he not give motion to them both, caufin' onet defcend and the other to rife? lfit is objec'ftged tha: the force of gravity helps one globe to defcend I anfwer, the fame force oppofes the other's rifin f Here 18 an equality that leaves the whole motigri to be produced by the mufleeto, without whom thofe globes would not be moved at all.-What then does Vis Inertia: do in this cafe? and what other effeét could we expect y‘tr'iere were 720/;sz t/ng .9 Surely if it were any thing more than a phantom, therle plight be enough ofit in fuch wfl f0o trifling a force? ' , ' ii are , b y i ts oppofition res to anni to motion Our author would have reafoned more clearly I think, if} as he has uled the letter a for a cer: tam quantity ofrnatter, and L‘ for a certain quan- tity of celerity, he had employed one letter more and-putfperhaps, for a certain quantity offorce: This let us fuppofe to be done; and then as it is 13.] rI3- 5', q q a maxim WillllllllllillIlllullllllllllll 1-. lulu- l mu ' |
