Chap.2. PHILOSOPHY. 87

at the higheft point, to which the motion, that the body hasreceived, will carry it; it will immediately begin to defcend,and at A will receive again as great a degree of motion, as ithad at firft. This motion therefore will carry the body upthe arch AD, as high as it afcended before in the arch AC.Confequently in its return through the arch DA it will acquireagain at A its original velocity, and advance a fecond time upthe arch A C as high as at firft; by this means continuing with-°ut end its reciprocal motion. It is true indeed, that in fad;every pendulum, which we can put in motion, will gradual-ly leffen its fwing, and at length flop, unlefs there be fomepower conftantly applied to it, whereby its motion /hall berenewed; but this arifes from the refiftance, which the bodymeets with both from the air, and the firing by which it ishung: for as the air will give fome obftrudion to the progre/s°f the body moving through it; fo alfo the firing, whereonthe body hangs, will be a farther impediment; for this ftringmuft either hide on the pin, whereon it hangs, or it muft bendto the motion of the weight; in the firft there muft be fome^ e gree of fridion, and in the latter the ftring will make fomere fiftance to its infledion. However, if all refiftance couldh e removed, the motion of a pendulum would be perpetual.

^8. But to proceed, the firft property, I fhall take no-tice of in this motion, is, that the greater arch the penduloushody moves through, the greater time it takes up . thoughthe length of time does not increafe in fo great a proportionas the arch. Thus if C D be a greater arch, and EE a lefler,w here C A is equal to AD, and E A equal to AF; the body,,

when.’