Chambers's Edinburgh Journal, No. 457, page 19 by Various Authors
<< Return to Title Details & Download20
hill, and soon gives over the effort. The body swings down-hill with increasing rapidity, because weight and velocity are then both driving it; it swings up-hill with diminishing rapidity, because then weight is pulling it back in opposition to the force of velocity. Weight pulls first this way, then that way; velocity carries first this way, then that way: but the two powers do not act evenly and steadily together; they now combine with, and now oppose each other; now increase their influence together, and now augment and diminish it inversely and alternately; and so the suspended body is tossed backwards and forwards between them, and made to perform its endless dance.
It is related of Galileo, that he once stood watching a swinging lamp, hung from the roof of the cathedral at Pisa, until he convinced himself that it performed its vibratory movement in the same time, whether the vibration was one of wide or of narrow span. This traditionary tale is most probably correct in its main features, for the Newtons and Galileos of all ages do perceive great truths in occurrences that are as commonplace as the fall of an apple, or the disturbance of a hanging lamp. Trifles are full of meaning to them, because their minds are already prepared to arrive at certain conclusions by means of antecedent reflections. Simple and familiar incidents, thus accidentally associated with the history of grand discoveries, are the channels through which the accumulating waters at length descend, rather than the rills which feed the swelling of their floods. The orchard at Woolsthorpe, and the cathedral at Pisa, were outlets of this kind, through which the pent-up tide of gathering knowledge burst. If they had never offered themselves, the laws of universal gravitation and isochronous vibration would still have reached the world.
If the reader will hang up two equal weights upon nearly the same point of suspension, and by means of two strings of exactly the same length, he will have an apparatus at his command that will ena