Page 38 - January 2009

Tuscany, [Welling renders the Latin, Hetruria, as Esterinæ; Hutton, et al., translate as Tuscany] situated on a rather high hill, and opposite to the west side of the aforesaid fortress, from which also it is distant about 12 miles. I selected a par- ticular day when the west wind was blowing rather briskly, so that the velocity of sound might be resisted by a contrary wind. But this helped the matter only a little, for towards evening the air was entirely still, or at least was agitated with such a slight breeze as would not have put out the flame of a candle. Having left at this spot certain observers skilled in these inquires to whom I had previously given in charge what they should most particularly attend to, I proceeded to the aforesaid palace of Artermino, where the very Honorable Envoy had preferred to be stationed. According to my orders the culverin was frequently fired between the first and third hour of the night, and I plainly counted 49 seconds between its flash and its report. We also fired some cannons at Artermino, and the aforesaid observers, whom I had left in the fortress, counted between the flash and the report of these only 48 seconds. Hence it appeared that the sound was borne from Artermino to Florence only a second more rap- idly than it was borne contrariwise.
“I do not so fully confide in this observation of mine that I would venture to refer this very small difference of velocity to the force of a favorable or of an opposing wind. In fact a mistake of the observer himself, as he counted the vibrations of the pendulum, might perchance have given occasion to it. This at least might readily occur. For it must needs often hap- pen that he should not see the flash until after the vibration of the pendulum has begun, and that he should hear the
report of the sound before the vibration has been completed; so that in this way he may make his calculation too large by one vibration, whilst in point of fact the interval of time is precisely the same both ways.
“I was hoping however that on the next morning a con- trary wind would perchance arise, (for often at this point, at least with the first dawn of day break, a wind is accustomed to blow from the east) which would better serve for the experiments I had begun. I had ordered therefore the cul- verin to be fired again as soon as day should have dawned, but the wind was propitious neither to my wishes nor my undertaking. In fact it had shifted only a very little towards the north quarter, in so much that the variation of the time and of the velocity of the sound could scarcely be perceived with such a slight change of the wind. I counted, therefore, the usual 49 vibrations of the pendulum, as before. In the mean time I hope thoroughly to try these same experiments as soon as a more suitable weather shall occur, and as more frequent changes of the winds shall afford more convenient opportunities for trying them to better advantage, until at length I shall satisfy myself perfectly.
“As regards the space which sounds traverse in any given time my informants are not yet agreed among themselves, but from certain experiments they conjectured that the mat- ter is as the experiments of the Accademia del Cimento sig- nified.” [This is the end of Averrani’s contribution.]
So much from this acute and skillful man, whose praises I need not repeat. From his observations together with those which the very honorable and distinguished Envoy [Dr. Henry Newton, that is] has communicated to me it is abun-
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