VOL. XXVI.3 PHILOSOPHICAL TRANSACTIONS. 38/ 



made at Langdon, nor in any others. Whether sound move equally in ascents 

 and descents, that is, from the top to the foot of a hill, and from the bottom 

 to the top of the same, I despaired of ever satisfying myself; for want of hills 

 of a sufficient height, for making a competent number of experiments to this 

 purpose. 



§ 9' Of ihe Motion of Sounds in Italy. — I was informed by Mr. Richrird 

 Townley, that sound is seldom heard at Rome, at such distances as in England, 

 and the northern climates; particularly he affirmed, that when he was at Rome, 

 and the guns of the castle of St. Angelo were fired, the report was much more 

 languid on Monte Trinito, than any other place at the same distance. And 

 Mr. Townley's brother also affirmed, that being once at the castle of Gendolfo 

 (a place on an eminence near lake Albanus, about 12 Italian miles from Rome) 

 the report of the great guns from the castle of St. Angelo seemed to him 

 languid and weak ; and at another time, riding in his chariot round the walls of 

 the said castle, the report did not seem so loud there, as elsewhere. But Dr. 

 Newton, envoy at the court of Florence, informed me, that travelling from 

 Bologna to Florence, he heard at St. Michael's in Bosco, near Bologna, the re- 

 port of the great guns of Mirandula, though 40 miles off; and the following 

 night he heard them in the Apennine mountains, 20 miles farther off. 



S. Averrani, by order of the great duke, caused a culverine to be discharged 

 several times, in the lower castle of Florence, between the first and third hours 

 of the night; and some were appointed at Leghorn to observe the report. 

 Those stationed at Lanterna and Mazzoco, heard nothing of it (perhaps the 

 roaring of the sea drowned the sound) ; but others, that were orr the warks of 

 the old castle, called Donjon, and sent to Monte Rotondo about 5 miles from 

 Leghorn towards Monte Nero, heard it distinctly ; the distance of this castle of 

 Florence from Monte Rotondo, is in a right line computed to be little less than 

 55 miles; and it is observable, that the intermediate country is hilly, which 

 must necessarily retard somewhat the velocity of the sound: add to this, that 

 the same evening there was a gentle westerly wind, which (Leghorn being 

 situated to the south west in respect of Florence) must be supposed to hinder 

 in some measure the free expansion of the sound. 



But, in order to have an open free place, that tract of the sea between 

 Leghorn and Porto Ferraio was pitched on, which, according to the calculation 

 of the most skilful sailors, is about 6o miles ; and any wind, whether with or 

 against it, retards the sound and renders it less sonorous; the reason of which 

 may be, that the roaring of the agitated sea mars it more, than the current of 

 the air the same way assists it; therefore the sound is then only heard when the 



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