SOUND. 317 



I 



r Isaac Newton, 

 e Hon. Mr Roberts, 

 e Hon. Mr Boyle, 



Dr Walker, 



Mersennus, 



968 Princip Phil Nat L 2, Prop. 50, 

 1300 Phil. Trans. No 209. 

 1200 E*say of languid Motion, p 29 

 1338 Phil. Trans. No 247. 

 1474 Balistic Prop. 39. 



,Mr FlamsteadandDrHalley, 1142 Exper. per Acad. del. Cimen 



'The Florentine Academy. ill46 P. 141. 



The French Observers, J1172 Du Hamel Hist. Acad. Rex. 



3. Experiments for calculating the velocity of Sound. 



Perhaps the most careful of the experiments which 

 have been performed, were those of Derham, not far from 

 London. One observer ascended a hill to discharge a 

 gun, and others took their stations upon other hills at 

 various distances from three to twelve miles. In order 

 to measure the time, they had a very accurate instrument, 

 with a pendulum vibrating half seconds. That the reader 

 may judge of the particularity and accuracy with which 

 the experiments were performed, we^ubjoin the queries 

 which the philosophers proposed to themselves, and with 

 reference to which the arrangements of the experiments 

 were made. 



' J . How much space sound passed through in a second, 

 or any other interval of time? 2. Whether a gun dis- 

 charged towards the observer, transmit the report in the 

 same space of time, as when discharged the contrary way 1 

 3. Whether, in any state of the atmosphere, when the 

 mercury either ascends or descends in the barometer, 

 sound pass over the same space in the same interval of 

 time ? 4. Whether sound move with greater velocity in 

 the day-time, than in the night? 5. Whether a favorable 

 wind accelerate sound, and a contrary wind retard it ; 

 and how winds affect sound ? 6. Whether sound move 

 with a greater velocity in a calm day, than when the wind 

 blows ? 7. Whether a violent wind blowing transversely 

 accelerate or retard the motion of sound ? 8. Whether 

 sound have the same degree of motion in summer and. 

 winter, by day and night, in snowy and in fair weather ? 

 9. Whether a great and small sound have the same degree 

 of motion ? 10. Whether in all elevations of a gun ; viz. 

 from point blank to ten, twenty, and ninety degrees, 



