338 



PHILOSOPHICAL TRANSACTIONS, 



[anno 1698. 



purging, removing obstructions, tempering the hot intrails, &c. it may have 

 the same effects with common water when drunk plentifully. 



One may drink many glasses of this water, beginning with 4, 6, or 8 every 

 morning, and augmenting to 12, 18, 20, or more, according as the stomacli 

 is able to support it. This water passes readily by urine, and many persons are 

 purged by it. Sometimes one may mix with it some diuretic salt, to make it 

 pass more freely, and remove the more obstructions. At other times one may 

 put some manna, or such-like, for making it more purgative. One may wash 

 also in the mud of the fountain, according to necessity.* 



Some Experiments and Observations concerning Sounds. By Mr. JValkeri 



N° 247, p. 433. 



Intending to try the swiftness of sounds, I provided a pendulum, which had 

 two vibrations in l" of time ; this I carefully adjusted at a watch maker's ; it was a 

 piece of small virginal wire, with a pistol bullet at its end, the length was 9 ^"-g. 

 inches to the middle of the bullet : I first made it about -p\ of an inch longer, 

 viz. J- of the length of a pendulum that vibrates 2ds, but found it too slow, 

 which I expected from the air's resistance. 



I took this pendulum, and standing over against a high wall, I clapped two 

 small pieces of boards together, and observed how long it was ere the echo 

 returned ; thus removing my station till I found the place to which the echo 

 returned in about half a second. But that I might distinguish the time more 

 nicely, I clapped every second of time 10 or 15 times together ; so that by 

 this means I could the better discover whether the distances between the 

 claps and the echoes, and the following claps were equal. And though it be 

 very difficult to be exact, yet I could come within some few yards of the 

 place I sought for, thus: I observed the two places where I could but just 

 discover that I was too near, and where I was too far off; and from the mid- 

 way between them I measured to the wall, which measure doubled was the 

 space that the sound moved in half a second. 



Here follow the numbers of English feet which a sound moved in one 

 second of time at several trials. 



* Further accounts of these mineral waters by Mons. Boulduc in 169.9, and by Mons. Morand in 

 1743, are inserted in the Memoirs of the Royal Parisian Academy of Sciences for the aforesaid years. 

 t It will readily be perceived that, from the wida ditterences among the numbers, these experi- 



