214; Mr. Galbraith on the Velocity of Sound. 



served that he exhibited at the glass an order for heaving up ; 

 and the bell was raised. When he was liberated, and while 

 he was receiving the congratulations of his friends, I heard 

 him say to one of them that "his feeling was one of extreme 

 delight at the moment when, looking out from the little win- 

 dow of the air-chamber, after the full success of his experiments, 

 he saw his diving-bell emerging slowly from the watey, and 

 the persons who had descended come out from it in safety." 



There is an exceedingly interesting but apparently para- 

 doxical consequence resulting from the theory upon which the 

 air-chamber has been constructed: 1st, Let the diameter of 

 the pipe between this chamber and the bell be supposed to be 

 increased until it be sufficient to admit a man, and let a rope 

 ladder be inclosed in it. — 2nd, Let the air-chamber be sub- 

 divided into two, with a man-hole in the partition, and another 

 in the side. It is evident that by a process analogous to that of 

 passing locks in a canal, and identically the same with that used 

 by Mr. Steele himself in the transmission of the roll of paper 

 through the two air-tight cocks, that a man might go down 

 unwet from deck, to blast rocks, or do any other work at the 

 bottom of the sea ! The same thing might be effected by the 

 addition of a third compartment to the bell below, between 

 the communicating chamber and the open bell ; in which case, 

 the air-chamber above water would (for this particular pur- 

 pose) cease to be necessary. 



It is manifest, however, that these two modes of passing and 

 repassing between the deck and the bottom, might be used 

 even in combination. I have the honour to be, &c. 



Portsmouth, Sept. 1826. * * *. 



XXXII. On the Velocity of Sound. By Wm. Galbraith, 



Esq. M.A.* 

 r I^HE determination of the motion of sound in an elastic 



■*■ medium has frequently been an object of discussion. No- 

 thing very important relative to the mathematical theory was 

 effected till the time of Newton. That great philosopher de- 

 voted the eighth section of the second book of his Philosophies 

 Naturalis Principia Mathematica to the determination of mo- 

 tion propagated through fluids, which has served, in a great 

 degree, for the basis of most that has been written on the sub- 



i ect - 



In the scholium subjoined to the last proposition in that 

 section, he enters upon the motion of sound transmitted 



* Communicated by the Author. 



through 



