On the Velocity of Sound. 155 



and 28tli of June, the long metal twelve-pounders have been 

 used on both stations, loaded with six pounds of gunpowder. 

 The cartridges had been carefully prepared by Sergeant- Major, 

 now Captain or Lieutenant Essen ? ; the gunpowder, if not 

 from the sanie barrel, was from the same magazine. The 

 propriety of trying its strength did not then occur to us. The 

 guns were constantly discharged, loaded, primed, and managed, 

 by the same persons, either non-commissioned officers or cadets. 

 The cartridge-bags were of fustian, and not of paper. Instead of 

 wadding, a sod was rammed down on the charge as strongly as 

 possible. I cannot therefore see any of the differences pointed 

 out by Mr Meikle. I had the observations of Captain Parry 

 and Lieutenant Foster in high latitudes, and low temperature, 

 reduced to the same pressure and temperature with our own 

 experiments. • The results agree strikingly : an account of this 

 will be shortly published in the Transactions. 



Mr Meikle, in reply to thts communication, has sent us the 

 following remarks. 



With regard to the proposed apparatus, it has not yet been con- 

 stnicted ; but I have had some correspondence with Professor Moll on 

 the subject, and it is probable that an arrangement will be made for 

 following up the scheme; especially as I have suggested some ma- 

 terial simplifications on the original proposal — particularly that, instead 

 of placing such an apparatus or clock, at each end of the range, 

 it would be preferable to have only one in the middle, or somewhere 

 in the line between the observers. By this means, the ear would not 

 be so overpowered by the prodigiously louder sound of the bell beside 

 it, than of that it was meant to heai*. By placing observers, too, on 

 opposite sides of the machine, both in the line of the direction of the 

 wind, and also in another at right angles to it, the effect of the wind 

 could be ascertained ; and that, perhaps, even when the sound could 

 not be heard to windward ; — a method which, for several reasons, could 

 scarcely be made available in the case of cannon. 



As to the conjectures, which I formerly threw out, to account for 

 some slight anomalies in Professor Moll's experiments, it never oc- 

 curred to me that the two guns, so judiciously employed by that dis- 

 tinguished philosopher and his able associates, were such as would ei- 

 ther be accounted of different sizes, or reckoned to be differently 

 charged, &c. What I alluded to, was merely small or accidental dis- 



