1823.] Mr. Goldhigham on the Velocity of Sound, 203 



having repaired to the station at the top of the Observatory 

 building, a Httle before the expected time, and each holding his 

 chronometer so that he could distinctly hear the beats, began to 

 count the instant he saw the flash, and continued counting until 

 he heard the report ; the number of beats between the flash and 

 report was then immediately put down upon a slip of paper, by 

 each observer, without communication with the others, and the 

 papers delivered to me for their contents to be registered ; the 

 height of the thermometer, barometer, and hygrometer, with the 

 direction of the wind and state of the weather, were also observed 

 at the time, and registered ; and in this manner the whole of the 

 experiments were made. The situations of the guns with respect 

 to the station from which the observations were taken, was very 

 favourable, being in the direction, one of NE, and the other of 

 the SW monsoons — with the southerly wind and sea breeze 

 (both which prevail at certain seasons of the year), blowing 

 between the two. The guns used were 24 pounders, charged 

 with 8 lbs. of powder, and both pointed, not exactly towards the 

 station, but in a direction not far from it. 



The distances were ascertained with great care; first, by a 

 survey made for the purpose, a base having been measured, and 

 the angles taken with a grand circular instrument, similar to that 

 used on the trigonometrical surveys.* Secondly, by using two 

 or three of Col. Lambton's distances and bearings found by the 

 trigonometrical survey. 



The results were thus deduced, and verified indifferent ways; 

 and I have reason to think that the distances of the guns from 

 the Observatory station are very accurately given. The mean 

 of twelve results made the distance of the Mount gun from the 

 station 29647 feet ; and the mean of six results gave the distance 

 of the Fort gun from the station 13932*3 feet. 



We see, as I before remarked, that the distance of one gun 

 from the station is nearly double that of the other, and this will 

 be found an advantage, in showing whether sound travels equally 

 during its progress. 



The experiments are given in eleven tables.f 



Table I. Contains the experiments of each day with the 

 Mount gun, together with the state of the atmosphere and the 

 direction of the wind at the time of observation : the titles at 

 the heads of the columns render a particular explanation unne- 

 cessary — the number of observers is stated in the third column, 

 and the mean of their observations in the ninth. 

 . Table II. Contains the mean of observations of each day, 

 when the air was calm. 



• I have not given the details of the survey, as that would swell the paper to an 

 incohvenient size : the base, however, was measured with great care twice, and generally 

 six observations were taken for finding each angle, each observation differing very little 

 from the other. 



•]- These Tables are necossarily omitted in this abstract. 



