204 Mr, Goldingham on the Velocity of Sound, [Sept. 



Table III. The mean of observations of three days, when the 

 wind was in the SE quarter. 



Table IV. The mean of observations of three days, when the 

 wind was in the NE quarter. 



Table V. The mean of observations of three days, when the 

 wind was SW by W, or N\V. 



Table VI. The experiments with the Fort gun, arranged as 

 those in Table I., with the Mount gun. 



Tables VII, VIII, IX, and X. The experiments with the Fort 

 gun arranged according to the state of the wind, as in the former 

 Tables of experiments with the Mount gun. 



Table XI. Shows the mean motion of sound for each month 

 at the Madras Observatory, as found by the experiments, at the 

 mean height of the thermometer, barometer, and hygrometer, 

 given in the table. 



Upon a cursory inspection of Tables I. and IV. it will be seen 

 that the motion of sound varies under different states of the 

 atmosphere and weather : that, according to the first table, 

 sound at one time has been as long as 27-6 seconds in travel- 

 ling from the Mount to the Observatory station ; and at another 

 time only 24*8 seconds ; the distance being 29547 feet. In the 

 first case, therefore, the velocity of sound was only about 1078 

 feet in a second ; while, in the other, its velocity was nearly 

 1191^ feet. The extremes in Table VI. show a still greater 

 difference. This proves the necessity for making experiments 

 during a long interval, in order to obtain an accurate general 

 result. 



In Tables II. and VII. we find, as the thermometer rose, 

 the atmospherse at the same time decreasing in density and 

 increasing in its elasticity, that the sound moved with greater 

 rapidity. 



That with the wind in the SE quarter the velocity was consi- 

 derably increased, both from the Mount and Fort ; more, how- 

 ever, m proportion, as might be expected, from the former than 

 the latter. 



That with the wind at NE. the sound from the Fort gun tra- 

 velled with a greater, and from the Mount gun with a less velo- 

 city than when the wind was in any other direction ; that wind 

 being favourable for increasing the velocity from the Fort, and 

 unfavourable from the Mount: the full effect of the wind, how- 

 ever, is not to be ascertained by this table alone, as the thermo- 

 meter during the time the NE wind prevails is comparatively 

 low, and the barometer high ; both which, as will have been 

 seen by inspection of the tables, occasion the sound to travel 

 slower than ordinary. 



The wind SVV. W. and NW. the velocity from the Mount was 

 accelerated, and that from the Fort retarded ; but not in the 

 degree that would have taken place had the thermometer, baro- 



