182 Meteorological Observations at the Madras Observatory. 



The mean atmospheric pivssure through mi, the whole year wis 29*830 

 inches ; — 0 014 less than the average of twenty years. The highest reduced 

 readings were "30 018 on February I2t\i, and 30* 123 on December 31st : — 

 the lowest was 29'508 on June '29th. 



The greatest degree of heat registered in the shade, was 107°' I, on May 

 30th : in full sunshine, three feet from the groan i, 124 3 5 on May 17th. 

 The lowest temperatures were recorded on February 2/rh and December 

 31st, on which days the shade minimum went down to 63 0 5and 62 D, 6, 

 and the grass thermometer to 58° 3 and 56 3 '9 respectively. The mean 

 annual temperature was 81 3,or 0*7 above average. That of evaporation, 

 as shewn by the wet bulb thermometer, was 74 9, or 0 9 above average. 

 The mean claily range for the year w T as 14°5. 



The dryest day in the year was June 1 2th, when the percentage of 

 humidity fell so low as 42, and the mean dew point was 63°T, or 27 0, 4 

 less than the nvan temperature of the day. Complete saturation of the 

 atmosphere occurred but "once, viz., on October 31st. 



Rain fell on 98 days The quantity measured was above one inch on 

 113 days, but the greatest fall was only 3 28 inches, on December 14th. 

 The total fall during the year was only 38T8 iuches, leaving a deficiency 

 of 1257 inches or exactly one-fourth of the whole yearly average. 



The mean daily velocity of the wind was 151 mites, from S E by S. 

 It was recorded half daily, and ranged between 165 miles on May 22nd p. m., 

 and 14 miles on October 20th a. m. It is worthy of remark, that, al- 

 though the wind at Madras is insignificant in comparison of that, in Eng- 

 land, it is far more constant, and rarely ever quite still. Not one single half 

 clay has baen perfectly calm since the velocity gauge was first put up, on 

 September 1st 1861. During the steadier mouths of the year, the result- 

 ant velocity, or that in which the force from each point of the compass is 

 ^aken into account, often nearly equals the mean velocity, and rarely falls 

 short of three-fourths of the latter quantity. In the two variable periods 

 however, the difference is very considerable. Thus, in the latter half of 

 March, while the actual daily wind was 125 miles, from N N E, 

 the resultant value was only 40 miUs, from East ; but in the latter half of 

 October, when the daily motion was 116 miles from S E, the resultant 

 value was only 3 miles per day, from S S W. This remarkable effect of 

 contrary winds must surely have considerable influence upon the public 

 health and mortality returns ; since any miasmatic vapors existing in the 

 atmosphere at the time, though stirred up and diffused by the actual daily 

 wind, will still be blown backwards and forwards, so as to continue hanging 

 about, or at least only very slowly receding from, the same spot ; while at 

 other times they would be wafted a thousand mile3 off iu les3 than a 

 single week. The number of half days the wind blew from each point of 

 the compass is given in the following table :— 



North 



N by B 

 N NE ... 

 NEby N...... 42 



North East.... 16 



NEbvE 32 



ENE 21|S SE. 



EbyN 13SbyE 



31|East 14 



28 E by S , 13 



30 E SE , 17 



S E by E 14 



South East.... 21 



SEbyE 33 



South 



Sby W 



SSW 



SWby S.... 

 South West. 

 3 W bv W.. 



W S W 



Why S 



West 5 



W by N I 



W N W 4 



NTWbyW.... 1 



North West.... 2 



NWbyN * 



NNW 9 



M by W 15 



from N E Quarter 213.1 From S E Quarter 216. from S W Quarter 260. From N W Quarter 41. 



NORMAN ROBERT POGSON, 



Government Astronomer, 



