1834.] Miscellaneous. 651 



" The mean annual height of the barometer appears to vary considerably, and 

 to have diminished annually for the last three years: this may have depended on 

 the situation of the instrument*. 

 "The mean often months: in 1831, was 22.932, 

 six ditto, in 1832, „ 23.067, 

 eight ditto, in 1833, ,, 23.054, giving as an annual mean for 

 24 months in three years, 23.018. This is probably near the truth, 



and Dr. Dalmahoy, in his calculations to determine the height of Ootacamund 

 above the level of the sea, assumes it to be 23.005." 



Temperature. — " According to theoretical calculation, the mean temperature of 

 Ootacamund should be 52°. 28. 



" There is some discrepancy of opinion as to the correct method of ascertaining 

 the mean observed temperature. The author of the able article, Meteorology, 

 in the Edinburgh Encyclopedia, after an elaborate consideration of the various 

 proposed methods, gives the preference to the mean of the daily extremes. Ac- 

 cording to this calculation, the mean of the daily extremes for 25 months is 

 5 °.6'8, which we therefore assume as the mean annual temperature of Ootaca- 

 mund. The daily range for nine months of this year, which may be considered as 

 an average season : 



"January, 20-40 June, 15-59 



February, 20*33 July, 10'29 Minimum. 



March, 23*33 Maximum. August, 15*22 



April, 19-73 September, 11-73 



May, 16-48 



Giving a general mean of 17*01 



" The greatest observed annual range (but in different years) appears to be 38* 

 (viz. between 39° and 77°.) 



" It is important to remark, that this range is still betwixt two points, which 

 occur frequently in temperate climates, and is certainly less than wLat prevails 

 in most of them. The maximum observed is 77°, only 2° above what is assumed 

 as summer beat in England ; and the minimum, 38°, is much above what frequent- 

 ly occurs even in the mildest parts of Europe. 



" In stating the observed minimum at 38°, it must be recollected, that the ob- 

 servations were taken at a point raised above the lake, and about half way up the 

 hill bordering the cantonment on the souifr. 



" In the valley below, from the combined effects of radiation, evaporation, and 

 the descent of the colder columns of air by their superior weight, which are 

 moreover comparatively undisturbed by the wind, the temperature frequently 

 falls below freeziug point, and ice is often found in the dry seasons half an inch 

 thick. Hoar-frost is commonly seen extending half way up the hills on every 

 side, disappearing as the power of the sun's rays gradually increase. The differ- 

 ence is most evident in descending into the lower valleys on a dark clear and still 



* The height of Ootacamund, found trigonometricitlly by Captain Ward, was 7361 

 feet. From the Barometrical mean, 23,054, compared with Madras, 29,810, and cor- 



. . 81. 7+57-6 

 rected for temperature of the mean stratum of air —69.6, the altitude 



m 



results, 7221 feet. The boiling point, noted in May, 19S" Farh., gives 7574 feet, but 

 the Thermometer was probably in error. — J. P. 

 6 o 2 



