Excerpt from Results of the Meteorological Observations Made at the Government Observatory, Madras, During the Years 1861-1890: Under the Direction of the Late Norman Robert Pogson, C. I. E. F. R. A. S

It has been used since 1874 with the correction ]o'5. It is rather remarkable that the freezing point has fallen.

The corrections for the other thermometers were determined in the following way. For the dry maxi mum the correction was taken as the difference of readings at 10 a.m. Between the dry bulb (corrected) and the dry maximum. For the dry minimum the correction was taken as the difference of reading at 10 p.m., (or latterly 8 p.m.) between the dry bulb (corrected) and the dry minimum. The corrections for the wet minimum and grass minimum were similarly got by comparison with the wet bulb at 10 p.m., and the corrections for the sun maximum also by comparison with the dry bulb at the same hour. The evening and not the morning reading being taken in this case on account of the very unsatisfactory nature of comparisons that are made of sun thermometers in vacuo in day-light, and because the thermometer should be exposed long before 10 a.m. In each case the actual correction applied for each half month was the mean of the corrections obtained for that half month.

Anemograph. - Since 1864. The wind direct-ion and velocity have been obtained from the records of a Beckley anemograph, by Adie, carried on a wooden framework erected on the roof of the Astronomer's house. The cups of the anemograph are about 87} inches in diameter and the distance from centre to centre of two opposite cups is 4 feet. The height of the cups above ground is 44 feet and the height above the parapet of the building is 18 feet. I can find no record of any tests that were made as to the accuracy of the scale of this instrument before it was sent to Madras, but as it was made under the direction of the late Professor Balfour Stewart it is probable that due care was taken regarding this important point. The readings for wind velocity have been accepted without any correction, and the instrument has been taken as the standard for smaller instruments used in other parts of the Presidency. The accuracy as regards wind direction has been tested from time to time. The record of direction is not thoroughly trustworthy when the velocity falls below two miles an hour.

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