AnnualReport-1927

In the following table the mean monthly temperature and humidity in the Underground Chamber are compared with the temperature and humidity in the Open Air.

Mean Monthly Temperature and Relative Humidity in the Underground Chamber and in the Open Air,
during the year 1997.

Month In Underground Chamber In the Open Air. Excess of Underground Chamber over Open Air. Temperature Relative Humidity Temperature Relative Humidity Temperature Relative Humidity January 70'7 66 59'7 74 +11.0 -8 February 68.7 69 58.5 78 +10.2 -9 March 67.7 73 60.1 80 +7.6 -7 April 68.8 ... 67.2 84 +1.6 ... May 72.1 96 71.6 84 +0.5 +12 June 75.7 97 75.6 84 +0.1 +13 July 78.1 95 81.9 84 -3.8 +11 August 79.2 95 82.1 85 -2.9 +10 September 79.3 88 80.0 79 -0.7 +9 October 77.8 84 74.8 71 +3.0 +13 November 76.2 75 71.0 64 +5.2 +11 December 74.0 68 65.5 72 +8.5 -4

II. METEOROLOGICAL INSTRUMENTS.

Barometers.-The Marvin compensated barometer worked satisfactorily during the year. On January 13 the coil of the combined buzzer and hourly time-mark apparatus was burnt out, owing to the tongue of the relay sticking. When repaired separate coils were provided for the time-mark apparatus and the buzzer, with more satisfactory results.

The station barometer No. 1323 and the large Casella barometer were compared with the Observatory Standard on June 23 and December 3.

Beckley Anemograph.-This instrument was oiled and the orientation of the vane checked once a month.

Dines-Baxendell Anemograph.-This instrument was dismantled on January 14. The cistern was cleaned, fresh distilled water provided and a film of liquid paraffin poured on the water before inserting the float, in order to prevent evaporation inside and outside the float.