Appendix F.
REPORT OF THE DIRECTOR OF THE ROYAL OBSERVATORY, HONGKONG, FOR THE YEAR 1924.
1.-GROUNDS AND BUILDINGS
The grounds were kept in order by the Botanical and Forestry Department with the assistance of the Observatory coolies.
Underground Chamber for Seismograph and Clocks.--As the scale value of the thermograph supplied by Messrs. Short and Mason was too small for satisfactory registration of the minute changes of temperature in the Underground Chamber, magnifying levers were constructed and fitted by Mr. Evans. In October, after several trials, with levers of various dimensions, counter-poised and uncounterpoised, and the introduction of a buzzer, he succeeded in obtaining satisfactory registration with a scale value of 0.6 inch to 1°C. The buzzer is fixed on a brass frame screwed to the supports of the dry and wet bulb thermometers. It is operated for 1 sec. every minute. Such high magnification is only feasible in conjunction with a buzzer, or other device for overcoming the combined effects of inertia and friction.
The records are standardized by 4-hourly readings of dry and wet bulb thermometers, graduated to 0.1°C and read to 0.01°C by estimation. They show that the diurnal inequality of temperature in the Underground Chamber is small, but greater than indicated by the thermograph in its original condition.
In the following table the mean temperature of the air and humidity, at 4-hourly intervals, for November and December, 1923, are compared with the corresponding figures for 1924 :-
Month and Year 0h. 4h. 8h. Noon. 16h. 20h. Range. Nov. 1923 75.28 75.23 75.24 75.25 75.27 75.23 0.05 Nov. 1924 76.23 76.23 76.23 76.15 76.25 76.32 0.17 Dec. 1923 72.72 72.64 72.63 72.66 72.68 72.68 0.09 Dec. 1924 72.93 72.82 72.86 72.90 72.88 72.95 0.13Temperature of air in Underground Chamber.