# Appendix F.
# REPORT OF THE DIRECTOR OF THE ROYAL OBSERVATORY, HONG KONG, FOR THE YEAR 1929.
## I.-GROUNDS AND BUILDINGS.
The grounds were kept in order by the Botanical and Forestry Department with the assistance of Observatory coolies.
A stone for the zero triangulation station was set up by the Public Works Department, 38.5 feet due south of the Observatory transit instrument, on February 2.
The Main Building and the Assistants' Quarters were repainted in the Spring.
The tubular steel storm signal mast on Kowloon Signal Hill having been blown down during the typhoon of August 22 was replaced by a lattice steel mast on November 20.
Magnetic Station at Au Tau.-In view of the large range of temperature in the magnetograph house, during the months of June-August the walls of the inner chamber were covered with sheet asbestos, 1 inch thick, on both inner and outer surfaces. The ceiling and floor were covered on the outer surface only. Interior vestibules were constructed at the entrances of the outer and inner chambers, and it is now necessary to pass through five doors in order to reach the recording room from the outer air. The range of temperature has been sensibly reduced by these alterations, but is still too great. To keep it within the necessary limits, thermostatic control will probably be necessary.
Underground Chamber for Seismographs and Clocks.-The range of temperature in the underground chamber was 9°.7 (F) in 1929 as against 10°.7 (F) in 1928 and 11°.6 (F) in 1927. The relative humidity was never less than 95% between June 6 and September 4. The absolute range during the year was 45% in 1929 as against 45% in 1928 and 61% in 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.