328 



Report of the Kew Committee. 



IV. Experimental Work. 



In accordance with the request of Mr. Ellery, the Government 

 Astronomer at Melbourne, the Indian pendulum apparatus, having 

 been thoroughly overhauled since its return from the Royal Observa- 

 tory, Greenwich, to Kew, was carefully packed and shipped to 

 Melbourne, for use in the Gravity Survey now being undertaken by 

 the Australian authorities. 



The packing and shipping were conducted under the direction of 

 General Walker, who prepared a detailed statement of the necessary 

 instructions to be followed by the observers. 



The Richard thermograph, procured for use with the apparatus, 

 was also carefully packed and sent to Melbourne. Notice has been 

 received of the arrival in the Colony of the apparatus. 



Cloud Photographs. — Operations connected with cloud photography 

 have been suspended during the past year. At the request of the 

 Meteorological Office, certain cloud negatives taken in 1891, with 

 their reductions, were forwarded to them for examination, as well as 

 the apparatus used in the reduction of their heights and velocities. 



Fog and Mist. — With the view of ensuring greater uniformity in 

 observations of these phenomena, at the suggestion of Mr. R. H. 

 Scott, a list of twenty-four well-known objects in the neighbour- 

 hood of the Observatory has been prepared, at distances varying 

 from 9 to 3850 yards. Since May, the most distant of the objects 

 visible at each observation hour between sunrise and sunset has been 

 noted. Up to the present the most dense fog recorded was when an 

 object at 20 yards distance was obscured: 



Further experiments were made at the beginning of the year with 

 Munro's sight indicating anemometer, but the variation of viscosity 

 of the oil at low temperatures has caused some difficulty in deter- 

 mining the scale value of the instrument, which has been returned to 

 the maker. 



V. Verification of Instruments. 



The following instruments have been purchased on commission and 

 their constants determined : — 



1 pair of dip needles, for the Meteorological Institute, Copen- 

 hagen. 



1 pair of dip needles for the Imperial and Royal Austro-Hungarian 

 Embassy, London. 



1 Clifton electrometer, water dropping collector and insulators, also 

 a battery of 60 chloride of silver cells and a dip needle for the Royal 

 Alfred Observatory, Mauritius. 

 * A set of 24 thermometers fcr the Observatory, Hong Kong. 



