504 Report of the Kew Committee. 



IV. EXPERIMENTAL WORK. 



Fog and Mist. The observations of a series of distant objects, 

 referred to in the last Report, have been continued. A note is taken 

 of the most distant of the selected objects which is visible at each 

 observation hour. An analysis of the results for the period May, 

 1892, to December, 1893, has been prepared and forwarded to the 

 Meteorological Council. 



Electrical Anemograph. At the instance of the Meteorological 

 Council the electrical anemograph referred to in the Report for 

 1890, with an improved arrangement for recording wind direction, 

 has been under trial for some months. 



Atmospheric Electricity. To throw light on the results obtained 

 with Lord Kelvin's water-dropper, a series of observations have 

 recently been made for the Meteorological Office on the distribution 

 of electric potential in the neighbourhood of the Observatory. 



Aneroid Barometers. A grant of 30 has been obtained from the 

 Government Grant Committee for the purpose of conducting a research 

 on the behaviour of aneroid barometers. The work of constructing 

 the air pump and other apparatus required was entrusted to Mr. J. 

 Hicks. He has unfortunately experienced considerable mechanical 

 difficulties, which have delayed the construction of the apparatus. 

 It is hoped, however, that it will be ready for use at an early date. 



Thermometry. Experiments are proceeding with a view to facili- 

 tate, and put on a more certain basis, the " time-test " in clinical 

 thermometers i.e., the measurement of the time required by a 

 thermometer to record the temperature of the body. 



A sub- committee is now considering the question of the degree of 

 accuracy to be aimed at in the comparison of thermometers, the 

 form and construction of Kew Standards, and the advisability of 

 supplying on the certificate forms fuller information than is given at 

 present. 



Lens Testing. A large number of experiments have been made for 

 the purpose of devising a photographic object for the definition test 

 of lenses, which will supply more certain results than those hitherto 

 obtained. A photographic object, reduced by Messrs. Morgan and 

 Kidd, has given some fairly satisfactory results ; but it. is hoped a 

 still further improvement may be effected by means of an object, 

 suggested by Major Darwin, which is about to be constructed. 



V. VERIFICATION OF INSTRUMENTS. 



The subjoined is a list of the instruments examined in the year 

 1894, with the corresponding results for 1893 : 



