Report of the Ken: Committee. 



449 



inversely as the barometric pressure between the limits of 29'0 and 

 3>3 inches, the variation being most rapid between 29 - 8 and 30*1 

 inches. Also that above 30' 3 inches cloud increases with increasing 

 pressure, attaining the mean about 30' 5 inches, and rising above it at 

 30*6 inches. 



Various experiments have been made with the sunshine-recorder 

 from time to time with the view of improving its efficiency, and new 

 instruments with certain modifications of the Kew pattern have been 

 submitted for approval by Messrs. Beck and Mr. Casella. 



Wind Component Integrator. — The nnmerons adjustments and elec- 

 trical contacts, altogether 190 in number, of this instrument, render 

 it particularly subject to derangement in this country, the damp 

 atmosphere causing frequent failures in the electrical actions, and the 

 high winds constantly shaking the screws loose. The continual neces- 

 sity for readjustment causing a greater demand upon the time of the 

 Observatory staff than the Committee feel themselves justified in 

 bestowing upon it. they have reluctantly decided upon dismounting 

 it, and it will shortly be returned to South Kensington, to be again 

 set up in the Loan Collection of scientific apparatus. 



Photo-nephoscope. — At the request of the Meteorological Council this 

 instrument, which was mentioned in the last Report, was, in March, 

 placed in the hands of Captain Abney, R.E., E.R.S., that gentleman 

 having kindly offered to make some experiments with it. 



Exposure of Thermometers. — Experiments have been for some time in 

 progress at the Observatory with the view of determining the relative 

 merits of different patterns of thermometer screens. For this purpose 

 there have been erected on the lawn a Stevenson's screen, of the ordi- 

 nary English pattern, and a large wooden cage, containing a Wild's 

 screen, of the pattern employed in Russia. Each of these screens con- 

 tains a dry and wet bulb thermometer, and a maximum and minimum, 

 all of which are read daily at 9 A.M. and 9 p.m., their indications being- 

 compared with those of the thermograph at the same hours. A third 

 portable metal screen, designed by Mr. De La Rue for use on ship- 

 board, which contains a dry bulb thermometer only, is also carried out 

 by the observer, and read at the same time as the fixed instruments. 



The cost of these experiments is borne by the Meteorological Council. 



Glycerine Barometer. — Mr. J. Jordan, having obtained a grant from 

 the Government Fund of the Royal Society for the construction of a 

 glycerine barometer, applied to the Committee for permission to erect 

 it in the Observatory. This they willingly granted, and they also 

 undertook to read it regularly for one year. It has accordingly been 

 set up in the building, but owing to its great length, thirty feet, some 

 difficulty was experienced in finding a suitable situation for it. 

 Eventually it was decided to fix the cistern (which was first ascer- 

 tained to be constructed of non- magnetic materials), in the magneto- 



