156 



Report of the Kew Committee. 



per hour. A reduction of the Robinson factor from 3 to 2' 5 would 

 serve to render the readings of the two instruments more nearly 

 comparable. 



As the Richard instrument is designed to record the velocity of 

 the wind in gusts as well as the total ran during any definite interval, 

 no detailed comparisons with the Robinson indications are possible ; 

 but it may be noted that during the period the cinemograph was 

 under observation gusts of 45 and 43 miles per hour were recorded, 

 whilst simultaneous curve readings of the Robinson gave hourly 

 rates of 55 and 52 miles for quarter of an hour intervals. 



The Munro sight-indicating anemometer is a sensitive Robinson 

 cup arrangement, which drives by means of a small centrifugal pump a 

 column of oil up a glass tube. Its height above a fixed zero mark, 

 as shown on a divided porcelain scale at the side, indicates the 

 velocity of rotation of the cups when converted into miles per 

 hour of wind movement. The divisions of the scale have been laid 

 down in accordance with Mr. Dines' experimental deduction. When 

 the instrument was originally set up, it was found incapable of 

 recording a velocity of more than 40 miles per hour, but, during a 

 gale in November, velocities were attained during several gusts of over 

 70 miles per hour, and. accordingly Mr. Munro has found it desirable 

 to change the gearing of the pump so as to enable the higher values 

 to be indicated. The comparisons with the new gearing are not 

 sufficient in number to furnish results suitable for quotation at the 

 present time, but they appear to show, during gusts, rates fully 20 

 per cent, higher than the cinemograph gives. 



The instrument as fitted at present fails to work during frost, 

 owing to congelation of the oil employed. 



Dr. E. Van Rijckevorsel, of Rotterdam, visited the Observatory in 

 July for the purpose of making simultaneous magnetic observations 

 with the Kew, his own, and the Utrecht unifilar magnetometers, 

 and of comparing the results with those he had recently made with 

 the magnetometers in use at the Observatories at Pare St. Maur, 

 Wilhelmshafen, and Utrecht. 



Professor Rucker has also been investigating the differences found 

 to exist in similar simultaneous readings of his three unifilars ; and 

 his assistants, Messrs. Gray and Watson, have visited Kew on numer- 

 ous occasions in order to make the necessary observations. 



Cloud Photographs. — The operations with the cloud cameras have 

 been conducted during the past year solely according to the simplified 

 method of zenith observation, as described in last year's report, and 

 results were obtained on 24 days. A joint paper by General Strachey 

 and the Superintendent, describing the plan of working, was read 

 before the Royal Society in June, and was fully illustrated by photo- 

 graphs shown m the optical lantern. A report, giving a detailed 



