450 



Report of the Kew Committee. 



graph room, to lead the tube of composition metal up through, the 

 entrance hall, and to put up the upper part of glass, with the verniers 

 and divided scales, in the north library in a convenient position for 

 reading. 



It was successfully filled, by Mr. Jordan, with glycerine (coloured 

 red), and has since its erection been read five times daily, simultaneously 

 with the standard mercurial barometer. 



Bog en's Barometers.- — Mr. F. Bogen has deposited two of the patent 

 standard cistern siphon barometers, described by him in the " Quarterly 

 Journal Met. Soc," vol. v, p. 137, in the Observatory, with the re- 

 quest that comparisons might be made between the disk reading and 

 the ordinary method of reading barometers. Mr. Bogen visited the 

 Observatory, on several occasions, to give instructions as to the proper 

 method of filling, setting up, and reading his instruments. 



Mr. Bogen has also submitted for trial an improved Artificial Horizon. 



The De La Rue Evaporation Gauge. — The Vice-Chairman of the Com- 

 mittee has devised a small evaporation gauge, by means of which the 

 water given off: from a continually- wetted sheet of vegetable parch- 

 ment is measured daily. Two of these instruments, constructed by 

 Messrs. ISTegretti and Zambra, are now at Kew, and their indications 

 have been noted every day, at 10 A.M., for the past six weeks. 



The Be La Rue Anemograph. — The Meteorological Council, having 

 now in use Thomson's Harmonic Analyser, instructed the Superin- 

 tendent to again test the anemograph designed by Mr. De La Rue, for 

 the purpose of indicating at once, without replotting, the horizontal 

 movement of the wind from hour to hour. 



The instrument, when tried at the Observatory in 1872, was found 

 to be somewhat defective in its working, as, owing to the mechanical 

 arrangements for returning the pencil to zero, its indications were 

 left unrecorded for intervals varying from three to four minutes every 

 hour. An electrical attachment has now been substituted for part of 

 the mechanism, so as to reduce the time lost to about twenty seconds 

 hourly, and the instrument is at present working in the experimental 

 house. 



The spare Barograph, belonging to the Meteorological Office, is also 

 erected in the experimental house, for the purpose of trying various 

 photographic processes suggested from time to time as desirable 

 substitutes for those now employed in the preparation of the curves 

 for the registering instruments. 



At the request of Professor Stokes, a series of comparisons has 

 been made between a Hodgkinson's Actinometer, returned to England 

 for repair by Mr. Hennessey of Calcutta, and the three standard 

 instruments retained in this country for reference. 



Pendulum Oh sen ations. — The Committee have had their attention 

 directed to an ambiguity in a paper by Messrs. B. Stewart and Loewy, 



