REPORT OF THE KEW COMMITTEE. XXH 



The following statement shows the number of meteorological instruments 

 which have been verified at Kew during the past year : — 



Thermo- Baro- Hydro- 

 meters, meters, meters. 



For the Admiralty and Board of Trade .... 360 90 100 



For the Portuguese Government 12 



For Opticians and others 170 35 



Total 530 137 100 



On February 5, the Committee resolved, — " That, in consideration of the 

 number of Barometers already verified at Kew having been sufficient to 

 defray the preliminary expense of apparatus, the charge for verification shall 

 in future be reduced to five shillings each instrument." 



Arrangements have been made with Messrs. Adie, Casella, and Negretti 

 and Zambra, to have on hand a constant supply of verified marine meteoro- 

 logical instruments, and the Public may be supplied through any respectable 

 Optician in London or the country at the following prices : — 



For a Marine Barometer £4; 4 



For a Set of Six Thermometers 2 2 



Since the last Report, the Committee have disposed of 60 standard ther- 

 mometers, graduated at the Observatory. Of these, 14 have been made for 

 Mr. Hopkins, to be employed in his experiments on the eff"ect of pressure 

 upon the melting-points of solids. The charge on account of the graduation 

 and distribution of these thermometers is arranged with the Government 

 Grant Committee of the Royal Society, and consequently does not appear in 

 the financial accounts of the Kew Committee. 



A self-recording Anemometer, for measuring the velocity of the wind on 

 the plan of Dr. Robinson, has been completed at the Observatory by Mr. 

 Beckley : it is erected upon the dome, and has been in regular operation since 

 the 1st of January. Its performance is most satisfactory, the delicacy of its 

 indications being so great, that during the last six months the whole period 

 of "calm," as shown by the registrations, has been only fotir hours. It has 

 not yet been possible to erect an apparatus for registering the direction of 

 the wind, on account of difficulties arising from the anticipated use of the 

 dome for the solar photographic telescope. The direction of the wind has, 

 however, been observed five times daily from an ordinary vane. 



Mr. Beckley has since submitted to the Committee a model of a new 

 arrangement for a self-recording Anemometer, in which the registration of 

 both the direction and velocity of the wind (and also the fall of rain if 

 desired) is obtained upon a single sheet of paper. This arrangement is much 

 more compact in its design and less costly in construction than any other 

 with which the Committee are acquainted. Mr. Beckley 's model will be 

 exhibited, and a description of it communicated to this Meeting. 



A series of monthly determinations of the absolute horizontal force and 

 of the magnetic dip was commenced in January, with instruments provided 

 by General Sabine from his department at Woolwich. Some difficulties 

 have been experienced by Mr. Welsh in the observations of the absolute 

 horizontal force, owing to imperfections in the usual mode of suspension of 

 the magnets during the observations of vibration. These difficulties he 

 hopes soon to overcome by employing reversible collimator magnets, and by 

 an improved mode of suspension. 



