350 Report of the Kew Committee. 



Nocturnal Radiation. — Professor Tyndall having suggested the 

 desirability of making a series of experiments on the fall of tem- 

 perature near the surface of the ground at the time of sunset, a 

 scheme was organised and apparatus devised by Mr. F. Galton, by 

 means of which thermometers suspended at heights of 2 feet, 4 feet, 

 and 20 feet could be rapidly read and their indications compared with 

 those of a thermometer placed on swans' down on the surface of the 

 ground. 



The apparatus employed is conveyed into the open park to some 

 distance from any building or trees, and the thermometers read at five- 

 minute intervals from about half-an-hour before sunset until one or 

 two hours after. 



The cost of these experiments will be defrayed by a grant from the 

 Meteorological Council. 



V. Verification of Instruments. 



The following magnetic instruments have been verified, and their 

 constants have been determined : — 



1 Unifilar Magnetometer for Negretti and Zambra. 



2 Unifilar Magnetometers for Elliott Brothers. 

 2 Dip Circles for Elliott Brothers. 



1 Dip Circle for Casella. 



There have also been purchased on commission and verified : — 



A Unifilar Magnetometer for the Toronto Observatory. 

 A Unifilar Magnetometer for the Zi Ka Wei Observatory, 

 China. 



2 Dip Circles, with tripod stands, for Dr. Neumayer, Hamburg. 

 1 Dip Circle, with tripod stand, for Professor Brioschi, Naples. 

 1 ,, „ for M. Snellen, Utrecht. 



1 ,, „ for Dr. Hann, Vienna. 



1 „ „ for Dr. Wild, St. Petersburg. 



1 ,, „ for Professor Nordenskiold, Helsingfors. 



A Vertical Force Needle for Dr. Viegas, Coimbra. 



A Deflection Bar and Pair of Magnetizing Bars for Dr. Rijke- 



vorsel, Rotterdam. 

 A Pair of Dip-circle Agates for Senhor Capello, Lisbon. 



The number of meteorological instruments verified continues still to 

 increase, having been in the past year as follows : — 



Barometers, Standard 48 



,, Marine and Station 105 



Aneroids 30 



Total 



183 



