466 



Report of the Kew Committee. 



The new Cathetometer has received some slight additions tending to im- 

 prove its usefulness. 



One Theodolite, three Sextants, and a Clinometer have been veri- 

 fied. 



Experiments have been made with the new Deep-sea Sounding Ther- 

 mometer, invented by Messrs. Negretti and Zambra ; and the Committee 

 have under consideration the construction of an apparatus for the pur- 

 pose of verifying this class of instrument under varying hydraulic 

 pressure. 



A system has also been organized for etching a " Hall-mark," 

 as in the annexed figure, upon all Thermometers which have 

 been verified. A pantagraph has been purchased for the 

 purpose of engraving this marls and a register number upon the instru- 

 ments. 



The old " Eoyal Society " Standard Barometer, constructed by Newman 

 in 1837, under the direction of Mr. Baily, which has been in a defective 

 condition since its removal from the Society's Booms in Somerset House 

 in 1857, having been lent to the Kew Committee by the Council of the 

 Eoyal Society for one year, has been thoroughly repaired and both its 

 tubes refilled, and is now erected at the Observatory, with a view of 

 making a lengthened series of comparisons with the two normal Baro- 

 meters of the establishment. 



Comparison of Standard Barometers. — The Astronomer Eoyal having 

 courteously offered the Committee every facility for a suggested compari- 

 son between the Greenwich and Kew Standard Barometers during April 

 and May last, a number of carefully selected Portable Standard Baro- 

 meters were conveyed to and fro between Greenwich and Kew on three 

 separate occasions, and a large number of comparative readings were 

 obtained by the Superintendent and Messrs. Baker and Foster. 



A complete detailed account of the experiment has been drawn up, and 

 will be laid before the Eoyal Society. 



A determination has been made of the daily range of the Thermometer 

 at Kew for the past twenty-one years, viz. 1855-75, inclusive. The 

 results have been discussed by Prof. Balfour Stewart, and embodied by 

 him in a paper " On the Variations of the Daily Eange of Atmospheric 

 Temperature as recorded at the Kew Observatory," Proc. Eoy. Soc. 

 vol. xxv. No. 178. 



Meteorological data have been supplied, among others, to Mr. G-. J. 

 Symons, the Secretary of the Northern Institute of Mining Engineers, 

 the Secretary of the Midland Institute, and the Editors of ' The Times ' 

 and ' Illustrated London News.' 



Pendulum Experiments. — The apparatus specified in the Eeport for 

 1875, as granted by the Committee to the Hydrographer for the service 

 of the Arctic Expedition, was returned to the Observatory shortly after 

 the arrival home of the vessels ; but no observations having been made 



