Description of the Kew Observatory. 151 



were discussed by Professor Everett (' Phil. Trans.' for 1868, p. 347, 

 and elsewhere). A more recent discusssion by the late Superinten- 

 dent, Mr. Whipple, occurs in the ' B.A. Report ' for 1881, p. 443. 



Terrestrial Magnetism. In 1859 71 General Sabine, the then 

 Chairman of the Kew Committee, contributed to the Royal Society 

 a number of papers based on the Kew magnetograph results, dealing 

 inter alia with the phenomena of magnetic storms. 



Therm ometry. In 1863 Professor Balfour Stewart, then Superin- 

 tendent, made a large number of experiments with the air thermo- 

 meter ('Phil. Trans.,' 1863, pp. 425435). He found for the 

 mean coefficient of expansion of air between and 100 C. the value 

 G'0036728, while for the freezing point of mercury on the scale of 

 the air thermometer he found 37'93 F. or 38'85 C. 



Pendulum Observations. In 1865 experiments were made by 

 Captain Basevi with pendulums, subsequently used for geodetic 

 work in India. Similar experiments have since been carried out 

 on several occasions (see General J. T. Walker in the ' Phil. Trans.' 

 Series A, for 1890, p. 537). 



Variations of Temperature, <^c., with Height. During the years 

 1873-4-5 an extensive series of experiments were conducted for the 

 Meteorological Office on variations of temperature and humidity with 

 height above the ground. Thermometers were exposed in screens 

 of the same pattern at three different heights, the highest 129 feet 

 from the ground, on the ornamental pagoda in the Royal Gardens, 

 Kew, the requisite permission having been obtained from H.M. 

 Office of Works and the Director of the Gardens. Throughout the 

 greater part of the time readings were taken thrice daily. The 

 results, and their relation to those deduced from a similar research 

 made by Dr. Wild at Pulkowa, were discussed by Mr. R. H. Scott 

 (' Quarterly Weather Reports of the Meteorological Office,' 1876, 

 A PP .,pp. [20]-[37]). 



Anemometry. In 1874, at the suggestion of Mr. R. H. Scott, a 

 series of comparisons were made of anemometers of different pat- 

 terns. The principal experiments were carried out at the Crystal 

 Palace by Mr. Jeffery and Mr. Whipple, the instruments being 

 mounted on a steam merry-go-round. This was driven at various 

 velocities up to 30 miles an hour. The bearing of the results on the 

 questions of the existence and magnitude of a constant "factor" for 

 the Robinson cup anemometer was discussed by Professor Stokes in 

 1881 ('Roy. Soc. Proc.,' vol. 32, p. 170). 



Cloud Measurements. In 1885, after numerous preliminary experi- 

 ments which originated in 1878, two cameras were erected, one on 

 the Observatory roof, the other at a horizontal distance of 800 yds., 

 and a series of observations begun to determine the heights and 

 velocities of clouds. The original observations dealt with clouds at 



