Description of the Kew Observatory. 149 



applications, more prolonged trials on the Greenwich system have 

 been carried out for the Italian and Portuguese Governments. 



Other Miscellaneous Forms. In addition to the above classes of 

 instruments, a considerable variety of other forms have been tested, 

 amongst which may be mentioned barographs, thermographs, air 

 meters, artificial horizons, and rain measures. 



The following table (p. 150) gives particulars as to the numbers of 

 the several forms of instruments which have been examined at the 

 Observatory since 1853. 



Experimental Work. 



In addition to experimental work initiated by the Committee or 

 the Meteorological Office, investigations are carried out at the 

 Observatory on behalf of societies or individuals who have obtained 

 the approval by the Committee of the particular research, and who 

 undertake to defray the expense either from their own private 

 resources or from grants voted by public bodies. 



A long list of original papers bearing on work done at Kew will 

 be found in an appendix to the ' History of the Observatory,' by 

 Mr. R. H. Scott [' Proc. Roy. Soc.,' 1885, pp. 7784 (pp. 4148 of 

 separate off-print)]. Here reference will only be made to a few of 

 the researches and developments which were of special novelty at 

 the time, or have since become intimately associated with the name 

 of the Observatory. 



Self-recording Apparatus. As early as 1843 Sir F. Ronalds, at that 

 time Superintendent, seems to have had a species of self-recording 

 electrometer in regular action. In 1845 he carried out a large num- 

 ber of experiments in photography, and, within a year or two from 

 that date, a barograph and an electrograph, recording photographi- 

 cally, appear to have been in use. In 1851 a six months' trial of a 

 photographic magaetograph was in progress. The present Kew 

 pattern magnetograph is a modification erected in 1856 by Mr. Welsh, 

 Sir F. Ronalds' successor. 



Balloon Ascents. In 1852 Mr. Welsh made several balloon ascents, 

 in which a large number of meteorological observations were taken at 

 different heights up to 22,000 feet ( 4 Phil. Trans.,' 1853, p. 311). 



Sun-spot Observations. In 1856 the photoheliograph was erected, 

 and the observations of sun-spots, &c., made with it, formed the basis 

 of a number of papers by Mr. De la Rue, Professor Balfour Stewart, 

 and others in the ' Phil. Trans.,' ' Proc. Roy. Soc.,' ' Phil. Mag.,' &c., 

 from 1565 onwards. 



Atmospheric Electricity. In 1861, the water-dropper invented by 

 Lord Kelvin then Professor William Thomson came into operation, 

 and in 1868 the results on Atmospheric Electricity obtained with it 



