42 



Report of the Kew Committee. 



the Boyal Gardens, Kew, likewise at the expense of Mr. De La Rue*. 

 This is being photographed by the Kew Photoheliograph for the purpose 

 of determining the optical distortion (if any) of that instrument, in 

 order to furnish the final corrections to the reductions of the sun-pictures 

 made with it. 



A Heliograph for Pulkowa has been placed in the Dome, and photo- 

 graphs have been taken of the scale in order to determine its optical 

 character. This instrument has since been removed; but the stages and 

 preparations for future instruments remain in situ, and will be used for 

 testing the other instruments to be employed for the observations of the 

 transit of Venus. 



Since March, when the sun-photograms were discontinued, eye obser- 

 vations of the sun, after the method of Hofrath Schwabe, have been made 

 with a telescope of 2| inches aperture (lent by Sir E. Sabine) by Mr. 

 Foster, in order that the observations for connecting sun-spots with 

 magnetic phenomena might not drop through until photographic records 

 are taken up on a permanent footing. 



Electrometer. — This instrument, designed by Sir W. Thomson, P.B.S., 

 was provided by the Meteorological Committee in 1869, but has never 

 been systematically in operation. It was dismounted early in the year, 

 in order to be removed to another position. Previous to its re-erection 

 some modifications are required; and accordingly, on a recent visit to 

 London of the maker, Mr. White, of Glasgow, that gentleman came 

 down to Kew (September 28) and removed a considerable portion of the 

 apparatus in order to effect the necessary alterations at home. 



Verifications. — This department of the Observatory has been in full 

 activity during the year. The following Magnetic Instruments have been 

 verified to obtain new constants : — 



A Unifilar for the North- American Boundary Commission. 



A Unifilar, a Dip-circle, and Pox's Instrument, for HJVi.S. ' Challenger,' 

 the first two having been formerly used on board H.M.S. ' Nassau.' 



* Disbursements by Mr. Warren De La Rue from February to October 31, 1872 : — 



£ s. d. £. s. d. 



Paid to Mr. Loewy for measuring and reducing the position of 



spots to the end of October 75 



Mr. Whipple for area measurements 20 



95 



Mr. Munro for Scale 30 7 6 



Mr. Jeffery for erection of the Scale 20 



50 7 6 



Mr. Whipple for Chemicals 10 



,, Photographing Scale 5 



Mudd and Son for experiments with Dry Plates 2 3 6 



Mr. T. Coleman for Photographic Printing 15 6 



17 19 



1-163 6 6 



