REPORT OF THE KEW COMMITTEE. XXXIU 



During the past year eight Sextants, two Quadrants, and one Transit- 

 instrument have been verified. 



The sun-spots continue to be observed, after the method of Hofrath 

 Schwabe, of Dessau. 



The Kew Heliograph in charge of Mi-. De la Rue has been continuously 

 worked by a qualified assistant, under the immediate supervision of Mr. 

 Beckley, who has proved of mucli service to the Committee in this as well as 

 in other matters. During the past year 175 negatives have been taken, and 

 four sets of positives have beeu printed from each, one of which has been 

 presented to the Eoyal Society. The negatives are being reduced under the 

 superintendence of Mr. De la Eue, and by means of an instrument of his 

 construction. Mr. B. Loe^v}% formerly assistant in the Flagstaff Observatory, 

 Melbourne, has been engaged in this reduction, which he is executing very 

 satisfactorily at Kew. 



Mr. De la Eue is also having an arrangement made, by means of which 

 the proportion of the sun's disk obscured by spots may be conveniently 

 measured. 



At Mr. De la Rue's request Mr. Loewy is now examining all pictm-es 

 preserved at Kew, with reference to distribution of faculae and general ap- 

 pearance, and it seems that, out of more than 500 groups hitherto examined, 

 about 250 show a nearly equal distribution of faculous matter round the 

 penumbra, while of the rest more than 200 have the faculoe decidedly, 

 cither entirely or mostly, on the left side. After concluding the examination, 

 which will extend over more than 1000 spots, Mr. Loewy will submit the 

 result to Mr. De la Rue. 



The Spectroscope belonging to the Chairman has been supplemented with 

 a set of eleven sulphuret-of-carbon prisms, made by Mr. Browning, and 

 giving the very great angular separation of more than 3' between the two 

 lines D. The Chairman has communicated a short description of these prisms, 

 and of the appearance of the two lines obtained by this arrangement, to the 

 Royal Society. 



That portion of the spectrum between D and E is now being mapped, 

 and all the measurements have already been made. The results obtained 

 show that the position of any line can be determined with very great accu- 

 racy. Mr. Loewy has been the principal observer, and he seems well quali- 

 fied for the work. 



Preliminaiy arrangements have been made, under the superintendence of 

 Professor Stokes, for experiments on the retardation of the pendulum in 

 different gases. 



At the request of the Secretary of State for India, received tkrough the 

 Royal Society, arrangements have been made for the preparation of appa- 

 ratus to be used for the vibration of i^endulums in vacuo at the different 

 stations of the Trigonometrical Survey in India ; and the request has also 

 been made that the officer who may conduct this experimental investigation 

 should receive instructions at this Observatory. 



The instrument constructed by Mr. Broun for the purpose of estimating the 

 magnetic dip by means of soft iron remains at present at the Observatory. 



The balance of the ^40 granted by the British Association in 1861, for an 

 additional photographic assistant, has been expended under the superin- 

 tendence of Mr. De la Rue, along with fiu'ther sums which have been defrayed 

 by Royal Society grants received by that gentleman. 



The Superintendent has likewise received grants from the Royal Society 

 for special experiments to be made at Kew, and when these are completed 



1S64. c 



