REPORT OF THE KEW COMMITTEE. IvU 



meanwhile tapped so as to imitate as well as possible the tapping by the 

 hand which these instruments are usually subjected to previously to the read- 

 ings being taken. 



These experiments show that, while Aneroids cannot be considered equal 

 in accuracy to standard Barometers, yet the best-constructed Aneroids, within 

 certain limits, give reliable results. 



3. Photoheliograph. — The Kew Heliograph, in charge of Mr. De la Eue, 

 continues to be worked in a satisfactory manner. During the past year 204 

 negatives have been taken, on 144 days. Pictures of the Pagoda in Kew 

 Gardens are regularly taken by this instrument, in the hope that by this 

 means the angular diameter of the Sun may be satisfactoiily determined. 

 Since the last Meeting of the Association, a second scries of solar researches, 

 in continuation of the first series, has been published (the expense of print- 

 ing having been defrayed by Mr. De la Eue), entitled " Eesearches in Solar 

 Physics, Second Series, Area Measurements of the Sun-spots observed by 

 Mr. Carrington during the seven years 1854-1860 inclusive, and deduc- 

 tions therefrom. By Messrs. De la Eue, Stewart, and Loewy." 



The Heliographic latitudes and longitudes of all the spots recorded by the 

 Kew Photoheliograph during the years 1862 and 1863 have been calculated, 

 and it is hoped that the results may soon be published, forming a thii'd 

 series of Solar Eesearches. It is believed that these results will demon- 

 strate the superiority of photographic pictures over all other methods of 

 observation. 



The sum of <£60 has been obtained from the Government Grant fund of the 

 Eoyal Societj', to be applied to the discussion of Hofratli Schwabe's long and 

 valuable series of Sun-spots, at present in the possession of Kew Observatory. 

 These pictures are now being examined with this object. 



Sun-spots continued likewise to be numbered after the manner of Hofratli 

 Schwabe, and a table exhibiting the monthly groups observed at Dessau and 

 at Kew for the year 1866 has already appeared in the Monthly Notices of the 

 Astronomical Society, vol. xxvii. No. 3. 



4. Ajyparatus for verifying Sextants. — The apparatus constructed by 

 Mr. Cooke, for verifying Sextants, has for some time been erected at the 

 Observatory ; and a description of it has been communicated by Mr. Stewart 

 to the Eoyal Society, and published in their ' Proceedings,' vol. xvi, p. 2. 



Seven Sextants have been verified during the past year. 



5. MisceUaneous worJc. — The preliminaiy observations with Captain Kater's 

 pendulum, alluded to in last year's Eeport, have been made ; but the reduc- 

 tions are not yet quite finished. 



An account of certain experiments on the heating of a disk by rapid rota- 

 tion in vacuo has been communicated to the Eoyal Society by Mr. Stewart 

 in conjunction with Professor Tait, and has been published in the 'Pro- 

 ceedings ' of that body. 



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

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

 awaiting Mr. Brouu's return to England. 



During the past year two standard yards for opticians have been compared 

 with the Kew standard. 



Several instruments, chiefly magnetic, have been sent to Kew by General 

 Sabine from his office at Woolwich. 



The Superintendent has received grants from the Eoyal Society for special 

 experiments ; and when these are completed an account will be rendered to 

 that Society. 



