OBSEKVATOPJES AND INSTRUMENTS. 



679 



tions have also been made with a view to defin- 

 ing the position of the ecliptic and the sun's 

 place in it, and upon the moon. No important 

 changes, instrumental or otherwise, have hero 

 been lately (up to July, 1865) introduced. An 

 arrangement, however, is in successful oper- 

 ation by which the Observatories of Greenwich 

 and Paris are each charged with the meridional 

 observations of the asteroids during half of 

 each lunation tho former from new to full 

 moon, the latter from full to new : in this way, 

 without involving incompleteness in the work, 

 relief is afforded to both these establishments. 



At the 35th meeting of the British Associ- 

 ation for the Advancement of Science, which 

 opened September 6, 1865, Mr. J. P. Gassiot, 

 chairman of the " Kew Committee," presented 

 a full report, from which a few particulars will 

 here be noted. Capt. Basevi and Col. Walker, 

 of the Indian Trigonometrical Survey, had re- 

 ceived instruction at the Kew Observatory, 

 with a view to making the pendulum experi- 

 ments in India which the Association had pre- 

 viously ordered. The two pendulums to be 

 used, both previously employed by Sabine, and 

 one by Airy, in important experiments, after 

 having their constants determined anew, had 

 arrived in safety at the office in India of the 

 survey, in charge of Mr. J. Hennessey. 



By the Kew Heliograph, under the supervis- 

 ion of Mr. Warren De la Rue, 243 negatives 

 (photographic) of the sun had been taken on 

 146 days, and four sets of positives printed from 

 these had been distributed among men of sci- 

 ence. An addition has been made to the mi- 

 crometer, by means of which the proportion 

 of the sun's disc at any time obscured by spots, 

 can be measured, Mr. Carrington has placed 

 at the disposal of this Observatory his original 

 plates, 166 in number, representing observations 

 of sun-spots made during seven years at his 

 Observatory at Redhill. In order that all ob- 

 servers who desire may be enabled to investi- 

 gate the phenomena of solar spots, it has been 

 thought proper to publish the results in such a 

 way that any one may study their appearance 

 and behavior ; and to this end, a lens is being 

 made by Dalmeyer, intended to magnify groups 

 of spots to a scale on which the sun's diameter 

 shall equal two feet. Kew having been the 

 first public institution to take up the obser- 

 vation of sun-spots after the manner of M. 

 Schwabe, of Dassau, has procured from that 

 astronomer the full set of original drawings of 

 the sun's surface, etc., made by him during 

 about forty years. 



A large number of instruments for meteor- 

 ological purposes, including a self-recording 

 barograph and thermograph, barometers, ther- 

 mometers, etc., had been during the preceding 

 year verified at this observatory, for use in 

 other institutions of the sort and by private 

 observers. At Kew, a self-recording barograph 

 is in constant operation, and duplicates of tho 

 traces recorded in the instrument are obtained, 

 one set of which has been forwarded to the 



meteorological department of the Board of 

 Trade. The photographic action of total day- 

 light is daily registered by an apparatus con- 

 structed by Prof. Roscoe, and in accordance 

 with his request. Of this Observatory Mr. Ral- 

 fbur Stewart is director, while the meteorolog- 

 ical department is in charge of Mr. Thomas 

 Baker. 



An account, at considerable length, of the me- 

 teorological system in operation in Great Britain, 

 including weather " forecasts"and storm-signals, 

 and the establishing of which was so largely due 

 to the labors of the late Admiral R. Fitzroy, will 

 be found under METEOROLOGY, in the volume 

 of this CYCLOPEDIA for 1862. It appears, how- 

 ever, that at the present time the meteorolog- 

 ical systems in operation in France and Russia 

 are much in advance of the English ; and it 

 has recently been urged that in the latter coun- 

 try the Board of Trade should adopt the -con- 

 tinental plan of daily published bulletins, to 

 which might also be added charts or notices of 

 the progress of important agricultural labors, 

 of blights, epidemics, etc. At Mr. De la Rue's 

 observatory, at Cranford, during the year 1863, 

 several fine lunar photographs were taken, some 

 of the negatives being enlarged with success to 

 the dimensions of Beer and Madler's map, 38 

 inches. The silvered-glass mirror received from 

 Dr. Steinheil, of Munich, was to be tried, its 

 light being considerably greater than that of 

 speculum-metal mirrors, and so much so as to 

 give hope that the time of exposure could be 

 shortened. The mirrors had so far preserved 

 their original polish, the precaution having 

 been taken to insert lime-boxes in the tube 

 of the telescope, to prevent their becoming 

 damp. 



At the Ely Observatory, the Rev. W. Selwyn 

 has had in operation since January 1, 1863, an 

 instrument termed a heliautograph, and con- 

 sisting of a photographic camera attached to a 

 Dollond retractor of two and three-quarters 

 inches diameter. During the year sun-pictures 

 were taken on 139 days. Two of these afford 

 interesting records of the solar eclipse of May 

 17, 1863; the latter of them, taken near the 

 middle of the eclipse, shows very distinctly the 

 uneven edge of the moon on the solar disc, and 

 the appearance (so often noticed, and now gen- 

 erally believed an optical effect) of a bright 

 band surrounding the edge of the moon. Mr. 

 Selwyn's pictures are of about four inches 

 diameter, and, as recording the phenomena of 

 the formation and changes of spots (a second 

 picture having for this purpose been, on each 

 of 55 days, taken after a short interval), and in 

 particular for the good view they afford of the 

 facute, will prove a valuable supplement to the 

 Kew photographs. A larger refractor, of six 

 inches aperture, was being prepared for the 

 work now indicated. 



Mr. Cooke, of London, is engaged in the con- 

 struction of a refracting telescope of very un- 

 common dimensions. The aperture of tho 

 object-glass is 25 inches ; focal length 29 feet. 



