66 Notes of Observations with 



On the 22nd, 25th, 26th, 27th, 28th, 29th, and 81st Aug., 

 the comet was observed and a number of differential places 

 obtained with the Great Telescope, some also with the small 

 equatorial refractor. The weather then again broke up, and 

 as the comet set early, or rather became toD low for observa- 

 tion, and had not risen sufficiently to observe before daylight 

 in the morning, no fair chance of seeing; it again occurred 

 until the 14th Sept., when it was searched for without 

 success, the evening not being good. On the 15th I again 

 found it .and obtained a number of differential readings by 

 means of the Grubb micrometer and the chronograph. On 

 the 20th and 21st, the comet appearing exceedingly faint and 

 aurora interfering I obtained a number of similar differential 

 readings, but the position became continually worse for 

 observation. On the 27th Sept. it was again with difficulty 

 observed, and on the 11th Oct. the last glimpses of this 

 visitor were obtained only by sweeping the telescope rapidly 

 over its computed place and so gaining the effect of quick 

 contrast with the sky ; but, of course, no differential place 

 could be recorded. The great light-collecting power of a 

 4 ft. aperture, however, showed to great advantage in these 

 observations ; by which the object was followed for a month 

 longer than was possible to the other instruments available 

 at the Observatory. 



Moon. — One half of each lunation being lost for the 

 purposes of work upon the nebulae — the special work of the 

 great equatorial, owing to the quantity of diffused moonlight 

 which obliterates nebular details, I have endeavoured, as 

 much as possible, to utilise these moonlight evenings by 

 devoting such part of them as can be spared from public 

 visitors to occasional work upon the moon itself, the planets, 

 and double stars — conducted under some difficulty, as no 

 means have been yet provided for screening the eye from 

 the painful glare of the moon, or for reducing or altering 

 the shape of aperture to obtain clear definition and ease to 

 the eye for micrometer measurements. But I give a few 

 extracts which may prove interesting. 



Copernicus. — 2nd Dec, 1870 — TerTninator (or line of 

 sunrise), 50 miles beyond Copernicus, which has four central 

 peaks nearly on lunar parallel ; the two most easterly close 

 together. Several other peaks of inferior altitude appear 

 under higher illumination, the whole group standing on a 

 floor which gradually rises from the foot of the interior slope 

 of the vast ring 50 miles in diameter. Seven or eight consecu- 



