and Astronomical Notices. 187 



ought ; my daylight measures I find to be decidedly smaller than 

 those by lamplight : the difference being "'20 or "'25 ; the same was 

 doubtless the case at Poona, with the five foot, and it was from not 

 being conscious of this, that I was thrown out in my first orbit — the 

 last measures being nearly all daylight ones, there appeared to be a 

 rapid change of curvature in the path ; whereas in fact the altera- 

 tion has not become clearly sensible up to the present moment. 

 There is much difficulty in accounting for this, and it may have 

 something to do with the false light and colours arising from the re- 

 fraction causing the centre of figure of each image to be different 

 at night from what it is by day, when the false light is cut off. As 

 the small star is always (apparent) uppermost here at the time of 

 observing, the error in distance arising from this cause would have 

 a constant sign ; and if this be true, the error will change its sign 

 when the stars change quadrants, as they will in about two years at 

 furthest. 



*' The climate of Madras," he adds, " seems as bad for observing 

 as the English, for there is nearly as much cloudy weather ; and 

 where there is a ludd interval, one feels perhaps so exhausted by 

 the heat, and utterly worn out, as to be unable to take full advan- 

 tage of it. But at Poona, if one did miss a clear night from any 

 cause, it mattered little, as one was pretty sure that the next and 

 the next, and the next, would be equally good. I am just now 

 starting for the Nilgiri hills, to look after the small meteorological 

 Observatory there, and also to seek a suitable place for the great 

 Reflector." 



Orbit of y Virginis. — The elements of this binary star, an object 

 as important and interesting to northern observers, as a Centauri is 

 to those of the south, have been recently computed by Mr Hind 

 upon the observations solely of Captain W. H. Smyth. The period 

 which they extend over is small, about twenty years, but includes 

 the very critical period of the periastral passage, and Mr Hind was 

 very desirous of ascertaining, by comparison of elements so determined, 

 with those arising from a discussion of the whole of the measures of 

 all other astronomers, what kind of dependence might be placed on 

 the elements of other binary systems, computed under similar cir- 

 cumstances, where, during the interval between the earliest and latest 

 observation, a small portion only of the ellipse has been described, 

 and that depending merely, or altogether on the measures of one ob- 

 server. Though, as he says, these observations in question were 

 taken by one of the most experienced observers of the present day, 

 in this particular department of astronomy, still he had not expected 

 such eminently satisfactory results as have been brought out. The 

 agreement of all the important elements, with those obtained by Sir 

 J. Herschel, from a discussion of all the known observations being 

 so exceedingly close ; as, perihelion passage, according to the first, 

 1836*40 ; according to the last, 1836-39. Position at perihelion, 



