1869.] Astronomy. 419 



amonnt would be difficult to deal with, and would cast a certain 

 amount of doubt over the whole of the instrumental corrections. 

 By comparing together the observations made at Greenwich by 

 Messrs. Dunkin, Ellis, Creswick, and J. Carpenter, JMr. Stone has 

 discovered that a real personahty exists, but it is so small, that, as 

 far as Grreenwich observations are concerned, the uncertainties 

 introduced into coUimation-determinations may be neglected as 

 insignificant. 



Mr. Browning describes a remarkable train of sun-spots, visible 

 on the 7th of March. He attempted to observe them with the full 

 aperture of his fine 12-inch silvered-glass reflector, but the defini- 

 tion was so bad, owing to the state of the atmosphere, that he had 

 to reduce the aperture to 6 inches. He then introduced what is 

 called a solar plane, that is, a plate of parallel glass silvered on the 

 exposed side, into the mouth of the telescope. Tlie spots thus ob- 

 served presented the appearance of an almost continuous penumbra, 

 in an irregular hollow curved hne, with umbrae at intervals ; 

 some of the umbrae containing blacker nuclei. On the convex side 

 a portion of the penumbras assumed the form of a pair of compasses. 

 He found the outside dimensions of the cluster to be from E. to W. 

 97,700 miles, and from N. to S. 27,130 miles. The group was 

 the largest which had appeared during the recent outbreak. The 

 dii-ection of its length was almost exactly parallel to the sun's 

 equator. A remarkable circumstance attended the approach of the 

 spots to the edge of the sun's disc ; the faculous matter around 

 the spots became gradually brighter and brighter, until, when the 

 spots had reached the limb, it quite obhterated the penumbra. 

 The black spots were then seen surrounded by a white border ; a 

 distinct proof, if any were needed, that the faculae are above the 

 solar surface. 



Mr. Browning also describes an unproved method of mounting 

 finders. Every observer is aware of the inconveniences which 

 result fi'om the imperfect plans at present used for adjusting 

 finders. Mr. Browning proposes a remarkably promising plan, so 

 simple in its details, that the wonder is it has never been used 

 before. In place of the two rings, each with three adjustment- 

 screws, the only arrangement hitherto applied to a movable finder, 

 Mr. Browning has the finder attached to two uprights. Its attach- 

 ment to the one nearest the eye-piece is so arranged that the 

 finder can be shifted round a horizontal axis perpendicular to 

 the axis of the telescope ; the attachment to the other permits of 

 motion round a vertical axis (the telescope being understood, for 

 the purposes of this description, to be placed in a horizontal posi- 

 tion). It is the more necessary that a simple mode of adjusting 

 finders should be made use of, because in spectroscopic observations 

 the star or other object under examination must be brought exactly 



