Solar Observation. 391 



"which we are indebted to Secchi, relates to a singular convo- 

 lution of nebulous streaks, RA. 17k 55rn. 18s. DS. 24° 21' 15". 

 This is M 8*, or Gen. Oat. 4361. He says (1865, Aug. 8) that 

 this object " se trouve notablement changee. La portion qui 

 divisait ses ovales a disparu, et les ovales ne sont qu'un canal 

 presque continu." The ovals are three included spaces, one 

 entirely, two others comparatively dark, which were, when 

 figured by H. at the Cape (1837, June 27), divided by two 

 streaks of irresolvable haze. There is, indeed, some difficulty 

 in reconciling HVs description and drawing (semi-inverted, it 

 must be remembered, owing to his front view) with the ex- 

 pressions of Secchi. If I interpret the former aright, his 

 three ovals thrown into one would not form a continuous canal, 

 but an opening bent back at an acute angle, and Secchi seems 

 to be referring to another opening described by H. as a larger 

 and more ill-defined basin distinct from the ovals, and lying in 

 the same straight line with two of them. But whether this con- 

 jecture may or may not be right, there seems strong evidence 

 of change. H. observes that the nucleus (which is in the p 

 streak) is not stellar, and greatly resembles that of the nebula 

 in Andromeda. Secchi finds that under the spectroscope it 

 exhibits " la raie ordinaire," the usual bright band of gaseous 

 matter. To a suspicion that the great aperture of H/s 

 reflector (184; inches, front view) might reveal interruptions of 

 continuity which Secchi might not perceive, it might be replied 

 that the former was on the other hand unsuccessful in tracing 

 any connection between the principal mass of the Orion nebula 

 and that surrounding the star c. 8 M is not included in the 

 Bedford Catalogue ; it has now left our evening sky, but may 

 form an interesting object of search in another year, when 

 Sagittarius is in a suitable position. f 



SOLAE OBSERVATION". 



The " Solar Caps " or dark glasses which have hitherto been 

 adapted to the eye-pieces of telescopes to intercept the heat, 

 and as much as is unnecessary of the light of the sun, are all 

 more or less objectionable as giving a tint to the solar image 

 which might interfere with the real colour, and in some cases 

 perhaps affect the visibility of the more delicate details. A 

 very ingenious contrivance has lately been introduced by G. 

 and S. Merz of Munich to obviate this defect. It is well 



* Ml in the Astronomische N~ac7iricMen, from a misreading of the Cape 

 Observations. 



f It should have been noticed before that subsequent investigation has shown 

 the relative fixity of the nebulous star 45 1$. iv. and its companion : so that the 

 suspicion of proper motion advanced in Int. Obs. vii. 188, and derived from 

 earlier measures, must be abandoned. 



