450 Astronomical Societjj: Sir J. Herschel's Observations 



II. Extract of a letter from Sir John Herschel to F'rancis Bally, 

 Esq., dated Cape of Good Hope, October 22, 1834 : 



** The climate proves much more favourable for astronomical ob- 

 servation than, during the summer and autumn, I had found reason 

 to expect. Since thesettingin oftheN.W.v^inds (in July, August,Sep- 

 tember, and October, the season being at least a month later this year 

 than usual), the nights have been frequently superbly clear and tran- 

 quil, and the definition of stars far beyond anything I ever witnessed 

 at home, allowing the habitual and agreeable use of magnifying 

 powers such as could only be used in the rarest nights in England, 

 and then with difficulty. A brief recapitulation of a few of the more 

 interesting objects and remarks which have fallen under my notice 

 may not be unpleasing to you. 



*' We landed on the 16th of January; and on the 22nd of February, 

 the 20-feet telescope being erected and the mirrors unpacked, I turned 

 it, for the first time, on the southern circumpolar heavens. The no- 

 velty and variety of the objects then seen induced me to defer the 

 commencement of regular sweeping till some of the principal among 

 them had been examined, — such as the wonderful nebula about ri Ar- 

 gus — the Magellanian clouds — the great cluster adjoining the Nubi^ 

 cula minor, and that superb one w Centauri, &c. — and till habit had 

 familiarized me with the delusive appearances assumed by objects 

 under the influence of the S.E. winds, &c. 



" On the 5th of March my sweeps commenced, and have conti- 

 nued, at the average rate of about 10 sweeps per month (cloudy and 

 moonlight nights being, of course, nodes non), in the course of which 

 1 have already accumulated a pretty extensive collection both of ne- 

 bulae and double stars ; though, in close double stars above the 10th 

 magnitude, this hemisphere is decidedly poorer than the northern. 



" On the Istof April 1 discovered, in R.A. 9^ 17"S N.P.D. 147°35', 

 a beautiful planetary nebula having a perfectly sharp well-defined 

 disc 3" or 4" in diameter, and of a uniform light. Its appearance is 

 precisely that of a small planet, with a satellite about 1^ diameter 

 from its edge. Mr. Maclear has been obliging enough to determine 

 its place with great exactness by the circle, by several observations, 

 from which it appears to have no planetary motion. 



" On the 3rd of April I discovered another fine planetary nebula, 

 having a perfectly sharp disc, without the least haziness, of about 6" 

 diameter. The most remarkable feature about this is its evident blue 

 colour, which needs not the presence of lamp light, or that of any red 

 star, to be very conspicuous, as it appears when the nebula stands 

 alone in a dark field. This also has since been (at my request) ob- 

 served with the circle at the Royal Observatory. 



** On the 26th of June I observed an extremely remarkable 

 object, of the class of close double stars, centrally involved in a ne- 

 bulous atmosphere. Its place is in R.A. IS'M/^'SO^i, N.P.D. 

 129° 9'+. The diameter of the nebula is about 2', and the stars 

 are equal, each of them 9*10 mag., distance about ]-^" or 2". The 

 nebula is nearly uniform, or, at least, very little condensed about the 

 star. 



