288 On the Large Achromatic at Paris. 



object glass actually in use is in proportion to Mr. Struve's (if all 

 of it be effective) as 70 to 92 nearly ; a difference not very 

 hard to be allowed for. I have seen the nebula in Orion ; the 

 planets Jupiter and Saturn with the Paris telescope ; and with 

 their appearances in Mr. Herschel's 20 feet reflector I am perfectly 

 familiar, and the comparison is many times in favour of the latter. 

 The power of the 20 feet reflector at Slough is well authenti- 

 cated ; and if the indefatigable astronomer of Dorpat will turn his 

 probably matchless achromatic upon some of the faint nebulae in 

 the constellation Virgo, or upon some others not easily resolvable 

 into stars, he will soon satisfy himself, that his ideas of its space- 

 penetrating power are much overrated. 



James South. 



P. S. — The star f Bootis was seen " close double" by Mr. Pond at 

 Lisbon, perhaps 20 years ago, and, as I believe, with a Newtonian 

 reflector of 6 inches aperture ; and the circumstances mentioned 

 in a letter written by him to Dr. Wollaston. The instrument 

 with which I first observed it, in 1810, " close double," was a re- 

 flector of the worst possible construction, viz., a Gregorian re- 

 flector of 6 inches aperture and 30 inches focal length, but a very 

 perfect instrument made for me by Mr. Watson in the year 1809, 

 and which is now in the possession of my friend, Mr. Frederick 

 Perkins. 



I am happy to say that I have observed Encke's comet, and 

 also the comet of the constellation Taurus four successive nights, 

 viz., August 21, 22, 23 and 24. 



Art. VIII. Observations on Mr. Fraunhofer's Memoir on 

 the inferiority of Reflecting Telescopes when compared 

 with Refractors. 



Extract of a Letter from J. F. W. Herschel, Esq., F.R.S., 

 to M. Schumacher. 

 Dear Sir, Slough, 1825, Aug. 15. 



In the 74th Number of your Astronomische Nachrichten, you 

 have obliged the astronomical world with Mr. Fraunhofer's account 



