Notice respecting a new CGmet. 59 



ply a lamp for six days, the ordinary time of a man's working, 

 so that they are clieaper than candles. 



If my humble te.->timony can in any degree promote the speedy 

 use of the lamp in other places, it will give me great pleasure. 



I remain, &c. 



To Sir H. Davy. John Pejle. 



XVII. Extract of a_ Letter from Dr. Olbers, F.R.S. of Bre- 

 men, respecting a Neiv Comet ; laith an Account of a IVork 

 of Prifessor Bessfx. Communi-cated hy a Correspond£NT. 



After a long silence I profit by the permission which you 

 once gave me to address you in German, not ijeing able to ex- 

 press myself readily in English, though I read the language with- 

 out diificultv. My present object is to request a favour of you, 

 which may give you some trouble, but which I hope the import- 

 ance of the subject will induce you to grant me : — it is, that you 

 would undertake to collect subscriptions for a work of Professor 

 Bessel, of Konigsberg, of which the prospectus is inclosed. I 

 am wilHng to hope that an undertaking so essential for the ad- 

 vancement of astronomy will be particularly encouraged in En- 

 gland, especially as it is entirely founded on the observations of 

 your incomparable countryman Bradley. According to the pre- 

 sent course of exchange, tl»e price of the book will not exceed 

 about a guinea and a half; and it will be printed as soon as a 

 sufficient number of subscribers shall be found to afford a rea- 

 sonable prospect of the repayment of the expenses. 



I discovered a cornet last year on the 6th of March, and gave 

 immediate notice of the discovery to Dr. Herschel, as weli as in 

 the public papers. This comet was observed in Germany until 

 the '25th of August ; and it is very remarka!)lc for the shortness 

 of the period of its revoluticm. Several of our astronomers, 

 and in particular Mr. Nicolai, now Director of the Observatorv 

 of Manhcim, have calculated its motions in an elli])tical orbit; 

 and the results of their calculations agree extremely well with 

 each other; but none of them has exhibited greater diligence 

 and address in the inquiry than Professor I^essel. These are his 

 elements, determined for the 2(ith April IS 1.5 : 

 Time of the perihelion, 1815 April 25*99SG74,mean time at Paris. 



Longitude of the ascending node 83° 2^' 33'fi3" 



Inclination of the orbit 44° 29' 54 59" 



Distance of the perihelion from the node 65 'ilV 22*29" 

 Logarithm of the shortest distance .... 0-()838lU9 



Eccentricity 0-9312If 68 



Greater semi-axis, or mean distance . i7"r)3383 



Period 74-04913. Motiondirect. 



The 



