ITijhry of AjlroiiAinv for ihe Ytar 1799. 3I 



hibit the ^lobc of the earth, a pair of conipafl'c^ c.xtenJcd from 

 the Equator to the Pole, the conitcllatioii of the LeH'cr licar, 

 and the followins^ uifcrlption — "Ualtv of meafurcs, ten niil- 

 lionth-part of a quarter of the mcriilian." The diameter ot' 

 i.ht> medal will be two inches, and will be executed by C- 

 JoiiflVoy. k was propol'ed in a report prcfente'd to the Iii- 

 ftitute on the 20!h of October, by C.David, Moittc, Leblond 

 -Mongez, Laplace, Delambre, Leveque and Gofl'elin, and was 

 adopted by a law of December 10. 



Bv reducing thefc meafurcs to the temperature of ten de- 

 grees, which is the mean degree of the iieat at Paris, and 

 that in the caverns below the obfervatorv, I find the 45tU 

 degree to be 57012 toifes, inflcad of 57031 which I had 

 adopted in my allrononiy. This is 19 toifes lefs ; the mean 

 radius of the earth 3268159 toifes, lefs bv 1323 toifes than 

 my table, uliich hitherto has ferved as a rule in books of 

 natural philofophy. This, without doubt, is very little in 

 regard to the extent of the earth : we are therefore pretty 

 well acquainted with its fize, but \vc arc not fufficiently ac- 

 (juainted with its irregularities; and this, at any rate, is one 

 •important refult from this new labour. 



This vear has furnilhed three new comets. On the i5lk 

 of December 1798, C. Bouvard difcovered, at the obferva- 

 torv, a fmall one in the conllellation of Hercules; it was 

 fecu only during fix days, and difappearcd on the nth of 

 December in Aquarius, but C,. Burckhardt calculated its 

 orbit with all the prccifion poffiblc*. 



C. Mechain, to whom we are already indebted for the 

 difcovery of fo many comets, found one on the morning of 

 the 7thof Auguft, which is the 90th according to the general 

 catalogue in the third edition of my Altronomy. It was very 

 fmall and without any tail, but cxcecJinglv clear; it was 

 above the Lynx, in the conftcUation which Hell formed in 

 1790, under the name of the Grand Telefcope of H<rrfehel. 

 At thrcp o'clock in the morning it had 107° 47' of right 

 afccnfion, and 43* 54' of north declination. It was among 

 the ftars which C Lefran^ais obferved on the yth of March 

 1794, fo tiiat very cxa£l politions were inunediatt ly obtained. 



' Ccinnsjiirancc dcs Tcms. an. 10. p. jSp. 



C. Mechain 



