( 444 ) [Dec. T, 



I'ROCEEDINGS OF LEARNED SOCIETIES. 



ROYAL SOCIETY. 



DR. HtKSCHr.L has laid before tli is 

 Socitty, ot which he lias been long 

 an a5ive member, a jiapcr on the Direc. 

 tion rf the S'ln and Solar Syftem. The 

 Jtarned ai'i ronomer ccmceived, more than 

 twenty years ago, that it was highly pro- 

 bable there was a motion ot ihe Sun and 

 fclarfvfttm towards ^ HercuJiR ; and he 

 f'dyst'.e realbns which were in 1783 point- 

 ed out lor incroducing a folar motiun will 

 now be much llrengthened by oiher confi- 

 de' ations. We carnot, for the want of 

 figures, f^.llo^A' Dr. Herl'chel in his rcafon- 

 ing on this lubjeiSf. He coiictivts thit 

 the motion of the S-m and lohir lylttm 

 will iiccount for the apparent m(;lions of 

 the l3iE;tr fixed ftar.s upon much ihe eaficft 

 princiuics. Thus by admitting a moiicn 

 <.t -.hi Sun towards >, Htrcnlis, the annual 

 ninji'nt cf fix fiars, viz., Siniu, Atfturus, 

 Capclia, Lyra, Aldeb'tan, Piocyon, may 

 be reduced to little more ihan a", wherea* 

 the iuni cf them would be 5''.3S37 ; and 

 by another table, founded on a calculation 

 ot the angles, and the leaft quantities of 

 ital u.otioiiof the fame fix liars, ii appears 

 that the annual proper motion ot the liars 

 may be reduced to i".4594, which is 

 o".;655 lets than the fum in the former 

 cale. In another paper on this fuhjeft the 

 Po5ior nuar.s to confider the velocity of 

 the (bhr motion. 



Dr. HtRSCHEL hasprefented to the So- 

 ciety ano.hcr |iaper containing Obfcrva, 

 tions on the fingular Figure of the Planet 

 Satuin. " There is not (^^^s the author) 

 perhaps another objtft in the heavens that 

 picl'ents us with I'uch a vaiiety of extraor- 

 dinary phenomena as the planet Saturn. 

 A magnificent globe, encompafled by a 

 ftupendcus double ring ; attended by 

 feven fatellites ; oimmenttd with equa- 

 torid belts ; comprefled at tlie poles j 

 turning upon i.saxis ; mutually eclipllng 

 its ring and iatflhtes, and eclipfed by 

 them; the molt didant of ihe lings alio 

 Surning '.'pon its axis, and the fame taking 

 placr with the larti eft of the I'ate'.lites , 

 all the parts of th^ fyllcin of Saturn ccca- 

 fionally rtfleiling Ijgnt to each other ; the 

 nn^s and moons illuminating the nights 

 of the Satuniian j the globes ai;d fitellitcs 

 enlightening the dark parts of the rings ; 

 and the planet and rings throwing ha- k 

 the Sun's beams upon the mor'n?, when 

 tl»-v are deprived cf thena at the time of 

 conjunclion." 



Bcfides thefe circumftances, which ap- 

 pear to leave hardly any room for addition, 

 there is yet a fingularity lett, which dilfin- 

 guiflies the figure of Satuin from that cf 

 all the other planets. It is flattened at 

 the poles, but the fpheroid that would arife 

 from this fiatteiiing is mod fied by fomo 

 other caufe, which Dr. H. luppofes to be 

 (he attrition of the ring. It refeitible!* 

 a parallelogram, one fide of which is the 

 equatorial, the other the polar diameter, 

 with the four corners rounded ofF, f.)as to 

 leive both the equatorial and polar re, 

 giuns flat'er tiian they would be in a regu- 

 lar rpheroidical figuie. 



By another oblervation, in which Dr. 

 Herlchel had a pood opportunity ot com- 

 paiiiig Satuin with Jtipiter, he ibund the 

 fiyuie of the two planets to be decidedly 

 different. The flatse'ing at the poles and 

 on the equator of Siturn is much greater 

 than it is on Jupiter, but th' curvature at 

 tlielatiiune of fVom 4.0° to 4.8° on Jupiter 

 is Ids than on Saturn. 



As the refult of another fct of obferva- 

 tions, Dr. H. fuppofes the latitude of the 

 greatelf curvature to be lei's than 45 de- 

 grees. The eye will alfo dittinguifti the 

 difference in the three diameters ot Saturn. 

 That which pafies through the points of 

 the greaieft curvature is the largert, the 

 equatorial the next, and the polar diameter 

 the fmallcif. The following table give* 

 the proportiors : 

 The diameter of the greateft 



curvature, - - - 36 



The equatorial diameter, - 35 

 The polar diameter, - - 32 



Latitude of the lyngeft diameter, 43'. 20' 

 The oblervations thrown out in this pa. 

 per concerning the figure of the body cf 

 Satuin, will lead to fome intricate re- 

 fcarchcs, by which the quantity of matter 

 in the ring, and its folidity, may in fome 

 meafure be afcertaincd. They affovc^ alfq 

 a new jnftance of the efFett of gravitation 

 on the figure of the planets ; for, in the 

 cafe of Saturn, we flidl hive to confider 

 llie oppolite infl.ience of two centripetal 

 and two centrifugal forces ; the rotation of 

 both the rirg and plantt having been 

 afcertained in 10 iie ot Dr, Herlcher* for- 

 mer papers. 



Mr. H.\tchett has given two paper 

 " On an Artificial Suliftance which pof- 

 feffes the principal charafleriftic Properties 

 cf Tanning." He defines tanning to be 

 a peculiar lubftance or principle which is 

 naturally 



