S P o 



«ate of the heatens, he maintained, that thefe fpots con- 

 fifted of a kind of matter that admitted of very great and 

 fudden alterations ; that they adhered to the fun, which 

 carried them round an axis of his globe m about a month ; 

 which axis he firft fuppofed to be perpendicular to the plane 

 of the earth's annual orbit, becaufe the courfe of the ipots 

 appeared on the fun's difli as ftraight Imes paraUel to that 

 plane ; which then happened through a particular diredion 

 of the floating motions of the fpots upon the fun's furface, 

 as he foon inferred from the vifible alterations in their Ihapes 

 and fituations to one another, when feveral of them appeared 

 together : and thence he concluded, that the general courfe 

 of the fpots was frequently varied a little, in like manner as, 

 to a perfon viewing the earth from a great diltancc, the 

 clouds would appear to move parallel to one another, and to 

 the equator, with the uniform velocity of the earth's diurnal 

 revolution, unlefs dillurbed a little from that regular courfe 

 by their floating in the atmofphere. At firil he took the 

 apparent motion of the fun's to be, as we have ttated, 

 reftilinear and parallel to the ecliptic ; but in confequence 

 of a fubfequent obfervation of the entire tranlit of a large 

 fpot, and of marking its place at noon, day after day, upon 

 a circular paper anfwering to the fun's dillc, he found its 

 courfe was a little incurvated ; and thence he concluded, 

 that the fun's axis was a little inchned to the plane of the 

 echptic. 



Since Gahleo's time, the fubje£l of the fun's fpots has en- 

 gaged the attention of feveral aftronomical obfervcrs. The 

 pofition of the fun's axis, and the periodical time of his 

 motion round it, have been more exactly determined, the 

 knowledge of which depended upon the obfervation of thefe 

 fpots. In the year 1639, Scheiner publilhed his " Rofa 

 Urfina," containing near 2000 obfervations of folar fpots 

 for 20 years ; in which time he frequently faw above 50 at 

 once: but for 20 years after, betwixt 1650 and 1670, 

 fcai-cely any appeared. He found that many of his fpots 

 fcarcely exceeded 25 days in making an apparent revolution 

 from a given place on the diik to the fame again, that others 

 took up 27 days, and fome others near 28. Scheiner and 

 Caffini the fon have alio obferved, that the periodical times 

 of the nearer fpots to the equator are (horter than thole of 

 the remoter ; and Cafllni the father obferved the like pro- 

 perty in Jupiter's fpots. Thefe irregularities create great 

 difficulties in determining the time of the fun's exaft revolu- 

 tion about his axis. Caffini the father, however, by com- 

 paring many diftant obfervations together, found a common 

 meafure of many fucli intervals of time to be 27^" 12'' 20'" 

 very nearly. Hence it has been concluded, that the pe. 

 riodical time of the fun's revolution to a fixed itar is 

 25"! is^ 15"". 



All fpots confift of a black part in the middle, of fome 

 irregular figure, encompalTed with a nebulous border of a 

 colour lefs dark ; and it often happens, after a gradual de- 

 cay and difappearing of the black part, that its place feems 

 brighter than the reft of the fun, and continues fo for two 

 or three days. Thefe brighter fpots are called facuU ; 

 which fee. 



The fun's fpots are very changeable as to number, form, 

 &c. and are fometimes in a multitude, and fometimes none 

 at all. 



Some imagine they may become fo numerous, as to hide 

 the whole face of the fun, at leall the greateft part of it ; 

 and to this afcribe what Plutarch tells us, -viz. that in the 

 firll year of the reign of Auguftus, the fun's light was fo 

 faint and obfcure, that one might look iteadily at it with 

 the naked eye. 



To wliich Kepler adds, that in 1 547 the fun appeared 



S P o 



reddirti, as when viewed through a tliick mift ; and hence 

 conjetlures, that the fpots in the fun are a kind of dark 

 fmoke, or clouds, floating on the furface of it. 



Others will have them ftars, or planets, tranfiting the 

 body of the fun ; but it i; much more probable they are 

 opaque bodies, in manner of crufts, formed like the fcums 

 on the furface of liquors. 



Dr. Derham, from a variety of particulars which he has 

 recited, relating to the folar fpota, (fee Phil. Tranf. abr. 

 vol. iv. p. 235, &c. ) and their congruity to what we ob- 

 ferve in our own globe, infers, that they are caufed by the 

 eruption of fome new volcano therein, which, at firlt, pour- 

 ing out a prodigious quantity of fmoke, and other opaque 

 matter, caufeth the fpots : and as that fuliginous matter de- 

 cay's and fpends itlelf, and the volcano at lall becomes more 

 torrid and flaming, fo the fpots decay and become umbrat, 

 and at laft faculae ; which faculK he fuppofes to be no 

 other than more flaming lighter parts than any other parts 

 of the fun. 



Dr. Franklin (m his Exper. and Obferv. p. 266.) fug- 

 gefts a conjecture, that the parts of the fun's fulphur, fepa- 

 rated by fire, rife into the atmofphere, and there being 

 freed from the immediate aclion of the fire, they coUeA into 

 cloudy mafles, and growing, by degrees, too heavy to be 

 longer fupported, they dcfcend to the fun, and are burnt 

 over again. Hence, he fays, the fpots appearing on his 

 face, which are obferved to diininifti daily in fize, their con- 

 fuming edges being of particular brightnefs. For other 

 folutions of thefe phenomena, by Wilfon, Lalande, Her- 

 fchel, &c., fee Maculje and Sun. 



The lunar fpots are fixed ; and altronomers reckon about 

 forty-eight of them on the moon's face, to each of which 

 they have given names. The twenty-firft is one of the moft 

 confiderable, and is called Tycho. See Nature, &c. of the 

 Moon. 



Spots, Circular, in Ekaricity. See CIRCULAR. Spots 

 and Colours. 



Spots, Planetary. Allroiiomers find that the planets 

 are not without their fpots. Jupiter, Mars, and Venus, 

 when viewed through a telefcope, (hew feveral very remark- 

 able ones : and it is by the motion of thefe fpots, that we 

 conclude the rotation of the planets round their axes, in the 

 fame manner as that of the fun is deduced fn^m the motion of 

 his maculae. See each planet in its proper place. 



Spots, Lucid, in the Heavens, are httle whitifh fpots, of 

 which there are feveral, that appear magnified, and more 

 luminous when feen through telefcopes ; and yet without 

 any (lars in them. One of thefe is in Andromeda's girdle, 

 and was firll oblerved, A D. 1712, by Simon Marius : it 

 has fome whitilh rays near its middle, is liable to feveral 

 changes, and is fometimes invifible. Another is near the 

 ecliptic, between the head and bow of Sagittarius ; it is 

 fmall, but very luminou-. A third is in the back of the 

 Centaur, which is too far fouth to be feen in Britain. A 

 fourth, of a fmaller fize, is before Antinous's right foot, 

 having a fl;ar in it, which makes it appear more bright. 

 A fifth is in the conltellation of Hercules, between the 

 ftars ^ and >i, which fpot, though fmall, is viiible by the 

 bare eye, if the flcy be clear -nd the moon ablent. 



SPOTSWOOD, in Geography, a fmall town of Middle- 

 fex county. New Jerfey, near tne weft fide of South river, 

 which difcharges itfelf into the Rariton, in a f .uth-eaft di- 

 reftion. It is well fituated for extenfive manufaftories ; 

 9 miles S.E. of Brunfwick. 



SPOTSYLVANIA, a county of the American ftatc 

 of Virginia, bounded north by Stafibrd, and eaft by Caro- 

 line county. It is hilly, and well watered by branches of 

 12 the 



