vMch appeared during the I^ar 1816. 185 



otherwise they would not deviate far from the line pursued by 

 the revolution of its axis. This indeed has long been ascertained 

 to be the case ; for though the general course in which the spots 

 move, usually corresponds with the line of the sun's equator, 

 they have sometimes been seen to pass in various directions 

 within the equatorial region. Speaking of these maculae, Adams 

 says, " the paths they descrilje in their course over the disk are 

 extremely different, sometimes being in straight lines, sometimes 

 in curves ; at one time descending from the northern to the 

 southern part of tlie disk, at other times ascending from the 

 southern to the northern part*." It must be observed, however, 

 that these irregularities are of rare occurrence — that the spots 

 very seldom pass what may be called the tropics of the sun, and 

 that they have n^ver been seen near the poles. 



Few, if any, of the spots which appeared during the last year, 

 are to be considered of large size ; nor were there many sur- 

 rounded wirh an umbra, which is usually the case with those of 

 large dimensions. 'I'he two above described, which were seen 

 in beptember, though larger than any others, were by no means 

 to be esteemed as occupying any material portion Of the disk ; 

 and although numerous small spots, sometimes scattered with- 

 out order, and sometimes collected in clusters, were almost al- 

 ways visible; yet the quantity of light intercepted by them 

 must have been perfectly insignificant compared with the whole 

 areaf. The spots also remained in general but a short time, 

 scarcely ever could they be traced through two successive revo- 

 lutions; and indeed none have ever been known to continue 

 long. As an instance of the rapidity with which thev sometimes 

 change, a circumstance observed in October last will fully ex- 

 emplify. On the Sth of that month, there were fourteen spots 

 of various sizes upon the sun's disk ; most of them faint and 

 small, as figured and coloured black, in No. 4 ; the whole 

 placed to the north of the equator: but on the 1 1th, the black 

 spots were all entirely vanished, and three others were seen on 

 the south of the equator, in the situation in which the spots are 

 marked in outline. The intermediate days proved so cloudy, 

 that no observation was made, whether this change had been 

 produced suddeidy or gradually. 



With the exception of these appearances, nothing of the least 

 importance occurred to the writer's notice during the last six 

 months of the year lalfi, with respect to the solar niaculce. 

 The disk of the sun is scarcely ever free from spots, but they are 

 generally small and of short continuance, of course they present 

 nothing worthy of particular observation. 



• Lt.-cturcs, vol. iv. p. 220. 



t .Some have statrii that the Ir.r^e spots contiiiiiiiig nuclei, are often con- 

 verter! into hnjihtcr spots, which they terijip(l^rtf?</i. The writer of tliis 

 ha-i never been so fuitunate as to see this {ihienomenon occur. 



