390 Intelligence and Miscellaneous Articles, 



be ascribed to effects of electricity whose precise local causes re- 

 main unknown. The most brilliant auroras have indeed usually hap- 

 pened about the time of the autumnal equinox. I may remark in 

 conclusion, that on the same day and three hours previous to the 

 light in question (Sept. 29), some beautiful rainbows are re- 

 corded; and that during the night, small meteors called falling stars, 

 which left trains of light behind them, are said to have been abun- 

 dant. I am, Gentlemen, yours, &c. 

 Boreham, Essex, Oct. 4, 1828. T. Forstek. 



SOLAR SPOTS. 



Having determined the time of the revolution of the macula: so- 

 lares under our last month's Meteorological Report, and minutely 

 observed and noted for some years past their formation, as well as 

 the mutations which they have undergone, independently of their 

 apparent augmentation in approaching to, and linear contraction in 

 receding from the sun's centre, we shall now make a few concise 

 remarks thereon, and prove the sphericity of the sun by the com- 

 parative time of their apparent motion upon the diametrical divi- 

 sions of his disc. We formerly pointed out the mutability of the 

 nuclei and umbrae, or penumbrae of the large maculae, or black spots; 

 yet they appear to have a fixed position at their bases, and evidently 

 increase in height, divide into several distinct spots in the same um- 

 bra, and the matter of their composition sometimes appears like a 

 dark thick fluid, with a smoky substance proceeding from it, de- 

 taching itself from, and moving in a contrary direction to the course 

 of the spot. On such occasions the umbra gradually disappears, 

 as if to make way in the part where the separating matter moves 

 from the original mass. Hence it would appear, that the matter of 

 such spots is by some powerful agency liquefied ; but whether from 

 the effects of heat communicated to the body of the sun, in the same 

 way as heat is produced by the union of the solar rays with the dense 

 medium of our atmosphere and communicated to the earth, it would 

 be impossible to determine. If we could be assured by any philo- 

 sophical experiments of the probability of a superior calorific quality 

 of the solar rays in the atmosphere of the sun to that which they possess 

 in the earth's, we might be allowed to contemplate greater effects of 

 heat at and below the sun's surface, than have ever been observed on 

 the earth's, and also the probability of frequent eruptions from vol- 

 canic matter produced by such heat, similar to those of Etna, Vesu- 

 vius, &c. Indeed, the sudden appearance of the macula 1 , their rising 

 conically from their bases, and their liquid and smoky aspect on some 

 occasions, seem to favour such an idea ; but thermometrical experi- 

 ments, and the perpetual snow on the tops of some of the highest 

 mountains, prove the solar rays to possess but a feeble calorific 

 quality in such high situations, in comparison of those that impinge 

 on the plane of the earth's surface, and militate against the suppo- 

 sition, which was strongly entertained by the first observers of the 

 solar spots. Modern observers have signified that the nuclei of the 

 maculae are opaque mountains on the sun's surface, some of them 



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