ASTRONOMY AND METEOROLOGY. 815 



fuished by extreme eccentricity, while comets of small eccentricity 

 ave been inconspicuous. From this law it follows that brilliant com- 

 ets have long periods ; and he tells us that, with the exception of 

 Halley's comet, which performs its journey in seventy-six years, no 

 other first-class comet has a shorter period than one measured by cen- 

 turies. Mr. Marsh likens the tails of comets to auroral streamers, and 

 considers that their envelopes resemble the electrical discharges in 

 Mr. Gassiot's vacuum tubes, the luminous character being derived 

 from the solid particles which the electrical current transports from 

 the nucleus, just as similar particles are carried off from the elec- 

 trodes in a voltaic discharge. 



PROTUBERANCES ON THE SUN. 



Mr. Balfour Stewart, F. K,. S., in an article in the Philosophical 

 Magazine, suggests that the mysterious red protuberances observed 

 on the sun's limit at the moment of total obscuration bear some anal- 

 ogy to the terrestrial phenomena of the aurora borealis , and he ad- 

 duces several arguments in favor of his supposition. First, he con- 

 tends that the terrestrial aurora is the induced effect in the upper 

 regions of small but rapid changes occurring in the intensity of the 

 earth's magnetism, which itself, according to Gen. Sabine, is influ- 

 enced by the sun. These changes are coincident with auroras, and 

 if in a measure resulting from the sun may occasion similar effects in 

 the atmosphere of that luminary. This idea being communicated to 

 Gen. Sabme, the latter further developed it by remarking that a solar 

 aurora might possibly call forth simultaneous corresponding auroras 

 in all the planets, proportioned to their strength. Mr. B. Stewart 

 concludes his paper with an enumeration of the points of likeness 

 existing between the protuberances, considered as red flames, and ter- 

 restrial auroras. These are : 1. Their extreme height; 2. Their great 

 actinic effect ; 3. Their red or violet color ; 4. Their unpolarized 

 light ; and, 5. The curved appearance of some of the flames, similar 

 in some respects to the auroral arch. 



SOME PECULIAR FEATURES OF THE SUN'S SURFACE. 



At the meeting of the British Association, 1862, Mr. Nasmyth gave 

 a sketch of the character of the sun's surface as at present known. 

 He described the spots as gaps or holes, more or less extensive, in the 

 luminous surface or photosphere of the sun. These exposed the to- 

 tally dark bottom or nucleus of the sun. Over this appears the mist 

 surface, a thin, gauze-like veil spread over it. Then came the 

 penumbral stratum, and, over all, the luminous stratum, which he had 

 had the good fortune to discover was composed of a multitude of very 

 elongated, lenticular-shaped, or, to use a familiar illustration, willow- 

 leaf-shaped masses, crowded over the photosphere, and crossing one 

 another in every possible direction. The author had prepared and 

 exhibited a diagram, pasting such elongated slips of white paper over 

 a sheet of black card, crossing one another in every possible direc- 

 tion in such multitudes as to hide the dark nucleus everywhere, ex- 

 cept at the spots. These elongated, lens-shaped objects he found to 

 be in constant motion relatively to one another. They sometimes 



