154 



ASTRONOMICAL PHENOMENA AND PROGRESS. 



distance from the earth. But the error, what- 

 ever it is, is propagated from the solar system 

 into the deepest spaces which the telescope has 

 ever traversed. The sun's distance is the meas- 

 uring rod with which the astronomer metes out 

 the distances of the fixed stars and dimensions 

 of the stellar orbits. An error of three per 

 cent, in the sun's distance entails an error of 

 three per cent, in all these other distances and 

 dimensions. Trifling as three per cent, may 

 seem, the correction runs up to 600,000 millions 

 of miles in the distance of the nearest fixed stars." 



Mr. Hind, also, in the paper already quoted 

 from, remarks of the proposed increase of the 

 solar parallax that by it the earth is brought 

 about 4,000,000 miles nearer the sun, and its 

 annual path shortened by about 25,000,000 

 miles, its orbital motion being correspond- 

 ingly diminished. So, he adds, with the 

 single exception of the moon, both the dis- 

 tances and dimensions of all the other bodies 

 of the solar system, as expressed in miles, 

 must be diminished in proportion. These, 

 however, are matters of curiosity. And he 

 states that as we may suppose, because calcu- 

 lations respecting the heavenly bodies mainly 

 involve relative, and not absolute values, 

 the proposed change in the parallax of the sun 

 will produce but little effect in the most deli- 

 cate astronomical investigations. 



NOTE. Since the above abstract was pre- 

 pared, there has come to our notice a summary 

 of an article contributed by M. Foucault to the 

 " Comptes Rendus," November 24th, 1862, on 

 the "Experimental Determination of the Ve- 

 locity of Light, and a Description of the Ap- 

 paratus." In this, that author speaks of hav- 

 ing found a source of error in the micrometer 

 (an instrument seldom so accurate as is com- 

 monly thought) ; and having obviated this er- 

 ror by means of another method of determin- 

 ing the deviation of the image observed in the 

 revolving mirror, he considered himself at the 

 time of writing able to give with confidence 

 the number appearing to express the velocity 

 of light in space ; namely, 298,000 kilometres= 

 190,249.16 miles, in a second of mean time. This 

 result, if accepted, would imply a less magnitude 

 in the errors of distance, &e., above considered. 



Motion of the Sun in Space. From a consid- 

 eration of the proper motions of the stars in 

 space, Sir "Win. Ilerschel, Argelander, Gallo- 

 way, and others were led to infer that the sun 

 is moving in the direction of the constellation 

 Hercules; and Struve attempted to calculate 

 its annual motion toward that point. From a 

 more extensive series of observations made 

 upon 1,167 stars, Prof. Airy is unable to find a 

 confirmation of this conclusion; and by like 

 observations and calculations Mr. Dunkin ar- 

 rives at the same result. Latterly, it had been 

 proposed to investigate this problem by finding 

 whether or not the direction of motion of 

 comets, before coming into the solar influence, 

 was different from the motion concluded to be- 

 long to the sun. . But Mr. Carrington and 



Prof. Fearnley now declare their opinion that 

 even this method could not be successfully ap- 

 plied ; and they advise that the observation and 

 determination of the proper motions of the 

 stars, with a view to this question, be still per- 

 severed in. 



Some Points relating to the Constitution of 

 the Sun. Sir Wm. Armstrong, in the opening 

 address before the British Association for the 

 advancement of science, at the meeting for 1863 

 (Aug. 26th), made upon this subject, among 

 others, the following remarks : 



" Of all the results which science has pro- 

 duced within the last few years, none have 

 been more unexpected than those by which 

 we are enabled to test the materials of which 

 the sun is made, and prove their identity, in 

 part at least, with those of our planet." The 

 same researches have also corroborated pre- 

 vious conjectures as to the luminous envel- 

 ope of the sun. 



Among the most remarkable discoveries in 

 connection with the sun must be ranked that 

 of Mr. Nasmyth, to the effect that the bright 

 surface of this body presents the appearance 

 of an aggregation of apparently solid forms, 

 shaped like willow leaves, or some well known 

 forms of Diatomacea?, and interlacing one anoth- 

 er in all possible directions. These mysterious 

 objects appear in some way connected with 

 the heat, and [if we can understand what, in a 

 physical sense,, this is] the vivifying power of 

 the sun. They have been seen by other ob- 

 servers, and computed to be each not less than 

 1,000 miles in length by about 100 in breadth. 

 The enormous chasms in the sun's photosphere, 

 to which we apply the diminutive appellation 

 of "spots," exhibit the extremities of these leaf- 

 like bodies pointing inward and fringing the 

 sides of the cavern far down into the abyss. 

 Sometimes they form a rope or bridge across 

 the chasm, and appear to adhere to one anoth- 

 er by lateral attraction. 



A most remarkable phenomenon was seen by 

 independent observers at two different places 

 on the first of September, 1859. A sudden 

 outburst of light far exceeding the bright- 

 ness of the sun's surface, was seen to take 

 place, and then to sweep like a drifting cloud 

 over a portion of the solar face. This was 

 attended with magnetic disturbances of un- 

 usual intensity, and with the exhibition of 

 auroras of extraordinary brilliancy. The in- 

 stant of the effusion of the light was recorded 

 by an abrupt and marked deflection in the self- 

 registering instruments at Kew. Probably, in 

 fact, but a part of the phenomenon was seen, 

 as the magnetic storm attending it commenced 

 before and continued after the event. Perhaps 

 this phenomenon should be regarded as having 

 a connection with the renovation of the sun's 

 heat. Thus, it may be explained on the sup- 

 position of the plunging of cosmical matter in- 

 to the sun with the prodigious velocity whijh 

 gravitation would impart to it, the arrested mo- 

 tion giving place to its equivalent of heat. 



