480 PHILOSOPHICAL TRANSACTIONS. [aNNO 1795. 



struction of the sun, I have availed myself of the labours of all these astrono- 

 mers, but have been induced to this only by my own actual observation of the 

 solar phenomena; which, besides verifying those particulars that had been al- 

 ready observed, gave me such views of the solar regions as led to the foundation 

 of a very rational system. For, having the advantage of former observations, 

 my latest reviews of the body of the sun were immediately directed to the most 

 essential points; and the work was by this means facilitated, and contracted into 

 a pretty narrow compass. The following is a short extract of my observations on 

 the sun, to which I have joined the consequences I now believe myself entitled to 

 draw from them. When all the reasonings on the several phenomena are put 

 together, and a few additional arguments, taken from analogy, which I shall 

 also add, are properly considered, it will be found that a general conclusion may 

 be made which seems to throw a considerable light on our present subject. 



In the year 1779. there was on the sun a spot large enough to be seen with 

 the naked eye. By a view of it with a 7 -feet reflector, charged with a very high 

 power, it appeared to be divided into 2 parts. The larger of them, on the igth 

 of April, measured l' 8".o6 in diameter; which is equal in length to more than 

 31 thousand miles. Both together must certainly have extended above 50 

 thousand. The idea of its being occasioned by a volcanic explosion, violently 

 driving away a fiery fluid, which on its return would gradually fill up the va- 

 cancy, and thus restore the sun in that place to its former splendour, ought to 

 be rejected on many accounts. To mention only one, the great extent of the 

 spot is very unfavourable to that supposition. Indeed a much less violent and 

 less pernicious cause may be assigned, to account for all the appearances of the 

 spot. When we see a dark belt near the equator of the planet Jupiter, we do 

 not recur to earthquakes and volcanos for its origin. An atmosphere, with its 

 natural changes, will explain such belts. Our spot in the sun may be accounted 

 for on the same principles. The earth is surrounded by an atmosphere, com- 

 posed of various elastic fluids. The sun also has its atmosphere, and if some 

 of the fluids which enter into its composition should be of a shining brilliancy, 

 in the manner that will be explained hereafter, while others are merely trans- 

 parent, any temporary cause which may remove the lucid fluid will permit us to 

 see the body of the sun through the transparent ones. If an observer were 

 placed on the moon, he would see the solid body of our earth only in those 

 places where the transparent fluids of our atmosphere would permit him. In 

 ethers, the opaque vapours would reflect the light of the sun, without per- 

 mitting his view to penetrate to the surface of our globe. He would probably 

 also find that our planet had occasionally some shining fluids in its atmosphere; 

 as, not unlikely, some of our northern lights might not escape his notice, if they 

 happened in the unenlightened part of the earth, and were seen by him in his 



