NATURAL PHILOSOPHY. 139 



these appearances. Some attributed them to the mountains of the 

 moon ; but this hypothesis would not bear a moment's examination. 

 Others \vislu-d to discover in them certain effects of diffraction, or of 

 refraction. But the touch-stone of all theories is calculation; and 

 uncertainty the most indefinite must follow, in reference to their appli- 

 cation to the remarkable phenomena specified, those, namely, of which 

 we have just been speaking. Explanations, giving neither an exact 

 account of the height, the form, the color, nor the fixity of a phenom- 

 enon, ought to have no place in science. Let us come to the idea, much 

 extolled for a short time, that the protuberances were solar mountains, 

 whose summits extend beyond the photosphere covered by the moon 

 at the moment of observation. Following the most moderate compu- 

 tations, the elevation above the solar disc of one of these summits, 

 would have been 19,000 leagues. I am Avell aware that no argument 

 because based on the vastness of this height, should lead to the rejec- 

 tion of the hypothesis, but it ma}' be much shaken by remarking that 

 these pretended mountains exhibit considerable portions beyond the 

 perpendicular, which, consequently in virtue of the solar attraction 

 must have fallen down. 



Let us now take a rapid glance at the hypothesis, according 

 to which the protuberances would be assimilated to solar clouds float- 

 ing in a gaseous atmosphere. Here we find no principle of natural 

 philosophy to prevent our admitting the existence of cloudy masses 

 from 70,000 to 90,000 miles in length, with their outlines serrated, and 

 assuming the most distorted forms, only in further pursuing this hypoth- 

 esis, one could not fail to be astonished that no solar cloud had ever 

 been seen entirely separate from the circumference of the moon. It 

 is towards this determination, the subject otherwise eluding us, that the 

 researches of astronomers should be directed. A mountain being 

 incapable of sustaining itself without a base, the fortuitous observation 

 of a prominence, separated in appearance from the margin of the 

 moon, and, consequently, from the real margin of the solar photosphere, 

 should be sufficient utterly to overthrow, the hypothesis of solar moun- 

 tains. Such an observation has really been made. M. Kutochi who 

 observed the eclipse of July 8th, 1850, writes :--" the slender and 

 redish striated appearance Avhich was found near the northern promi- 

 nence seemed to be completely detached from the margin of the 

 moon." In the eclipse of the 28th of July, 1851, Messrs. Mauvais 

 and Soujon, of Dantzic, and the celebrated foreign astronomers who 

 had repaired to the different parts of Norway and the north of Ger- 

 many, saw in all the selected stations without exception, a spot uni- 

 formly red, and separated from the limb of the moon. These obser- 

 vations put a definite termination to the explanations of the 

 protuberances, founded on the supposition that there existed in the 

 sun, mountains whose summits would reach considerably above the 

 photosphere. When it shall be clearly demonstrated that these lumi- 

 nous phenomena cannot be the effect of the inflexions which the solar 

 rays might experience in passing near the rough parts which fringe 

 the circumference of the moon : when it shall be demonstrated that 

 13 



