346 FROM NEBULA TO NEBULA 



it is 83 miles long by from three and one-half to six miles in 

 width, and from its positioning bespeaks kinship to the Imbrian 

 deluge, thus uniting the furrow group of the western district 

 with the eastern sculpture system. 



BRIGHT RAYS. The system of brilliant rays which radiate 

 from the crater Tycho down the lunar disk, like luminous par- 

 allels of longitude, and also the wavy streaks converging upon 

 Copernicus; the lesser systems of Proclus, Kepler and Snellius, 

 are the most enigmatic phenomena of the moon's surface. Those 

 emanating from Tycho extend for vast distances across the lunar 

 disk; in one instance that of the one crossing the Mare Ser- 

 enitatis near 18,000 miles. Straight as the famed canals of the 

 desert planet Mars, they seem not to mind obstructing craters or 

 elevations in their predetermined path. As a contrast, those ra- 

 diating from Copernicus are branched and wavy and much shorter 

 than the Tychonic phenomenon. * * * 



Most conspicuous at full moon, under the vertical solar il- 

 lumination, they seem to be superficial colour-streaks only, and 

 one can be seen on the inner floor of Saussure, near Tycho, and 

 may even be traced up its inner cliffs, like a vein of volcanic trap 

 piercing sedimentary rock-strata on our own planet. This is a 

 treacherous analogy, however, as Mr. R. S. Tozer has pointed 

 out. "The lowest visible stratum on the moon is dark, the con- 

 figuration of the edges of the light coloured portion showing 

 plainly that the darker portions extend underneath. * * * Whence, 

 then, the light coloured lava ? 



These brilliant rays cannot be inner material extruded from 

 beneath a crust rent by tidal stresses, since an exact restoration 

 of level which would not cast shadows at sunrise or sunset along 

 hundreds of miles would be practically impossible. But the sug- 

 gestion advanced by Mr. William Wurdemann of Washington, 

 D. C, seems more plausible; viz., that "a meteorite, striking the 

 moon with great force, spattered some whitish material in va- 

 rious directions." Furthermore, Professor Gilbert, in the lecture 

 previously adverted to, made the prophetic suggestion that "per- 

 haps the free iron and nickel of meteorites may stand sponsor 

 for free sulphur or phosphorus in moonlets." 



When astronomers undertake to theorize, there ap- 

 pears to be no limit to the violence of the assumptions 

 they permit themselves. Because one planet out of eight, 

 Saturn, has a ring, it is taken for granted that the earth 

 had one, and a fantastic hypothesis is straightway built 

 upon the gratuitous idea. No one seems to ask, or care, 

 whether the size of the planet can have any bearing on 

 the matter, or whether the distance and measurements 



