FliOCEFDIXGS OF THE POLYTECHNIC ASSOCIATIOX. 821 



reckoned by tliousands, and their aggregate area would cover over 

 one-fifth of the whole surface, not including those which are more or 

 less obliterated by time and modern eruptions, and the remains of 

 which may be traced almost anywhere upon the surface, showing a 

 total dissimilarity in the two cases, as no globe could contain a 

 sufficient quantity of interior fires to have produced such an extended 

 rasult and be identical with our volcanoes and the forces which pro- 

 duced them, 



Tycho presents itself as a [fair exponent of the ring mountain 

 formation, and the ray system which radiates from it in every direc- 

 tion proves it to have been a single vent, though it is fifty-six miles 

 in diameter, and there are others which are three times greater than 

 this, while single volcanic vents are comparatively mere points, 

 besides a volcanic crater is but a depression in the top of the mountain 

 which it forms, while the lunar basins have their floors depressed 

 three times as far below the apex of their mountain ramparts as that 

 apex rises above the general level of the moon's surface upon the 

 outside ; showing conclusively, that they have no characteristics in 

 common with terrestrial volcanoes, andjif it be a truth that like 

 causes produce like effects then they are not volcanoes in any sense 

 of that word. 



Ancient Ray Systems and Basins. 



A further evidence of the fluid nature of the agent employed will 

 be found in the ray systems which proceed]]from the basins of Coper- 

 nicus, Kepler and Aristarchus, Those three are amongst the more 

 ancient formations, and the dark shade from the lowlands in which 

 they are situated has'spread itself over all their features, hiding and 

 obscuring nearly every characteristic but the streaks and the basins 

 themselves ; but this has tlie effect of revealing the ray system with 

 greater distinctness and, consequently, enabling us to trace it with 

 more accuracy. 



The basin Copernicus is about four times longer than either of the 

 other two, tliough all three are evidently of the same epoch. The 

 rays from Copernicus, which proceed toward Kepler, show by the 

 results that the active causes which produced them have overpowered 

 the force which was evolved from Kepler in the opposite direction, 

 pushing back the flow toward the latter basin, compelling it to make 

 a circuit around its source, though at some distance from it, as if the 

 energy of the lesser volume, naturally gathering strength as it was 

 driven back upon the point from whence its power was derived, 



