48 Do Rivers occur in the Moon ? 



so much keenness to conjectures, might have saved us from many 

 useless hypotheses, which are any thing but creditable to 

 science, if they had attempted to base their ingenious conjec- 

 tures upon the evident data of theory and observation, rather 

 than on sheer possibilities. It is hoped that our powerful 

 glasses will enable us to dispel the obscurities which surround 

 the moon. But instead of this these individuals only deepen 

 the obscurity ; and never will it be removed so long as the reins 

 are in this way given to mere conjecture. Accurate observa- 

 tions alone, freed from all preconceived opinions, and repeated 

 with indefatigable perseverance, are the sole means in our power 

 by which progress can be made. 



S. Do Rivers occur in the Moon f — The question of the ex- 

 istence of a system of drainage by means of rivers in the moon, 

 is intimately connected with the other which refers to the na- 

 ture of the large grey markings which it presents. If these 

 latter be not really seas, it is quite useless for us to search 

 on the moon"'s surface for rivers analogous to those we find on the 

 Earth. Now, it is to be observed that in all the regions to which 

 the appellation of seas has been given, besides the annular moun- 

 tains, and the clear and brilliant- peaks which have sometimes 

 been taken for islands, there are likewise many flat and broad 

 crests, which extend themselves in all directions, and which, as 

 to colour, in no respect differ from the lower districts, as should 

 happen were these flat elevations land, and the others water. 

 Towards the epoch of the moon's quadratures, a great number 

 of those surfaces which are among the most brilliant at full 

 moon, assume a darker shade, which is altogether analogous to 

 that of the sea, although there can be no dispute that they par- 

 take of the nature of continents. Nay, there are even moun- 

 tainous regions, such as that of the neighbourhood of the 

 spot Schroder, which appear at the full moon darker even 

 than the seas themselves, although it is evident, at the first 

 glance, when they exhibit themselves near the margin of the 

 luminous portion, that it is quite impossible they could be 

 covered with water. It follows, that we cannot conclude from 

 the dark colour of any region, that it is liquid. 



4. Lunar Atmosphere. — These considerations have an inti- 

 mate connection with the question of the existence of a lunar 



