GENEKAL DESCRIPTION OF THE MOON. 113 



opinion that the difference may well amount to as much as 10,000 feet, 

 so that the total relief of the moon may amount to somewhere between 

 30,000 and 40,000 feet. That of the earth from the deepest part of 

 the oceans to the highest mountain summits is probably between 

 55,000 and 60,000 feet; so that notwithstanding- the lack of erosion 

 and sedimentation which in the earth continually tends to diminish 

 the difference between the sea-floor and land areas, the surface of 

 the satellite has a much less range of elevation than the planet. If the 

 forces which have built the mountains and continents of the earth had 

 operated without the erosive action of water, there is little doubt that 

 the difference in height between the highest and lowest parts would 

 now be many times as great as it is on the moon, 



[The following are ten plates selected from the 25 plates in the full 

 memoir.] 



SM 1903 8 



