338 J. D. Dana on the Volcanoes of the Moon. 
are covered thickly with voleanic mountains. Over a large part 
of the northwest quarter, there is only here and there an eleva~ 
tion, and this comparative nudity extends a considerable distance 
southward across the equator. 
The features of the surface may be nites as of aes 
viz :— 
ws The ring-mountains, anieks are broad truncated cones vith 
immense circular craters. (See the following figures from Beer 
and Madler. ) 
2. Conical mountains, seats like ordinary volcanoes. 
~ 8. Linear or irregular ridges. 
4. Large depressed areas, usually wiebos ans ‘Sat not supped 
to contain water. | 
5. Broad pale streaks, of great length. 
6. Narrow lines, supposed to be fissures. 
Out of the 1095 heights measured by Beer and Midler, ‘stg are 
above 20,000 feet in altitude, and tventy-two exceed 15,750 feet. 
‘The broad truncated cones with. large: circular craters, are its 
most common elevations, and are among the loftiest. ‘The pits, 
as we have remarked, are of all dimensions to 150 miles, and of 
various depths to near 25,000 feet. 'The crater Baily is 1492 
statute miles in diameter ; Clavius is 1431 miles; Schickard is 128 
miles. 20 to 60 miles is the more common breadth. The depth 
of Newton is 23,833 English feet; of Casatus 22,822; of Calip- 
pus 22,209; of Tycho 20,181 feet. The height above the sul- 
* We have stated that Galileo (note to page 336) made the altitude of the high- 
er of the moon’s mountains 8800 metres. Hevelius reduced their height to 5200 
metres, Riccioli, as M. Arago states, increased Galileo's estimate, and his’ obser- 
vations, as calculated by M. Keill, gave for the mountain St. Catherine more than 
14,000 metres. Herschel in 1780, (Phil. Trans. 9 1780, p. 507 ; also for 1794, p- 
40,) sgead again the heights, concluding from his observations that the aga 
did not t excced a “mile and a betray The latest investigations have nena” 
the central plain of a crater or the extorioi surface, or by Hots ing the colette ” 
summit when it first becomes illuminated, and calculating therefrom ; the higher 
the peak, the Jonger will be the shadow, and also, the sooner its top w will be tip- 
ped with light. Should it hereafter be esta tablished that the moon ae an i 
sphere, it must be too slight to affect appreciably the altitudes determin with 
regard to the breadth of the tke nly there can be no more doubt, than with respec 
to the diameter of the moon 
are many who receive ith scepticism the a titans ive wae, or even 
deny where they know noting. ‘At is taking @ high ground, to dispute with all 
” 
