PICKERING. 
LUNAR AND HAWAIIAN PHYSICAL FEATURES COMPARED. 
175 
and southeastern flanks of Copernicus, within one diameter of the crater rim. A 
much larger and more conspicuous crater rill occurs one and a half diameters to the 
northwest of Copernicus. The craterlets in this case are so distinct, however that 
the rill-like character is not so well marked. 
Another type of depression that is found upon the Moon is known as a river-bed 
from its resemblance to its terrestrial analogue. Thirty-four of them 
have been catalogued. They have been so fully described else- 
where, Annals of the Harvard College Observatory, XXX II, 84, that 
it is unnecessary to more than refer to them here. The figure 
represents one of the larger ones. It is found on the slopes of Mt 
Hadley. Its length in a straight line is 50 miles, and its maximum 
breadth 2000 feet. It tapers uniformly from one end to the other. 
In Figure 6 a marking is found closely resembling one of these river- 
beds. It is situated due south of Kies and west of Mercator. Its 
true character can only be ascertained by visual observations made under excep- 
tionally favorable atmospheric conditions. 
gument of those who deny that water ever existed upon the 
that if such were the case, signs of erosion would be found 
A fav 
Moon is the statement 
upon its surface 
these signs are 
In the case of the Earth, where vast bodies of water are prese 
very pronounced in the eroded valleys of mountain regions, and the 
alluvial plains of the more open country 
the Moon no such signs are to be found 
Wh 
ch 
detail upon 
This makes it certain that large q 
of water could 
expect such to be the 
have been found upon its surface, nor indeed should we 
considering the small 
of the force of gravitation 
existing there. If the Moon ever possessed any water at all, it must have been in 
comparatively small quantities, and we should accordingly look among its finer detail 
for any evidence of its former 
Fig 
34 
presents Theophilus, a crater some 64 miles in diamete 
The 
tral peaks rise 5000 to 6000 feet abo 
numerous 
deep valleys, four being clearly shown in the photograph 
the crater floor, and are indented by 
It is believed 
that these valleys are due to erosion, and are analogous to those shown in Figure 36. 
presents a mountain ridge just back of Honolulu, and was taken from 
Similar valleys occur on the central peak of Eratos- 
of Copernicus they have cut so deeply that they have actually 
This fig 
another ridge called Tantalus 
thenes 
In 
divided the 
have come 
central mass into three distinct 
from a general atmospheric cir 
The precipi 
but more likely from steam 
