New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1904-12-18
CRACKS IN THE Mooy's CRUST.

The lunar marking reported by Mr.. Perrine of
the Lick Observatory, a few days ago belongs
to class which has recently attracted q good
deal Of notice. but which appears to have been
misunderstood when first observed. Unlike the
broad white streaks radiating from central
points and giving the moon the appearance of
peeled orange, the cracks are black and mar
row. Again, the streakS are apparently stains
or sheets Of matter everything the surface, where
as the cracks are grooves or crevices some OF
them a mile deep. Thinking that they might
have been caused by the erosiye action Of
streams Of water, astronomers have called the
cracks "rills' and valleys" applying the for
mer term TO the narrower ones and the latter
10 the broader. These names must now be con-
sidered unfortunate, for the supposition on
which they are based is not now accepted by all
experts. They convey what is probably an err
roneous idea to the uninitiated, just as the word
canals" does when used to designate certain
gray lines on the planet Mars.
The total absence of water on the moon at the
present time does not prove anything regarding
the distant past. However, there are other rea-
sons for skephciSm concerning the erosion
theory. Professor \. S. Shaler. of Harvard Uni
Versity, high authority in geology points out
a radical difference between the sides of the
lunar cracks and those of water worn burrows
on the earths surface. The former are steep
while the latter usually slope gently. Moreover
it Is sometimes possible to see at the bottom OF
a lunar valley pits, or craterlets, of the kind
which appear in great abundance all over the
moon and which are indications Of volcanic
action. One would think that water would have
ground such Irregularities smooth, so as TO be
unrecogniZable. Professor Shaler is convinced
accordingly. that the cracks We're formed nv
1.-THE drawing apart Of their walls" in other
words, by shrinkage of the lunar crust In
that opinion the majority of astronomers will
doubtless concur, especially after reading his
discussion Of the matter in the latest report Of
the Smithsonian Institution.
The next questions which will arise IN napy
minds are: What caused the shrinkage referred
to, and why did it affect the moon in the man
ner described? 1t was once CUSTOMARY n az
count for the formation of great mountain
chains in the following manner: II wac s,,n
posed that the terrestrial mass, ages ago was
much hotter than it is now, and PERTAINS was In
a molten state The outermost norton 1ro. no
ieved to have cooled first and 10 have hecop,e
more or less rigid in consequence Suhsacuan+
~, It was assumed, the Interior lost some Of IFS
original neat ana underwent dlminution Of
volume Thereupon the shell became wr,nlIad
not being able 10 shrink any more Now 70
events actually occurred in that order IN +ba
globe it would be natural to exnecf tbe same
sequence on the moon. ApparentIv however
the rule was reversed. There was evidently
period Of lunar history when the crust was too
small and too tight not too big and too loose
TO TT its contents. How, then, shall the dis.
crepancy be explained?
For reply one is left largely to conjecture
but reconciliation between the two hypothesis
is not Impossible If. for instance, the moon
lost its CLOAK or air and water vapor sooner than
the parent body. radiation would take place
more rapidly from the former than from the lat
ter, and an essential difference In the rate
might cause perceptibe difference I'm effects
Both bodies would, Of course be subject 10 the
same laws but If the conditions were dissimilar
the results might be so. likewise Again. geol.
ogists are today less unanimous than former