THE MOON 379 



superstitions as uncaused motions, self -rotating nebulae, 

 and the like, it is easy to excuse Galileo and his contempo- 

 rary sympathizers for accepting, out of hand, the pre- 

 posterous notion that the so-called craters of the moon 

 are veritably volcanic. But that such an infantile idea 

 has been able to survive the discovery of the mechanical 

 equivalent of heat and command at the present moment 

 the confidence of the great majority of learned scientists, 

 is to me one of the most cryptic of modern mysteries. 



It is not a difficult matter to compute what the 

 moon's temperature should have been at the close of the 

 still-credited Laplacian cosmic process, and the calcula- 

 tion has been made thousands of times. Thus, Doctor 

 Lowell, in his Mars as the Abode of Life (p. 23), says, 

 ' ' On the principle that the heat caused by contraction was 

 as the body's mass, this state of things on the surface of 

 3ur satellite is unaccountable. The moon should have a 

 surface like a frozen sea, and it shows one that surpasses 

 the earth's in shagginess." His calculation, he reports, 

 gives the satellite's temperature as only 27 F. "To 

 point out that any volcanic action could be produced by 

 this quantum of heat", he adds, "is superfluous". All 

 this was long known to astronomers, without, however, 

 in the least influencing their doctrinal teachings. Finally 

 Darwin, with a view to helping matters, came to the 

 rescue with his tidal-evolution theory by which he sought, 

 among other things, to account for the moon's originally 

 high temperature by plucking it bodily from the much 

 more massive, and hence much hotter, earth. 



It then came to be taught that the ruggedness of the 

 lunar surface is due to the happy combination of these 

 two factors, namely, first, the possession by a small body 

 of a cosmic temperature appropriate to one 80 times 

 larger, and, second, a coincident reduction in the weight 

 of substances; the former factor supplying the desired 

 augmentation of the eruptive forces behind the volcanic 

 activities, and the latter accounting for the relatively 

 farther distance to which the lighter-weight debris was 

 driven. It was, in fact, somewhat analogous, in their 



