232 THE BORDERLAND OF SCIENCE. 



But before we pass to the curious questions suggested 

 "by the manifest signs of violent volcanic action on the 

 moon in former ages, when neither water nor air 

 existed in any considerable quantity, let us pause for 

 a moment to discuss the remarkable result attained by 

 G-ussew. 



If we suppose that there really is a bulging out on 

 the earthward side of the moon, to the enormous 

 extent indicated by Ghissew's measurements, we have a 

 singular problem to inquire into. For theoretically, as 

 Newton showed long since, the moon ought to be 

 in shape what geometricians call an ellipsoid. The 

 earth's globe is slightly flattened one way, and we call 

 such a figure a spheroid ; but now suppose that besides 

 being compressed at the poles, she were also (as some 

 think she actually is) compressed (but to a much 

 smaller degree) at two opposite parts of the equator, so 

 that the equator itself was slightly oval. Then she 

 would have her shortest diameter, as now, the polar 

 one; her longest diameter would be the longest dia- 

 meter of her oval equator ; and she might be said to 

 have an intermediate diameter, viz., the shortest dia- 

 meter of her equator. So it should be, says Newton, 

 in the case of the moon. She should be most com- 

 pressed at the poles, or nearly at the north and south 

 points of her disc ; her longest diameter should be the 

 one turned towards the earth ; and a thwart diameter 

 lying nearly east and west would be her third or inter- 

 mediate diameter. Then he calculated the length of 

 these several diameters, and found that the shortest 



