The Lunar Arctic Region. 49 



THE LUNAR ARCTIC REGION: MARE FRIGORIS : 

 MOUNT TAURUS: POSIDONIUS.— OCCULTATIONS. 



BY THE EEV. T. W. WEBB, A.M., P.E.A.S. 



In our previous description of the neighbourhood of the N.W. 

 lunar limb, we broke off without reaching the Pole. We must 

 therefore now turn our steps in that direction. As a necessary- 

 consequence of the very slight inclination of the lunar axis, the 

 arctic zone, properly speaking — that is to say, the region around 

 the Pole where the sun never rises in winter and never sets in 

 summer — is of much less extent on the Moon than on the Earth ; 

 its radius being only about 1|°, instead of 23 1°. But, as Beer 

 and Madler observe, this would by no means produce a greater 

 equalization of mean temperature than upon the earth. The 

 question, however, of the distribution of lunar climates and their 

 analogy with those of our own globe is a difficult one, being 

 complicated with the absence of any dense atmosphere, which 

 on the earth materially diminishes the force of the oblique 

 solar rays, and, as we have now learned from Mr. Glaisher's 

 balloon ascents, produces meteorological effects not hitherto 

 fully taken into consideration. 



As we approach the Pole we find in the Full Moon a multi- 

 tude of converging luminous streaks, the major part portions of 

 great circles, but some of irregular curvature. Their point of 

 union is the ring-mountain Anaxagoras (No. 46, in the next 

 quadrant) .* These streaks, as B. and M. observe, pass over 

 every inequality of ground alike, and are not at all elevated 

 above the adjacent soil. This they satisfied themselves of as 

 fully in this district as elsewhere, by watching their aspect on 

 the terminator, where a bank of less than 150 feet high must 

 have come out in its true relief. 



Strabo and Tholes, two craters of moderate size, will be 

 found close to each other ; the latter, which is the more east- 

 ernly, being the more regular, steep, and brilliant of the two* 

 Strabo lies about its own breadth distant from Endymion to- 

 wards the Pole. Some short streaks issue from Thales, one 

 running eastward having a very defined edge, like the shore 

 of a sea, on its N. side. When a favourable state of libration 

 brings these objects away from the limb, their aspect is a 

 striking one ; the effect of local shading causing Thales to stand 

 out as a commanding height, in cold and barren insulation. 



N.W. of Thales, and considerably nearer to the limb, lies 

 a crater undescribed and unnamed by B. and M., and not 



* See Index Map of the Moon, vol. v., p. 190. 

 YOL. VII. — NO. I. E 



