518 Notices of Books. [October, 



abundant agility above indicated." It only remains to be men- 

 tioned that no object which could possibly be erected by an 

 intelligent being has ever been observed on the moon's surface, 

 even by the use of our most powerful telescopes. Neither, 

 during the two centuries and a half in which the moon has been 

 carefully scrutinised, has any evidence of physical change ap- 

 peared ; all evidence seems, indeed, to show that the moon is 

 " a dead and useless waste of extinct volcanoes." 



Varieties of colour are noticeable on the moon's surface ; some 

 regions appear white, and would be spoken of as snow-covered 

 if it were not impossible from the fact that water and air do not 

 exist in the moon. Then there are grey, and greenish, and pale 

 red regions. 



An interesting account will be found (pp. 272 — 282) of the 

 experiments which have been made in order to determine the 

 heat of the moon, — notably the recent experiments of Lord 

 Rosse and M. Marie-Davy. These appear to show that the heat 

 which is received from the moon is mainly radiated, not re- 

 flected ; that the temperature of the moon's surface is about 

 500 F. ; and that the calorific effect of the full moon is only 

 equal to about one ninety-four-millionth of a degree centigrade. 

 But we must bear in mind that the greater amount of lunar heat 

 which is radiated to the earth is absorbed by the aqueous vapour 

 in our atmosphere. 



The fifth chapter discusses, among other things, the possible 

 evidence of a lunar atmosphere. All the known evidence tends 

 to prove that the moon has either no atmosphere at all, or that 

 the atmosphere possesses extreme tenuity. Sir John Herschel, 

 however, and others have admitted the possibility of the existence 

 of an atmosphere on the hemisphere of the moon which is 

 turned away from us, and this theory is based upon the fact that 

 the moon's centre of gravity is nearer to us than her centre of 

 figure. 



Among the more striking illustrations in the work are two 

 lunar landscapes, drawn by Mr. Proctor. Of course such land- 

 scapes can only faintly indicate what we may imagine an 

 observer would see if he were placed on the surface of the moon. 

 Yet as, our author observes, " we know certain facts, — we know 

 that there are striking forms of irregularity ; that the shadows 

 must be much darker, as well during the lunar day as during an 

 earthlit lunar night, than on our own earth in sunlight or moon- 

 light ; and we know that whatever features of our own landscapes 

 are certainly due to the action of water, in river, rain, or flood, 

 to the action of wind and weather, or to the growth of forms of 

 vegetation with which we are familiar, ought assuredly not to be 

 shown in any lunar landscape. But a multitude of details abso- 

 lutely necessary for the due presentation of lunar scenery are 

 absolutely unknown to us. . . . In looking at one of these views 

 (Plates XXI. and XXII.) the observer must suppose himself 



