4% PHILOSOPHICAL TRANSACTIONS,. [aNNO 1665. 



such bulky masses of ice, that are far larger than the objects which we are 

 assured we can see in the moon. Again, we cut down whole forests, and drain 

 marshes, of an extent large enough to cause a considerable alteration : And 

 men have made such work, as have produced changes large enough to be per- 

 ceived. In many places also are volcanoes sufficiently large to be distinguished, 

 especially in the shadow : And when forests or great towns are on fire, it can 

 hardly be doubted, but these luminous objects would appear, either in an eclipse 

 of the earth, or when such parts of the earth are not illuminated by the sun. 

 But I know no man who has yet observed such things in the moon ;* and one 

 may be rationally assured that no volcanoes exist there, or that none of them burn 

 at this time. And to this all curious men, that have good telescopes, ought well 

 to attend. And I doubt not, that if we had a very particular map of the moon, 

 we or our posterity should find some changes in her. And if the maps of the 

 moon of Hevelius, Divini, and Riccioli, be exact, I can affirm, that I have 

 seen there some places considerable enough, where they put parts that are clear, 

 whereas I there see dark ones. It is true that if there be seas in the moon, it 

 can hardly happen otherwise than on our earth, where alluviums or new acces- 

 sions of land are made in some places, and the sea gains on the land in others. 

 I say, if those spots we see in the moon are seas, as it is commonly believed ; 

 whereas I have many reasons for being of a contrary opinion. And I have 

 sometimes thought whether it might not be, that all the seas of the moon, if 

 there must be seas, were not on the side of the other hemisphere, and that for 

 this cause it might be that the moon turns not her axis, as our earth, in which 

 the lands and seas are, as it were, balanced. This also may be the cause why 

 there appear not any clouds there, nor any vapours considerable enough to be 

 5seen, that are raised from the earth; and that this absence of vapours may also be 

 the reason that there is no twilight there, as it seems there is none, I myself 

 at least not being able to discern any : For I think the reputed inhabitants of 

 the moon might see our twilight, since it is much stronger than the light 

 afforded us by the moon, even when full ; for a little after sun-set, when we re- 

 ceive no more the first light of the sun, the sky is far clearer than it is in the 

 fairest night of the full moon. And since we observe in the moon, when she is 

 increasing or decreasing, the light she receives from the earth, we cannot doubt 

 but that the people of the moon should likewise see in the earth the light with 

 which the moon illuminates it, with perhaps the difference there is between their 

 magnitude. Much more then should they see the crepuscular light, being, as 



* Such things have of late been observed, in consequence of the great improvements in telescopes 

 by Dr. Herschel : thus verifying the speculations of the ingenious French astronomer. 



