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be some grounds for believing that it had become muchsmaller and less easy to distinguish than it was in earlierobservations. But it offers such different appearances undervarying circumstances of illumination, that the evidence is notconclusive. The same statement might perhaps be made withregard to a more recently announced discovery, viz., that anew small crater has appeared near to a well-known onenamed Hyginus. * Some valuable observations and drawingsof it, recently made by Mr. Neison and Mr. Green, have how-ever given additional probability to the supposition that it isreally a new formation.
In any case we must allow, that landslips and a gradualdeterioration and crumbling of the lunar rocks must almostundoubtedly still continue as a result of the intense alternationof heat and cold which the Moon undergoes in the successivehalves of each month ; and it is possible that processes of thisdescription, and of unusual magnitude, may have very muchaltered the appearance of Linne. We have good reason tohope that the careful attention now given to the Moon bymany painstaking observers, combined with the great telescopicpower at their disposal, and the accuracy of the lunar mapsrecently published, may before long enable us to speak muchmore positively as to the reality of such changes. But atpresent we can only say that the balance of evidence isdecidedly against, rather than in favour of, the existence ofactive volcanic action upon the Moon , and affords little proofof the progress even of such changes upon its surface as areotherwise antecedently probable.
The Moon , in fact, gives to us the impression that it isa body which has long since passed through a conditionsimilar, or somewhat similar, to that in which the Earth isat present. Since that time it has, we believe, grown colder
above a horizontal line passing by the upper edge of the circle ofArchimedes (the position of which we have pointed out in our previousdescription of the photograph), and at a distance from its centre equalto rather less than five times its diameter.
* This may also be detected in the photograph by those who knowwhere to look for it.