THE PLANET MERCURY.

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circulation) that the dates at which the supposed observationsof which we are speaking have been made, would require theexistence of at least four such planets. In the lecture in ques-tion, we have referred to nearly all the more important of suchrecords, including one which is specially interesting to citizensof London , as it was made in the year 1847, by Mr. BenjaminScott, now the Chamberlain of the City, whose observationwas confirmed by a simultaneous and perfectly independent oneby the well-known optician Mr. Wray.

The most celebrated instance of all is, however, that ofLescarbault , of the date of March 26th, 1859, in which the greatLe Verrier seems to have put much faith. But Lescarbault ’ssupposed planet has never been seen again, although often verycarefully looked for, in the months of March and September,and especially in years when the calculations of Le Verrier ,made from Lescarbault ’s original statement, show, that, if itreally existed, it ought certainly to have appeared in transit.

Upon the whole, therefore, we can only say that it is veryremarkable, that, if any of such observations have not beendelusive, no recurrence of the transits has been detected. Onthe other hand, it is also surprising that so many observersshould have been deceived, although it must be confessed thatthey have not all enjoyed the advantage of long and practisedexperience in observing. It is moreover certain that someapparently well-authenticated cases have been subsequentlyproved to have been erroneous.*

The question of the existence of intra-Mercurial planets istherefore still an open one, and of great interest. It isessential that, for some time to come, especial arrangementsbe made for the very careful examination of the sky, in theimmediate neighbourhood of the Sun, during total eclipses. Ifany such planets exist, this appears to be the most likelymethod for their successful detection’.

In connection with this remark, we may mention,f that

* See an article by Professor Peters in Astronomische Nachrichten ,No. 2254 ; also one by M. Tisserand in the Annnaire (In Bureau denLongitudes , 1882.t See Nature, vol. xviii., p. C63.