20 REPORT— 1870. 



day, 365 values of half-tide level were obtained for the year, varj-iug from 25 inches 

 above the mean to 10 iuehes below, or to a total extent of 35 inches. These 365 

 values were tabulated and grouped successively as follows : — 



1st. The averages for the calendar months respectively were obtained. These 

 do not indicate any sensible annual or semiannual tide. 



2nd. The same figures were next grouped according to the limations, so as to 

 obtain the mean height for every day of the moon's age. The figures showed that 

 there was no sensible tide following tliese periods. 



3rd. Next they were grouped according to the declination, so as to obtain the 

 mean height on the days when the moon was crossing the equator from north to 

 south, and on each successive day till she returned to the same position. From 

 this it appeared that the water was slightly higher when the moon was in north 

 than when she was in south declination; and a similar result was obtained by 

 treating the values for the year 1867 in the same manner, but the difference (1| to 

 2 inches) was too small to justify any conclusion. 



4th. The^ were then grouped according to the moon's distance from the earth. 

 The means for 1868-69 showed a slight elevation when the moon was near apogee, 

 and a depression when near perigee ; but this result was not confirmed for 1867. 



From these trials it was concluded that there were no sensible tides of long period 

 due to solar or lunar influence, and that the causes of the variations must be sought 

 for elsewhere. So far, however, the result has been only negative. The range was 

 too great to be attributed to atmospheric pressure, and the want of any persistent 

 elevation during the south-west monsoon showed that they could not be attributed 

 (directly, at least) to local winds. 



An extraordinaiy rise took place in June 1869 to the extent, when at the maxi- 

 mum, of 25 inches. The sea-level was unusually high for about seven days, during 

 which there was gi-eat heat and an unsettled appearance in the weather, but no de- 

 finite atmospheric disturbance. A similar effect was observed at about the same 

 period in 1868, but not in 1870, 



ASTEONOMX. 



On the Present State of the Question relative to 'Lunar Activity or Quieseenee. 



By W. R. BiRT, F.B.A.S. 



From the time of Schrciter the question of change on the moon's surface has 

 been more or less agitated ; the ' Selenotopographische Fragmente ' contain nume- 

 rous instances of what he considered to be changes of a temporary character, and a 

 few of a more permanent nature, as the formation of new craters. It is, however, 

 notorious that he failed to establish the fact of a decided change in any one 

 instance ; nor is this to be wondered at when we consider the paucity of the mate- 

 rials he had at his command. Notwithstanding the comparative neglect into which 

 the observations recorded in the 'Fragments' have fallen and the judgment passed 

 upon them bv some of the best known selenographers, there can be no question 

 that they embody the results of zealous and persevering attention to the moon's 

 surface, and ought not to be parsed over in the examination of any gi^-en spot the 

 history of which we are desirous of becoming aquainted with during the earliest 

 pei'iod of descrijjiioe observational selettography. 



The labom-s of Schroter's successors, Lohrmann and Beer and Madler, have 

 added gi-eatly to the number of objects, either as delineated on their maps or 

 referred to in their letterpress. Lohrmann appears to have carefully studied 

 Schroter's results, as we find him quoting the measures obtained by Schroter in 

 several instances. On examining the results of the two greatest selenographical 

 works of the present century and comparing the one with the other, we find pre- 

 cisely the same kind of phenomena presenting themselves, which in a great measure 

 perplexed Schroter ; but as Lohrmann and Madler worked independently of each 

 other, and Madler evidently had a very low idea of the value of the preceding 

 labours of Schi-oter, these phenomena passed unnoticed at the time. Upon consult- 



