552 HEPORT— 1902. 



This announcement drew the attention of astronomers all over Europe both to 

 the spot itself and to the older records. It was found that, whilst the usual 

 appearance was that of the spot described by Schmidt, it was possible to make out, 

 under low illumination, a small conical hill, a minute crater, and the remains of a 

 larger shallow crater, some 4" or 5" in diameter. Lohrmann had drawn a crater 

 here which he describes as very deep and visible under every illumination. 

 Madler had drawn a similar crater, had frequently observed it, and remembered 

 having seen shadow in the interior with the sun at an altitude of 30°. Schmidt 

 himself had also seen and drawn a similar object. There was, however, found a 

 drawing of Schroter's which some have taken to represent very much what we 

 see now ; others have thought that it represents something different from this: and 

 others again that he simply omitted to draw the crater at all, similar omissions 

 being found in other drawings of his. The drawing has, however, been held by 

 many to throw doubt upon the reality of the change, although the positive asser- 

 tions of Lohrmann, Madler, and Schmidt appear to me to be conclusive. 



Another change on the surface was announced in 1877 by Klein, who found a 

 black spot, three miles in diameter, a little north of Hyginus, and therefore nearly 

 in the centre of the visible disc and in one of the best known regions of the moon. 

 Many drawings were examined, but no observation of the spot could be found 

 previous to 1876 ; subsequently to its discovery it was always a conspicuous object 

 within thirty-six hours of either sunrise or sunset. The most practised observers 

 agreed that it was due to a shallow bowl-shaped depression, and Schmidt, Klein, 

 and Neison were all of opinion tliat it was the result of an actual physical change 

 on the surface. 



There are many other iiistances of suspected change, though the evidence is 

 not so strong as in the cases quoted. 



Changes of a different character are those which are periodical in their nature, 

 the period being that of a lunar day. Some of these were known and described 

 by Madler, who rejected the opinion held by many that they were due to vegeta- 

 tion, on the ground that vegetation without air or water was beyond our compre- 

 hension. A number of these spots have been studied by Professor AV. H. Pickering, 

 who believes that the moon has sufficient atmosphere to support some possibly low 

 types of vegetation, and that the changes to be seen in such spots as those in 

 Alphonsus and Atlas are really indications of vegetable life. 



These and other instances of possible change on the surface clearly lay upon us 

 the duty of so mapping and describing every discoverable feature on the moon 

 that future generations may be able to recognise change in any part of the surface. 

 Even the best photographs show only the larger formations, those in which 

 change is least likely to be noted. The more minute detail is still accessible only 

 to visual observation, which must be prolonged over many lunations if all that can 

 be seen is to be recorded. This is too much for anyone to undertake for the whole 

 surface, but it may be done for a few formations by any amateur who will devote 

 himself consistently and perseveringly to the work, first laying down from the 

 photographs all that can be found on them, and then filling in the details at the 

 telescope with the help of a micrometer. 



3. The Relative Apj)arent Motions of Bright and Faint Stars. 

 By Professor H. H. Turner. 



1. Sir David Gill finds for zone —40° to -52° that bright stars are increasing 

 their Pv,.A. about +0'''0012 per magnitude per year with reference to faint, 

 suggesting a rotation of bright stars as a whole. This result is arrived at by com- 

 paring catalogues made by eye observations from which the effect of ' magnitude- 

 equation' has only partially been eliminated. 



2. Photographs of the same region, taken at dates sufficiently separated, would 

 show this motion without any interference from ' magnitude-equation.' 



3. The photographs taken at Oxford in zones + 25° to + 31° for the Astrographic 

 Chart, from 1892 onwards, do not yet allow of this direct method of attack on the 



