July 1. 1893.] 



KNOWLEDGE 



129 



the bird is upon the tree, is invariably kept touching the 

 bark, never being Hfted from it. 



The tree creeper is very shy, and rarely allows itself to 

 be seen for any length of time ; for although it does not 

 seem to be watching, it quickly places itself on the side of 

 the tree furthest from the observer. 



Unlike the nuthatch, the creeper does not, as a rule, 

 descend a tree, and on no occasion does it descend head 

 foremost. I have, however, seen one, while in the act of 

 pulling out a piece of touchwood from an old oak, take 

 several steps backwards. 



The flight of this bird is undulating, and is generally 

 confined to short journeys from one tree to another. It 

 utters a small, high-pitched note, often repeated, resembling 

 the syllable " twee." 



The food of the tree creeper is composed of small 

 beetles, larvas, spiders, and other insects, which infest the 

 bark of trees. 



The beak is about as long as the head, and, being curved 

 and slender, can be thrust into the crevices of the bark to 

 extract the lurking insect. It is not formed for tapping 

 the tree like those of the woodpecker and nuthatch, and 

 is never used for this purpose. 



On account of the shape of its beak, together with its 

 arched back and tail, the tree creeper, when seen from 

 the side, assumes in general outline almost the form of a 

 semicircle. 



The nesting habits of this species are interesting. They 

 sometimes build in a hole of a tree, but more usually 

 between the bark and trunk of a decaying tree, where the 

 bark has slightly parted from the trunk and forms r, 

 narrow crevice. The birds creep into this crevice, which 

 is often not more than half an inch in width, and build 

 their nest in it. One would suppose that the nest would 

 be fixed to the tree itself, but such is not the case, for if 

 the bark be taken off, the nest will adhere to it. 



The nest itself is a handsome structure composed of fine 

 twigs, grass, and chips of touchwood built in layers one on 

 the top of another. It is lined with wool and feathers, and 

 varies in size and shape according to the crevice or hole 

 in which it is built. 



The tree creeper usually has two broods in the year 

 and lays from six to eight eggs at the first, in the month 

 of April. It seldom lays more than five eggs at the 

 second brood. The eggs are white with a few red spots, 

 which are sometimes confined to the thick end of the 

 eggs. They are almost identical in size and colour to 

 those of the great tit {Puriis iiiitjnr). 



Both birds take their turn at sitting, and the young are 

 hatched m about thirteen days. The birds sit very closely 

 and may even be caught on the nest. 



THE GREAT PLAINS ON THE MOON. 



By A. C. Rany.-^rd. 



THE plate which illustrates this article has been 

 made from a very beautiful photograph given me 

 by Messrs. Paul and Prosper Henry, for the use of 

 the readers of Knowledge. The photograph was 

 taken on the evening of the 28rd of March, 1893, 

 when the air was exceptionally steady — a condition which 

 seems to be of far more importance for successful lunar 

 photography than mere clearness of the atmosphere. 

 It will be noticed that most of the chefs-d'anivrc of the 

 Brothers Henry in lunar photography have been obtained 

 in the months of March and May, during the evening 

 hours when the new moon has a considerable altitude above 

 the horizon. The station from which these beautiful 



photographs of the moon were obtained is in tlie grounds 

 of the Paris Observatory, which is now surrounded by 

 houses and factories, that give rise to a good deal of smoke, 

 which generally lies within a few hundred feet of the 

 ground, and is very recognizable from the grounds of the 

 Observatory, but it is still more strikingly visible, even on 

 a clear day, from the top of the Eifl'el Tower, where it 

 may be seen as a whitish, hazy canopy hanging over Paris 

 and its outskirts. It seems that the best photographs of 

 the lunar details are obtained when the rays of the moon 

 plunge most perpendicularly through this hazy screen — 

 and that the screen adds to the steadiness of vision, for 

 such sharp photographs have not been obtained during the 

 morning hours when the canopy of smoke has been partly 

 rolled away by the night winds. 



Some of the best photographs taken by the Brothers 

 Henry show remarkable details in the lunar plains, indi- 

 cating the existence of partly submerged craters and low- 

 lying ridges, which hardly throw any shadow even when 



b^ 



'jUS: 



t ffO' 



I the sun is rising upon the lunar landscape. They are, 

 j probably, not due to mere differences of coloration in the 



lunar surface, for they are lost sight of as the sun rises ; 



while the bright streaks radiating from some of the lunar 



