STAR CHARTING. 21 J 



and just as in the case of the nebula in Orion, the nebula with its vast 

 folds is shown to extend farther from the centre with each increase in 

 the time of exposure, so I find with that about Eta Argus, only the 

 southern nebula is very much more difficult to photograph ; and I 

 think it must have some tinge of colour in it, probably yellow, while 

 that in Orion is green, for a photo of Orion with one hour's exposure 

 is more dense than one of Eta Argus with six hour's exposure. 

 Taken as a whole the nebula about Eta Major covers a much larger 

 space than that about Orion, even in these photographs, which 

 indicate that although the southern nebula was longer exposed it is 

 comparatively under exposed ; for the central parts of Orion are much 

 over exposed. I have also brought to show you two photos of the 

 moon, taken on 19 th and 28th of May last. As you are all aware it is 

 extremely rare to get a night in which there is absolutely no motion 

 or what is called twinkle in the stars, or in other words, when the 

 earth's atmosphere is not disturbed by currents of unequal tempe- 

 rature. Now until we get such a night and a suitable moon it will 

 be impossible to get a perfect photograph of the moon, for any motion 

 in the air such as that referred to has the effect of enlarging every 

 point of light. For instance, a star image may be made two or three 

 times its normal size, and if the stars are close together they are run 

 into one blotch. So on the moon, all the little details are enlarged 

 and mixed up, so that they cannot be seen. But these photos are 

 very good, and show some features of the moon's surface which I have 

 never seen in any other photograph — for instance, the undulations on 

 the surface of the lunar plains — the equivalent to what we should call 

 hills and valleys, as opposed to mountains. 



REVIEW. 



The twenty-second volume of the Transactions and Proceedings 

 of the New Zealand Institute, although bearing the usual imprint 

 "Issued May, 1891," has only recently been distributed to the 

 members, and consequently an opportunity has not offered of noticing 

 the contents in this magazine until the present issue. 



A considerable proportion of the papers are on zoological 

 subjects and the matters noted form a considerable addition to our 

 knowledge of the interesting fauna of New Zealand. Mr. Maskell 

 not only adds considerably to the already long list of native coccids, 

 but describes and figures species from Australia and Fiji. I notice 

 that Mr. Maskell states that the fire at the Government Printing 

 Office destroyed nearly all the remaining copies of his book on the 

 Scale Insects of New Zealand, issued in 1887. Those who have the 

 good fortune to possess a copy, should take care of it. 



Another paper on a pest too well known to fruit growers — the 

 Codlin moth — by Mr. G. V. Hudson, points out the lines on Avhich 

 observations are required to grapple thoroughly with this serious 

 nuisance. Mr. Hudson has also worked up the long.neglected New 

 Zealand glowworm and the Cicada;. Mr. Jas. Hudson records two 

 observations on Coccids in the Nelson district. 



