HARDWICKE'S SCIENCE-GOSSIP. 



165 



Archaean rocks, the antiquity of a schist is in direct 

 ratio to its degree of crystallization. I do not say 

 'degree of alteration,' because this would involve a 

 theory, and introduce complication." For the 

 suggested law he does not claim more than an 

 empirical and local value. He starts with the propo- 

 sition, "that in Britain there occur (at least) two 

 Archaean groups, of which the older is coarsely 

 crystalline, and the younger either eruptive or 

 hypocrystalline. These are the Hebridean and the 

 Pebidian." After giving evidence from Shropshire, 

 Anglesey, North and South Wales, and (in some 

 detail) from Ireland, Dr. Callaway says that while 

 some regard Archaean studies as barren and un- 

 promising, he thinks they open out fruitful fields of 

 labour, and that workers at them "are working at 

 the great question of the origin of the crystalline 

 schists, and striving to throw light upon some of the 

 earlier chapters in the earth's crust." 



NOTES AND QUERIES. 



A Pair of Comets.— The "West Briton" (Truro) 

 of January 8, contains the following letter : — Astrono- 

 mers have rarely witnessed the appearance of a pair 

 of those mysterious travellers of the starry depths, 

 hand in hand, or like the Siamese twins, Eng and 

 Chang, hip by hip. But Bodmin last week offered 

 a favourable situation from which to observe such a 

 rare phenomenon, and for the sake of those who 

 were inconveniently placed I send a few notes which 

 I shall be glad to compare with any taken by brother 

 amateurs. I first noticed the twins in the darkest 

 part of the northern heavens. The path was one of 

 more than usual eccentricity, and the pace a headlong 

 one. Donati's comet in 1858 passed round his solar 

 majesty superbly, and assumed the most graceful 

 curves. But, on the contrary, each of the pair in 

 question, on nearing the sun, was visibly agitated, 

 and underwent a series of remarkable contortions. 

 If, for convenience' sake, we term one B, and the 

 other C, then on attaining the point of nearest 

 approach to the sun, C threw out three separate and 

 distinct tails, in one of which B got entangled and 

 finally disappeared. When receding, each tail in 

 turn faded and was lost to view, . . . The nucleus 

 of each and of the affiliated mass was of the usual 

 ethereal lightness, and stars of small magnitude were 

 distinctly visible through their very centres. My 

 observations go to confirm the beliefs that, first — no 

 cometic substance is sufficiently dense to visibly 

 disturb the sun or any of his satellites ; and second — 

 no cometic substance can too nearly approach the sun 

 or his satellites without sustaining loss or harm. — 

 Arcturus, The Observatory, Bodmin .Beacon. 



Is the Water-Ousel an Enemy to Fish ? — I 

 think it may be well to direct your readers' attention 

 to a very emphatic declaration on this point, in the 

 latest volume (orn-pht) of the new " Encyclopaedia 

 Britannica," produced early this year. The descrip- 

 tion of the dipper (article "Ousel") contains the 

 following passage : "By the careless and ignorant it 

 is accused of feeding on the spawn of fishes, and it 

 •has been on that account subjected to much 

 persecution. Innumerable examinations of the con- 



tents of its stomach not only have proved that the 

 charge is baseless, but that the bird clears off many of 

 the worst enemies of the precious product." This 

 decided statement, in a work of such authority, ought 

 to be warmly welcomed and widely circulated by all 

 friends of the mysterious little bird whose character 

 it tends to re-establish. Nearly all modern naturalists 

 have repeated unhesitatingly that the dipper is a 

 great destroyer of fish-spawn, and I am afraid nearly 

 all river-fishers are strongly prejudiced against it, one 

 of the most interesting and easiest to exterminate of 

 all our native birds. Can any of your correspondents 

 say whether the dipper ever touches seeds of any 

 kind ? From its relationship to the thrushes, I should 

 have suspected that it might occasionally prove a 

 berry-eater ; and the scarlet fruit of the cuckoo-pint, 

 to which "birds of the thrush-kind" are supposed 

 partial, is sometimes extremely abundant along the 

 banks of a dipper-haunted stream. Considering how 

 few of our non-migratory birds are purely insecti- 

 vorous, it seems difficult to imagine so aquatic a species 

 as this ousel would abide our bitterest winters 

 without some capacity to digest vegetable food. — 

 C. B. Moffat. 



The Clouded Yellow {Colias edusa). — In 1877 

 this butterfly appeared very abundantly in the neigh- 

 bourhood of Louth, frequenting the banks by the 

 roadsides, the railway cuttings, and other similar 

 situations. But, I believe, not a single specimen has 

 been captured or seen here since that year. Will 

 some reader of Science-Gossip kindly inform 

 me whether this insect has been plentiful in any of 

 the more northern counties of England since 1877? 

 And what were the "Edusa years" prior to that 

 year ? — // Wallis Knv, Louth. 



Caterpillars feeding by Night. — Very many 

 caterpillars, principally belonging to the Noctuina 

 group, feed solely at night, or very early in the 

 morning, before the sun is up. I have noticed that 

 the larvae of the carpet moths (Melanippe) are 

 nocturnal feeders, but some, at least, of the Geometrina 

 feed by day, and most of the Bombycina do so 

 likewise. I do not think it is an invariable rule that 

 butterfly larvae show a preference for feeding in the 

 daytime. I am rather inclined to think that all 

 caterpillars feed at night, those of butterflies as well 

 as those of moths.— A Ibert Waters. 



Water Voles. — Mr. J. A. Wheldon says : " I 

 don't wish for one moment to say that a vole would 

 not touch a piece of flesh if it could get nothing else, 

 though that remains to be proved. I should think it 

 need not long remain to be proved, for if some 

 practical naturalist who can obtain a water vole for a 

 day or two would do so, he would soon elicit proof, 

 without any great amount of pain to the animal. I 

 would have done it myself, but unfortunately I am 

 not in a position to get hold of a vole. Our old 

 Yorkshire proverb says, " an ounce of doing is worth 

 a ton of talking." — H. Snowden Ward. 



Cats and Kittens. — I shall be glad if any of the 

 readers of Science-Gossip can tell me if the following 

 is usual or no. Our cat lately had four young ones, 

 three of which we destroyed, and a kitten of hers, 

 about a year old could not bear the sight of the new 

 animal, would not feed with the old one, or come near 

 it, or any of us. About three days afterwards she sud- 

 denly took a turn, came and played with the kitten. The 

 three slept together, and now the young one is acting 

 the part of guardian, and is more motherly than the 

 mother (this young kitten has had none of her own). 



