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HARDWICKE'S SCIENCE-GOSSIP. 



distinction is that the male has each of its wings 

 edged with a black border, unbroken except by very 

 fine yellow lines that are a continuation of the veins. 

 In the female this border is broken by greenish- 

 yellow patches, varying in size in different speci- 

 mens. Besides this there is another less striking 

 difference, namely, that at the root of each hind wing 

 in the male there is a light yellow spot, of which 

 there is no trace in the female. In the Science- 

 Gossip for last December one of your correspondents 

 remarks that he noticed in a specimen of this butter- 

 fly that the hind wings were suffused with a rosy 

 purple lustre. If he will carefully examine his speci- 

 mens, he will find this apparent peculiarity is common 

 in a greater or less degree to every specimen of the 

 male insect. Those male butterflies that had very 

 lately emerged from the chrysalis would display it 

 most vividly, while in the female there is not the 

 least trace of it. — C. E. B. Hewitt, Birmingham. 



Preserving Skins. — Skins of small birds may 

 be preserved by clipping wool in carbolic acid, and 

 stuffing the birds with the same. — J. Y. 



The Mighty Deep. — In your issue for April, I 

 find a very interesting paper on this subject from 

 Mr. A. Ramsay. Will you permit me to offer to 

 him, and to your readers, a brief remark upon it ? 

 Mr. Ramsay says — "The great bulk of the sea is 

 cencentrated in the Southern hemisphere " — and on 

 the authority of several authors he gives the most 

 probable mean depth at about 2,600 fathoms. In 

 the reports from the Challenger, as published by the 

 Admiralty, Nos. 1, 2, 3, 6, and 7, the mean depth of 446 

 soundings is about 1,716 fathoms 4 feet 1 inch. I have, 

 put down in the Geographical Magazine for March, 

 page 66, the mean depth of the Northern hemisphere 

 at about 1,907, and of the Southern at 1,642 

 fathoms ; giving a mean depth all round the world 

 of 1,774 fathoms 3 feet. The two means do not 

 coincide, because I omitted certain coast soundings 

 in the latter calculations. It follows, that the 

 volume, as given by Mr. Ramsay, must be wrong; 

 and though the surface-water area is more extensive 

 in the South, the bulk of water is about the same in 

 both hemispheres. The deepest water in the North 

 is 4,575, in the South 2,900 fathoms ; in the Arctic 

 regions 1,860, in the Antarctic i,Soo. There is water 

 round the North Pole, and land round the South. 

 The equilibrium of the globe seems perfect. The 

 mean depth of the ocean, beyond coast soundings, 

 may be put down at 1,750 fathoms; very nearly two 

 miles. If Mr. A. Ramsay can turn his attention to 

 the Geological Survey report of the Winter Moun- 

 tains, as published at Washington, U.S., he will find 

 some curious facts as to the depth of water in those 

 regions in times long past. — H. P. Maid. 



The Natterjack Toad. — Can you tell me if it 

 is true that the Natterjack toad (Bnfo calamita) gives 

 forth a most intolerable odour when handled or 

 frightened ? I should be much obliged, too, if you 

 could inform me of any place near London where this 

 reptile may be met with. — y. Perrycap. 



Our British Snakes. — In answer to a ques- 

 tion put in the February number of the SciENCE- 

 Gossip as to whether our British snakes eat birds or 

 mice, I can state positively that the viper eats both. 

 In 1876 I killed a viper, which I fcund to contain 

 six young willow wrens, feathered, and within a few 

 days of flying. Past year I killed a young one, which 

 contained a large long-tailed field mouse. Can any 

 of your readers give me any information as to how 



or why the blind -worm carries its young in a case, 

 in its back, and how long this continues ? and do either 

 the viper or ringed snake do the same ? 



Remarkable Nests. — This year we have noticed 

 three curious instances of a departure from the usual 

 habits of birds in building their nests, which seem 

 worth recording. The song-thrush lines her nest with 

 cow-dung and clay ; and it is usually considered by 

 ornithologists that, as she builds very early in the 

 spring and frequently in exposed situations, the mud 

 lining protects the eggs and the young brood from the 

 fierce March winds. Early in March we found a 

 thrush's nest in our garden, containing four eggs ; but 

 the nest had not a vestige of the usual mud lining. 

 Unfortunately we found the nest destroyed one morn- 

 ing before the bird had time to hatch, so it was 

 impossible to note whether the inclement weather 

 had any effect on the eggs. We have at this moment 

 a blackbird sitting upon six eggs, four of which are 

 her own and the other two those of the song-thrush. 

 When first the nest was found it contained two of 

 each kind, a thrush having laid in the blackbird's 

 nest. Although sparrows will sometimes appropriate 

 swallow's nests to build in, and though several birds 

 will build a new nest on an old foundation, it is, I 

 think, very unusual for one species — the cuckoo, of 

 course, excepted — to make use of a nest built by 

 another species. The third curiosity in nest-building 

 is the nest of a chaffinch, placed in the fork of an 

 elder-bush near our house. Usually the chaffinch 

 assimilates the colour of her nest to the situation in 

 which she places it ; if she builds in a hedge she 

 generally covers it with green moss ; but if she builds, 

 as she often does, on the bare branch of an old apple- 

 tree, she uses the grey lichens, which are usually near 

 at hand, and covers her nest with them so skilfully 

 that though quite open and exposed it becomes hidden 

 by its resemblance to a knob or excrescence of the 

 tree itself. In this case, however, though the bird 

 has recognised the necessity of covering her nest with 

 something, she has rendered it most conspicuous by 

 sticking little bits of white decayed wood all over it. 

 The wood is so white that the nest looks almost like 

 a snowball in the branches. Possibly this bird may 

 be colour-blind, or she maybe just a little bit " want- 

 ing" in her instinctive faculties, as human beings are 

 occasionally in their reasoning powers. Why not ? — 

 Robert Holland, Norton Hill, Runcorn. 



How long can a Fish live out of Water ? — 

 A friend of mine some days since removed a gold-fish 

 from a glass globe, on account of its having mildew 

 (probably a parasitic growth of Epistylis). It was 

 placed in a basin of water at night on the kitchen 

 dresser. In the morning, at six o'clock, my friend 

 discovered the fish was missing from the basin, and 

 could be nowhere found. At past twelve o'clock at 

 noon the fish was discovered behind some plates 

 under the dresser ; as it moved when handled it was 

 placed in water, when it gradually revived, and is 

 now as lively as ever. This unfortunate fish was 

 certainly above six hours, possibly much more, out 

 of its proper element, and in my experience I have 

 never known one to survive one quarter that time. — 

 Henry Taylor, Peckham. 



Sparrow-Hawks and Windows.— On hearing 

 a dash against a plate-glass window in an adjoining 

 room, I found a sparrow-hawk lying on its back, 

 stunned, with its wings extended ; taking it carefully 

 up, after holding it in my hands for a minute I 

 placed it on its legs close by a plate of water ; it 

 gradually recovered, tried its legs, and in about ten 



