HARDWICKE'S SCIENCE-GOSSIP. 



119 



was imported with the root, rather than that it is 

 a purely native insect. 1 have often intended to 

 ask, and perhaps I may be allowed to do so now, 

 does this insect, on its emergence from the pupa in 

 October, pass the winter in the moth or in the egg 

 state ; also if the life of the species extends over 

 three years, i.e., one winter in the pupa, and the next 

 in moth or egg stage ? The economy of the species 

 in question seems very inadequately dealt with by 

 our entomological authors. 



Green Food for Caged Birds.— My experience 

 leads me to think that it is quite right to give all 

 song-birds kept in confinement some green food at 

 every season of the year. My birds (a bullfinch 

 and a canary) have had watercresses, lettuce, and 

 mustard and cress, during the entire winter. 1 give 

 them as spring comes on, chickweed, groundsel, and 

 various kinds of salad leaves. When green peas and_ 

 fruit are in season, my feathered pets get a share of 

 each, and very fond they both are of tender young 

 peas and ripe strawberries, but I never at any time 

 give them much : seeds form their chief article of 

 food, green diet is their dessert. — Helen E. Watney. 



Canterbury Discoveries. — In his interesting 

 paper on " Our British Fritillaries," in last mouth's 

 Science-Gossip, Mr. Clifford has admitted Argynnis 

 Niobe into the list, alluding to its discovery last year 

 in Kent. I have a specimen of this butterfly, 

 obtained from Canterbury, which I have now not 

 the slightest hesitation in pronouncing an old and 

 re-set Continental insect. I should be sorry to say 

 what it cost me to secure it, whilst the Niobe mania 

 was raging. I am supported in my opinion by 

 several well-known entomologists in considering the 

 Niobe affair a fabrication from beginning to end. 

 The glowing account of its discovery may be found 

 in a leading entomological magazine, and an illustra- 

 tion of it was promised therein, but from sundry 

 revelations that transpired, the matter was allowed 

 to drop out of sight. Cucthocampa pityocampa, the 

 Processionary moth, the larvse of which it was stated 

 were found in such abundance, was another famous 

 Canterbury discovery, and just as great an impos- 

 ture. Specimens of Lathonia, Daplidice, Leucophcea, 

 Erythrocephala, all " taken near Canterbury," on 

 being submitted by me to one of our highest autho- 

 rities on insects, were emphatically declared to be 

 "re-set Continental specimens." — /. Anderson, jun. 



Expansion of Heated Air. — 1 have a small 

 circular terra-cotta fern-case, about 6 in. diameter, 

 covered with a glass 6 in. high, in which I was 

 growing mustard-seed. I heard the cracking of 

 glass, and looking round the room to see from 

 whence the sound proceeded, I found the fern-case 

 glass divided in two by a crack, and it fell in half 

 when I touched it. Could this have happened from 

 the expansion of the air ? The glass was not fixed, 

 I own, but rested tightly on the edge of the stand. — 

 R, H. Nisbett Browne. 



Cleavage of Slate. — It seems, by a notice in 

 the Saturday Review, 6th March, 1875, of a work by 

 Mr. Kinhahan, the law of rock-cleavage is not yet 

 understood. Mr. Kinhahan does not know why the 

 excessive force exhibited by cleavage should exist, 

 unless "an obscure tendency to cleavage previously 

 existed in the rocks." Will you allow me to place 

 before your readers the outline of the law which 

 produces cleavage ; there is nothing obscure iu the 

 action, it is always before our eyes. I have before 

 me a dusty road — a heavy shower washes dust into 



the pools as suspended mud. There is a current 

 through one pool, the other is still ; when the water 

 subsides, and the mud dries, one mass cracks, the 

 other exfoliates. There are two results on the same 

 material, deposited by the same force. The atoms 

 in the still pool subside vertically, under a vertical 

 water-pressure. The law of gravitation sends the 

 heaviest point downwards ; the result of this law 

 forms the mass into a fibrous condition ; as it dries, 

 it contracts : it cannot shrink across the grain, so it 

 cracks with the grain vertically into numerous 

 fissures. Wherever the adhesive condition of rocks 

 is strong enough it splits the pebbles in the line of 

 fissure, on the principle that a part is not so strong 

 as a whole. In the other pool the atoms subsided 

 horizontally, under the influence of the current; 

 they formed the grain of the mass on the line of the 

 current ; hence when this mass dried and contracted, 

 it could not cleave as the other had done, but satisfied 

 the contracting force by the exfoliation of its 

 successive surfaces into continuous sheets. This law 

 holds good all through nature. The flagstone, the 

 slate, wood, meat, all have their grains, and their 

 lines of fissure from their deposit. — H. P. Malet, 

 Florence. 



Undue Blossoming of Horse-Chestnuts.— I 

 noticed in Science-Gossip for March, 1875, that 

 your correspodent J. G. Halliday found a horse- 

 chestnut tree in blossom when in Paris last 

 September. I can state that the same thing occurred 

 in our city ; I saw three of the horse-chestnut trees, 

 in about the middle of September, 1S71, with new 

 leaves and in full blossom. But 1 found the flowers 

 much smaller than in their regular season, and could 

 find no ripe pollen in them : the leaves of nearly all 

 our horse-chestnuts began to turn yellow in about the 

 first or second week of August, and fell off early in 

 September. I examined several of the leaves under 

 the microscope and found the underside of the leaf 

 spun over with a kind of a tuft or web of a spider, 

 but could find no living insects on it. But the 

 leaves were all dry. If it should occur again this 

 summer, I will try to find the cause of it. I did not 

 hear whether the same species was affected the same 

 way in other cities and towns or not. — H. W. 

 Hollenbush, Reading, Pennsylvania. 



Sparrow v. Mouse.— In the number for March 

 (page 71) B. W. Woodward has a query on 

 this subject. It is not unusual for sparrows to 

 attack mice. 1 caught a mouse in a live trap some 

 time ago, and not liking to baud it over to the 

 teasing of the cat, I let it go free on the grass-plat 

 of my garden, and was much amused by seeing 

 several sparrows pounce upon it and buffet it, 

 screaming all the time in fury. The mouse ran 

 under a plant ; the sparrows waited for it, and had 

 a second chase, when it escaped into some bushes, 

 where its persecutors could not follow it. My idea 

 on the subject was that the mouse occasionally 

 treated himself with a new-laid egg, of which the 

 sparrows were aware, and expressed their indigna- 

 tion accordingly. — B. G. Cubitt. 



Microscopical Query. — In reply to the query 

 of "H. C Mo." in the last number of Science- 

 Gossip, may I suggest that the phenomenon he 

 witnessed was probably the effect of evaporation, or 

 that it was that molecular movement which is 

 common to all bodies suspended in fluid, which are 

 in a state of sufficiently line subdivision (see Car- 

 penter " On the Microscope," p. 184, s. 106)— or pos- 

 sibly both combined. — A. It. 



