110 



SCIENCE-GOSSIP. 



[June 1, 1866. 



NOTES AND dUEEIES. 



Coccinellid^e, [Bibliography). — For papers and 

 memoirs oil this group of Beetles, " Eiima " is 

 referred to Westwood's Introduction, vol. i. pp. 

 395 ; Hawarth in Trans. Entom. Society, vol. i., 

 1S07 ; Schonherr Synon. Insect. _ vol. ii. ; Gyllen- 

 hall Insect, suec, vol. iv. ; Milne in Zoolog. Journ., 

 No. 2 ; Brahm in Der Naturforscher, st. 29 ; Buch 

 in Berlin Naturforsch Mag., vol. iii., 1S09 ; Sch- 

 neider in Mag. fur Entom., vol. i. ;' Erohlich in der 

 Naturforscher, st. 2S ; Paykull in Act Holm, 17S9, 

 179S ; Ann. Soc. Ent. de France, torn, i., p. 233 ; 

 Kirby & Spence, vol. i. and vol. ii., p. 9 and 230 ; 

 Gardener's Magazine, vol. iv., p. 159, 415 ; De Geer 

 Mem., torn, v., pi. 10, 11, &c. 



Dipper Walking under TVater. — I have 

 raised quite a storm of criticism about the water- 

 ousel bv my last letter. One gentleman describes 

 its "walking" very minutely, and if the other two 

 gentlemen, that wrote about the subject, ever saw 

 the bird go through such a performance, they must 

 have been very much astonished. None of the 

 correspondents, however, condescend to answer my 

 argument, and I will, at once, give three reasons 

 against the so-called walking : — First, It is well 

 known that the bodies of all birds float on the 

 water. Secondly, I am convinced that birds are obliged 

 to make great exertions wth their wings and feet 

 in order to be able to reach the bottom. Thirdly, I 

 am satisfied that as soon as they have arrived at the 

 bottom of the water, the force which enables them 

 to descend to it ceases to act. Consequently, I 

 infer that the body of a bird, impelled _ to the 

 bottom by the aid of feet and wings, must rise again 

 when deprived of that aid. I maintain, positively, 

 that a bird cannot, by any chance, icalk on the ground 

 under water. The moment it attempted to do so, 

 the legs and wings, by the altered position of the 

 body, would be deprived of all depressing power, 

 and the body itself would be raised up towards the 

 surface of the water. These arguments clearly 

 prove to me that the so-called walking is impossible. 

 And now, a word in conclusion, as to Mr. Morris' 

 statement — did he ever himself see the bird walk 

 underwater? I have seen many of these birds, 

 both in Yorkshire and Northumberland, but have 

 to meet the first yet that walks on the ground 

 under water. — Geo. F. Smith, Durham. 



Silvering Mirrors (reply to E. F. TV.)— The 

 operation of silvering a curved surface of glass 

 requires rather dexterous manipulation. The 

 simplest method 1 can describe, is as f ollows : — 

 A cast in plaster of Paris must be taken from the 

 surface that is to be silvered. This may be easily 

 done, by surrounding the edge of the glass with a 

 border of stiff paper, and pouring the plaster, mixed 

 with water to the consistence of cream, into the 

 mould thus formed. The glass should be slightly 

 greased, to prevent the plaster adhering 

 to it. When the plaster has set, say in about 

 twenty minutes or so, the paper may be stripped off 

 the edge, and the cast removed by cautiously warm- 

 ing the glass over the flame of a spirit lamp. A 

 piece of tin-foil must then be laid on the face of the 

 cast, and rubbed down smoothly upon it. The 

 creases which will be made upon the foil may be 

 readily obliterated, by rubbing with an ivory paper- 

 knife or the thumb nail. When the tinfoil is quite 



smooth, a small globule of mercury is to be spread 

 oyer it_ with a tuft of cotton wool. The mercury 

 will quickly amalgamate with the tin, and the oxide 

 and any dirt which may be present, will float upon 

 the surface. _ A piece of the thinnest tissue-paper 

 procurable, is now to be laid upou the amalgam, 

 and the glass, which must be perfectly clean, laid 

 upon the paper. A moderate pressure must then 

 be applied to the glass, and the paper carefully 

 drawn out from between the glass and the amal- 

 gam, bringing with it all the oxide, and any air or 

 dirt that may be there. The plaster cast must then 

 be cautiously removed, and the glass stood upon its 

 edge for a day or two, to allow the superfluous 

 mercury to drain out. If E. E. TV. is unsuccessful 

 in silvering his mirror, I shall be happy to tell him 

 where he can get it done at a trifling expense. — 

 Richard Pearson. 



Pat-Tail Venom. — Having been staying in 

 Norfolk for several weeks, I find that the people 

 there have a curious notion that the tail of the rat is 

 venomous. Not having heard of such a thing before, 

 I thought it might interest some of the readers. — 

 R J. J. 



The Black Pat. — A colony of these most 

 destructive animals have established themselves 

 in a granary on the Thames, where also the brown 

 rat dwells. I always understood that the two 

 waged war whenever they came into contact, which 

 generally ended in the extermination of the black ; 

 but, instead of this, the black rat seems on the 

 increase. Are they not now rather rare in England ? 

 — C. A. J. [Is our correspondent certain of its 

 being the black rat (Mus rati us), or only a black 

 variety of the brown rat ? The true black rat is 

 becoming rare in Europe. — Ed.] 



Bombtx Cynthia. — I am possessed of two very 

 fine chrysalis of the above moth — that is, from the 

 Ailanthus silkworm, acclimatized in Devonshire — 

 as I am afraid, both the perfect insects may perhaps 

 be of one sex. I should be happy to hand them over 

 to any gentleman similarly situated, so as to ensure 

 proper copulation, with a view to receiving a share 

 of the eggs afterwards, or I would myself take 

 charge of other chrysalis with my own. — Address 

 N., care of Wilson fy Sons, 103, Cheapside. 



The Toadstone.— Many old writers refer to 

 this stone. Albertus Magnus, who wrote about 

 1275, seems to be a reliable authority. He was 

 very fond of the natural philosophy of his day, and 

 was the tutor of St. Thomas Aquinas. He mentions 

 toadstone having the figure of the toad upou it, 

 when taken out of the toad's head. Others have 

 doubted this fact, and suggested that the figure 

 might be artifically produced. Teuton, writing in 

 1569, says, — " There is to be found in the heads of 

 old and great toads, a stone they call borax or 

 stelon, used as rings, which gives forewarning 

 against venom." Lupton refers to it as an antidote 

 to the poison of venomous stings. Lyly refers to it 

 in his Eupuhes ; Ben Jonson in " The Fox," scene 

 3d, does so also. Yet all that we can tell of mediaeval 

 lore will scarcely be conclusive to the present scientific 

 world, without actual modern experiment upon an 

 "old and great toad." This wouldnot be so useless 

 as many scientific experiments are ; for it is quite 

 possible" that this borax, or stelon, or crepandina 

 (toadstone), may be allied to the famous bezoar or 

 snakestone. — F. L. 



