278 



NATURE 



[August 31, 191 1 



typewriters may be, it is all visible, and anyone with 

 any sense of mechanics can see it all for himself and 

 understand it, and, moreover, in the larger towns at 

 any rate, there is no difficulty in finding all the better- 

 known examples, and willing expositors in the shops 

 in which they are sold. Still, it is well that the 

 subject should be dealt with systematically. 



IJssajous'sche Stimmgabelkurven in stereoskopischcr 

 Darstellung. By J. W. N. Le Heux. Pp. 8+18 

 plates [loose cards in case]. (Leipzig : Johann 

 Ambrosius Barth, 191 1.) Price 6 marks. 

 The author refers to the interest w 7 hich Lissajous 

 figures have in physics and mathematics, more 

 especially when presented in their most attractive 

 form so as to appear in stereoscopic relief. As is well 

 known, pairs of figures otherwise identical but 

 slightly different in phase appear when viewed in a 

 stereoscope (or by accustomed eyes without a stereo- 

 scope) to blend together and form a single picture in 

 three dimensions. The author discusses eighteen 

 plates as follows, three of ratio 1 : 1, five of 1:2, 

 two of 2:3, three of 3:4, two of 3:5, and two of 

 4 : 5 ratios. Some show a single line only, other-; give 

 ten or more closely spaced lines. The plates are so 

 clear that the stereoscopic effect is perfectly seen 

 without a stereoscope. 



Europe in Pictures. By H. Clive Barnard. Pp. 64. 



(London: A. and C. Black, iqii.) Price is. 6d. 

 The pictures in this book will serve admirably to 

 illustrate geography lessons in schools. The text is 

 scarcely so suitable for school purposes ; it is arranged 

 unattractively and in such a manner that the plates 

 often have little to do with the letterpress facing 

 them. 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of. rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications.] 



A Pseudo-Aurora. 



For some time 1 have been staying at the Kurhaus, St. 

 Beaten.be'rg, Switzerland, and my window commands a 

 view of the Bernese Oberland from the Wetterhorn to the 

 Balmhorn. The Eiger Monch, Jungfrau, and Rliimlisalp 

 stand out most clearly above the lower mountains in front 

 ol ili'in, uf which the Faulhd'rn and Mesen arc rnerribers. 

 Then' has been a continuance of hot and dry weather for 

 many weeks, and there have been occasional thunderstorms 

 with both forked and sheet lightning. On the night of 

 August 21, about ten o'clock, semicircular Hashes of light 

 shot up apparently behind the Monch, quivered for a few 

 seconds, and then disappeared. 1 counted twenty-eight in 

 a minute. The light was sometimes intense at a central 

 point, which was steady, and from this a quivering glow 

 proceeded anil lighted up from 15° to 20 of the horizon. 

 The outline of the Jungfrau group could occasionally, but 

 not alw.n s, I" sei n. 



The appear; seemed 10 me very like an aurora 



borealis which 1 saw in "xniland irt the 'fifth-, but the 

 centre of the light here was to the south-west of where 1 

 stood. I do not know how long the light had appi 



1 saw il, but it continued to flash with great 

 brilliancy for about twenty minutes. It then became less 

 bright, and did not shoot so high into the iky, but 1 xtended 

 laterally to the south for about 30 behind the Oberland 

 chain. After half an hour more these died away, and on 

 looking "ill two hours later nothing was to lie seen. I 

 am informed that a similar phenomenon was visible on thi 

 previous night, but was less brilliant. The resemblance in 

 a true aurora was so great that I have thought it might 

 be worth description. Lauder Rkunton. 



NO. 2183, VOL. 87] 



Rainless Thunderstorms. 



During tin long-continued drought local storms have been 

 reported here and there, and have been described as rainless. 

 Will you or any of your readers explain this phenomenon? 

 1 have always imagined that raindrops played a large part 

 in the manufacture of atmospheric electricity, but I suppose 

 that there are electrical storms in rainless countries. 



A. A. M. 



Hove, August 10. 



The point raised in the foregoing letter is one of con- 

 siderable interest in connection with the origin of the 

 electrical phenomena of thunderstorms. The fact that 

 thunderstorms are usually accompanied by clouds of a spei ial 

 character and heavy rain is common knowledge, and after 

 Wilson's discovery of the difference in the effectiveness of 

 the positive and negative ions as condensation nuclei it was 

 generally assumed that condensation produced the necessary 

 separation of the positive and negative electricity, and was 

 an essential feature in thunderstorms. Simpson in his recent 

 paper on the " Electricity of Rain and its Origin in Thunder- 

 storms " makes splashing and breaking up of actual rain- 

 drops a necessary part of the mechanism of a thunder- 

 storm. 



Published accounts of rainless thunderstorms are not 

 common, but one was contributed by Mr. E. J. Lowe to 

 Nature for September 7, 1893. He says, " On August 9 

 (at Shirenewton, near Chepstow) there was no rain bur 

 more lightning than I had seen since the memorable storm 

 of August 9, 1S43. It commenced at 9 p.m., and lasted 

 five hours. From very frequent counting there could not 

 have been less than 10,000 Hashes." 



More recently, Captain A. Simpson, of the s.s. Moravian, 

 described a thunderstorm near Cape Verde lighthouse, when 

 thei. w.i- no rain nor even lower clouds. " For fully an 

 hour the sky was one blaze of lightning, and thi 

 mast heads, vard arms, derrick ends, &c, wen- lighted up." 

 See M.O. Pilot Chart of the North Atlantic and Medi- 

 terranean, April, 1903. E. G. 



Meteorological Office, South Kensington, 

 London, S.W., August 22. 



Habits of Dogs. 



Can any of your leaders inform me whether it is common 

 for dogs 10 eat wasps, or if it is likely to prove injurious? 

 A young bulldog of mine (" Billy ") now finds his chief 

 amusement in catching flying wasps with his mouth, and I 

 think he must swallow them, as they generally vanish, 

 though occasionally I have found the corpse on the floor. 

 It seems evident from the dog's demeanour that the -line 

 makes some impression ; he shakes his head and licks his 

 lips energetically, and occasionally runs to a corner and 

 rolls on his back kicking. But the next moment he is off 

 after another. That he is not invulnerable appears further 

 from the fact that yesterday, after treading on a wasp, he 

 Tilted a paw and limped on three legs, until I applied 

 ammonia. frieri was a tender spot where the skin had 

 been grazed between the toes ; possibly the sting lit there. 



The same bulldog had another curious habit. When I 

 was on the Cornish coast he spent much of his time in 

 lolling boulders backwards along the beach or in shallow 

 water. His method was to embrace the stone with his 

 powerful fore-arms and fling it towards his hind paws, 

 licking it well over at every pause. As he generally chose 

 the biggesl stone he could well move, it was laborious 

 work : but he was tremendously enthusiastic about it. In 

 irden too, il not watched, he would drag the stones 

 from the rockery .across the lawn. This pursuit has now 

 lapsed from lacl "i opportunity, though he occasionally 

 practises on ■> straj brick or flower-pot. 



It testifies to thi hardiness of thi national breed that 

 " Hilly " was undamaged by a " head-on " collision with 

 a motor-car which he had charged. I saw him knocked 

 forward, and then struck by the wheel, hut at my cry of 

 horror he came galloping back to me as cheerful as ever. 

 I In driver had doubtless put on the brake as soon as 

 possible, for he kindly stopped a moment later to see if 

 the dog had been hurt! A. Everett. 



Woking, August 21. 



