November i6, 191 i] 



NATURE 



89 



travelling southward, it is about half-way between /x and 

 e Serpentis. 



Beljawsky's comet is now fainter than the sixth magni- 

 tude, according to the ephemeris, and is three or four 

 degrees north-east of Antares ; it is practically unobservable, 

 and is apparently travelling southwards, while receding 

 from both the sun and the earth. 



The Distortion and Apparent Dilatation of Celestial 

 Objects at the Horizon. — Mdlle. G. Renaudot has an 

 interesting article on this subject in No. 2002 of ha Nature, 

 where she discusses the numerous explanations which have 

 been put forward since the time of Aristotle. Special 

 attention is paid to the explanation suggested by Alhazen, 

 which calls in an optical flattening of the celestial vault 

 causing the observer to feel that the stars, &c., are nearer 

 to him, i.e. they should subtend a greater angle than they 

 really appear to do. The interest of the article is greatly 

 enhanced by some excellent photographs, taken by M. 

 Qu^nisset, illustrating the distortion of the solar disc near 

 the horizon. 



Early Visibility of the New Moon. — Referring again 

 to Mr. Horner's observation of the new moon, Mr. Whit- 

 mell, in The Observatory, makes one or two minor addi- 

 tions to his previous results, and quotes another case, more 

 remarkable still, inasmuch as the moon's age was only 

 14-75 hours, which has been brought to his notice. Mr. 

 Hoare, of Faversham, sweeping the horizon with a 4-inch 

 refractor on July 22, 1895, picked up the crescent moon, 

 and after steady gazing was able to hold it with the naked 

 eye. In this case the difference of altitude between the 

 sun and moon was 4° 28', the former being 2° 19' below, 

 the latter 2° 7' above, the horizon, and the difference in 

 azimuth was 7° 5'. 



A New Astronomical Society and Publication. — We 

 have received one or two numbers of the Revista de la 

 Sociedad Astronomica de Espafia, the monthly illustrated 

 publication of this newly formed society. The-vreview is 

 well printed on good paper, and, in addition to the notices 

 of the society, ephemerides and phenomena for the month, 

 &c., it contains some excellent illustrated articles. 



SOM'E PAPERS ON SPIDERS AND INSECTS. 



''PO the Proceedings of the Academy of Natural Sciences 

 -^ of Philadelphia for May Mr. N. E. M'Indoo con- 

 tributes an article on the lyriform organs and tactile hairs 

 of spiders. The lyriform organs, first observed in 1878, 

 are sensory skin-structures peculiar to arachnids, and 

 consist usually of several more or less nearly parallel 

 slits, generally surrounded by a dark lyre-shaped band. 

 In the simple type there are only two or three slits, with 

 a common border ; but in the compound type there are 

 from four to thirty slits, all of which may be enclosed in 

 a common border, or each of which may have a border of 

 its own. The lyriform organs attain their greatest com- 

 plexity in the hunting-spiders, " and as these usually con- 

 tain more slits than those of the snarers or tube-dwellers, 

 we must conclude that the method of capturing food has 

 brought about these changes in the number of organs." 

 As regards iheir precise function, the author is convinced 

 that these organs have nothing to do with the sense of 

 hearing, which appears to be undeveloped among spiders. 



Owing to the rapid development and opening up of the 

 country, and the consequent introduction of enormous 

 quantities of seedlings, shrubs, trees, &c., Canada is 

 specially liable to suffer from the accidental introduction of 

 noxious insects. Accordingly, in May, 1910, the Dominion 

 Parliament passed " an Act to prevent the introduction or 

 spreading of insects, pests, and diseases destructive to 

 vegetation." A copy of this Act is published as Bulletin 

 No. r of the Entomological Division of the Canadian 

 Department of .Agriculture. 



Among destructive insects that have reached Cinad.i 

 from Europr, two of the worst are the spruce budwdim 

 {Tortrix jiiDiijennut) nnd ilw l.nc h saw-fly, the ravages of 

 which, coupli-d with ili(is( (,f dilwr insects, to forests are 

 f'Stiniati-d in a panipiil<:r l)y Dr. C. G. Hewitt, thi' 

 Dnniiiiidii ciitonioldgist, i-.su<'(I by the British VN'Iiii; riil>- 

 livhiiii4 Coinpaiiy, Kingston, Ontario, to be as serious a--; 



NO. 2194, VOL. 881 



the losses due to forest fires. Both insects are now spread 

 over large areas in eastern Canada. The former species, 

 which was first observed in force in 1909, defoliates 

 balsam and spruce, and is reported to be doing the same 

 to Douglas pine in British Columbia. Spreading like fire, 

 in the adult stage this insect extends its range in a manner 

 which cannot be controlled by ordinary means. The larch 

 saw-fly, which thrives as well on the American larch as 

 on its European namesake, was first observed in America 

 in 188 1, and two years later had spread over the New 

 England States, whence it made its way into Canada by 

 1882. It attained a great development between that year 

 and 1885, but after that practically disappeared until 1904, 

 when it once more began to increase ; at the present time 

 it is spread over an area of 2500 miles. The best hopes of 

 keeping the insect in check are centred on on ichneumon 

 fly (Mesoleius aulicus), which appears to have been intro- 

 duced for this purpose, although it is not quite clear 

 whether the author is referring to its work in England or 

 Canada. 



In the September number of The Entomologist's Monthly 

 Magazine Messrs. Porritt and Bankes give notes, illus- 

 trated by a coloured plate, of nine interesting species of 

 British insects. Among these is the moth Nonagria 

 neurica, taken for the first time in this country in the 

 Cuckmere Valley, Sussex, in 1908, the British specimens 

 hitherto referred to this species being shown to belong to 

 an allied form. The caterpillar and pupa are described 

 by Mr. H. M. Edelsten in a separate paper, also illus- 

 trated by a plate. 



A list of the Macro-Lepidoptera of the Falmouth district, 

 by Mr. W. A. Rollason, is published in the seventy-eighth' 

 annual report of the Royal Cornwall Polytechnic Society. 



I 



SEISMOLOGICAL NOTES. 



N the Bulletin de VAcademie Imperiale des Sciences de 

 St. Petersbourg, VI S^rie, October i. Prince B. 

 Galitzin adds another valuable contribution to seismometry. 

 In No. 14, 1909, of the same Bulletin he pointed out that 

 the azimuth of an earthquake epicentre can be determined' 

 from observations made at a single station. This direc- 

 tion is that of the first longitudinal wave, and is obtained 

 by taking the resultant of amplitudes recorded in two 

 directions at right angles to each other. Because hori- 

 zontal pendulums are usually oriented north-south and east- 

 west, the displacements are given in these directions. If, 

 for example, one instrument recorded 10 mm. of north- 

 south motion and the other 10 mm. of east-west motion, 

 we see that the direction of motion was N.El.-S.W., but 

 we do not know if it came from the north-east or from 

 the south-west. This is the question that Prince Galitzin 

 answers. If the front of the first wave is dilatational in 

 character this motion is towards and down to the epicentre, 

 but if it is condensational it is away and up from the 

 same. This distinction is made clear by the ncouls of a 

 seismograph recording vertical motion. Obscrvatiims have 

 shown that sometimes the first movement of thi< instru- 

 ment is upwards and sometimes it is downwards. I he 

 upward motion indicates a condensation, and the latit^- a 

 dilatation. Between July 2, 1909, and June 8, 191 1, Princt 

 Galitzin has determined the position of forty-two epicentres 

 by methods in which these rules have been fulldw.il. 



'in the issue of the same Bulletin for OcK.bn- i5\ve 

 find two more instructive communications from Prince 

 (laiilzin. The first deals with observations on the vertical 

 component of earthquake motion. In connection witii this, 

 one result, based upon the records ot ^ix l.ngc r:utlu|u,il-;is, 

 is that the ratio of the vertical and horizontal i (ini|)()nenls 

 of movement is not constant, and is less than th.U winch 

 might be c'xpecled. .Another result is based upon the 

 apparent nii-le uf emergence. Ohserv.ition-. of nin.teen 

 eartiiquakes show that those witli orij^iiis at dl-l :!nci>s 

 var\ing between 2260 and ;,S4o km. h.-ive Lii\. n \;ihies 

 for tliese angles decreasing fnim 51 degrees i.> 4.' d. -nes. 

 l'"rom this latter distance up to 1.4,(1.-,, km. the v.ihh- h.ive 

 incre;ised up Id 7i> de-ie.s. No defmile l;nv Iim" ih, 



rel;itionvllip he|«,.rn diM;m<e .ind (he .'in-le .,f elllere.nCe 



,..,,, ;,,., I),. |,,| iinil.il' il. I he -^ei niid cumiiuinieiitinii. uhicll 

 was luoiii'ht helore the .\c;i(|emv on >ei)trmh. c 21, deal- 



