60 



• KNOWLEDGE 



[Nov. 18, 1881. 



(©utrifsf. 



[ U I LocAiUTiiMs. — Will you kindly etiito (lie Ijcst rlienp " Tnblo 

 iif I,of{iirilliin« iinil Antilognrilliiiifl," Ar., mitablp for a gpiioral 

 m'icniM' Rtiidriit, biU moi-o cspcciiilly for one piopariiiK for pxanii- 

 iiiiliiin ill '• niino siirviyinp," in cunnpction with thi' City nnd Guilds 

 of London? llo woul<l observe tlmt he bns Hecn a book of tables 

 iidvortiBed nt '^s., nml written by W. C. Unwin, and if you think 

 that will bo <|Uito Huitable, " yo8 " op])Osite the initials will be 

 deemed a suflioient answer. 'Die writer was intending to purchase 

 the above book, but on reading your remarks on logai-ithms in 

 No. 1 of K.vowLEDGE, determined to seek your advice. 



Jameo Grindv. 

 [ Wc n.se ourselves Chambers's " Tables " for ordinary work, and 

 llnlton's when certain subsidiary tables arc required. We have not 

 used the work named above, but probably some of our readers can 

 give Mr. (irundy the information he rc<piircB. — Ed.] 



[lij — 1.1 it possible for the same star to be both morning and 

 evening star on the same day ? Does not Tennyson's Ilesper — 

 Phosphor refer to the same star at different periods of its month ? — 

 |{. A. Bri.t.EX. [To the first question, No; to the second, Yes, only 

 for month should bo written synodical period, meaning the period 

 in which the planet goes tlirough all its apparent movements with 

 respect to the sun, from being in conjunction vrith him to its next 

 return to that position. — Ed.] 



[13] — Watek Sphkroids. — If a little water is spilled from a 

 lieight of a few feet upon a surface of smooth water, a portion of 

 the Huid, instead of mixing with the rest at once, is formed into 

 small globes or spheroids which, I think, seldom if ever exceed 

 i inch in diameter, most of them being very much smaller. Tliese 

 little drops move over the water for distances varying from a few 

 inches to a few feet, and then gradually though rapidly diminish 

 and disapjicar. 



In explanation of this reiy common phenomenon, I have been 

 informed that a layer of air of greater density than the atmosphere 

 is formed over the surface of the water, and that the part of this 

 layer between the globules and the plain surface of water offers so 

 much resistance that for a time the two bodies of fluid are unable 

 to unite. It would be interesting to know what causes this denser 

 layer of air, and why it is only for a time able to overcome the force 

 of gravity acting upon the spheroids. — E. C. 1{. 



[11] — Velocity of Socnd. — 1 understand Tyndall to say that 

 the increase of temperature in the condensed part of a sonorous 

 wave augments its velocity one-sixth. Is the increase gained by 

 the rise of temperature in the condensed portion not counter- 

 balanced by the decrease of temperature in the rarefied part ? — 

 Socnd. 



[15] — The Missing Link. — What is the " missing link," of which 

 we hear so much in connection with Mr. Darwin's books ? Is it 

 rtliat should come between an ape and a man ? An answer on this 

 ]ioint would much oblige — An Ignoramus. 



[10] — German and English. — Is there any work where I can find 

 an account of the progi'ess by which the English and German lan- 

 guages have come to differ so widely in character from each other ? 

 In good English ^n■itingwe find the arrangement of subject, predi- 

 cate, Ac, quite different from that adopted in good Gcrm.m wTiting. 

 Vet the languages had a cognate origin, and must once have re- 

 sembled each other somewhat closely in those jioints in which they 

 now differ. Strangely, too, while the Gcnn.an langu.ige has become 

 in stniclurc less simple than the English, tlic German words for 

 abstract ideas, and their scientific terms, arc much simpler than 

 ours. When wo speak of oxygen, a German speaks of sour-stuff j 

 l>ut where an English wi-itor would say that a mixture of oxygen 

 and hydrogen will ex])lodo, under such and such conditions, a 

 ficrman would say that soiu'-stnff and wasser-stuff, in certain pro- 

 portions mixed, and under certain conditions so-and-so treated, 

 explode shall. — Eclecticus. 



[17] — RETROGRAnATioN OF A Planet. — 'Wliich planet has the 

 longest arc of retrogradation ? And on what circumstances does the 

 length of the arc depend ? — Astronomiccs. 



[18] — Chemical Tbe.\tises. — Can any reader of Knowledge tell me 

 what hooks will give mo the best general idea of the so-called new 

 chemistry ? 



Arctic Navigation. — Advices from Copenhagen state that the 

 news received from the Dutch Polar Expedition on board the 

 schooner iri/iiam Barents is very unfavourable. Owing to the con- 

 tinuous ico barrier which extends nearly to Norway, Spitzbergen 

 could not be reached, nor even the Bear Islands; and after one 

 more attempt to force through northward, theexpedi(ion will return 

 home, o-s the captain is convinced that this year Nova Zembia is 

 completely enclosed in a bnirier of ice. 



3^fplif«5 to ©ufrieg. 



[1]- Ultima Tuile.- The exjireBiiinn '■ Ultima Thu'e" occur- 

 in Seneca's " Medea," Act. iii., verse 375: — 



Venient annis 



Sirciila scries, qiiibus oceaKUs 

 Vincola rerum laxet, et ingens 

 I'atcat tcllas, Typhisquc novos 

 Dctegat orbcs ; nee ait tern's 

 Ultima Thole. 

 The passage has been quoted to show that the an>'ienia had lie ir I 

 of the New World, as our school books call the ancient continent if 

 America. It seems, however, to prove rather the revorse, a^ 

 showing that Thule (whether "Tliule were Iceland or one of th ■ 

 Orkneys, Shetlands, or Hebrides) was, in Senoc.Vs time, regardi- 1 

 as the remotest-known region of the earth. — X. Z. Z. 



[1] — Ultima Tiiile. — Pytheas, a citizen of Massilia (Marseille^), 

 prcWous to the time of Alexander the Great, undertook a voyaj." 

 of discovery to the far north. The regions discovered by him wi r> 

 enveloped in fog and "chaos" and uninhabited, lie designatcl 

 the farthermost limit of his discovery Thule, whence " Ultima 

 Thule." llie actual identity of Thnle is shrouded in mystery. Oi 

 Jutland, Shetland, Norw.ay, and Iceland, each claims iirccedonco :>- 

 the Thule of Pytheas. Speaking offhand, I believe Pliny uses tlm 

 expression " Ultima Thule." I cannot recollect the way in which 

 he used the term. Some imagine Thnlc as a creation of the pixt- 

 to express the extreme limit of the world. — W. G. Kolfe. 



[1] — Ultima Thule. — If your correspondent is a classic u 

 scholar he may refer to Ptolemy, Tacitus, and others. Pliny 

 describes it as "an island in the northern ocean discovered i.y 

 Pytheas after sailing six days from the Orcadcs." I tiuote il •■ 

 following from Brewer: — "Called by Drayton, Thuly. Pliny, buW- 

 nus, and Mela take it for Iceland ; others, like Camden, consider ii 

 to be Shetland, still called Thylens-el (Isle of Tliylii) by seamen, in 

 which opinion they agree with Marinus and the descrijjtion of 

 Ptolemy and Tacitus." Bochai't says it is a Syrian word, and tlui 

 the Phoenician merchants who traded to the group called it Gczir;u 

 Thule (Isle of Darkness) ; but probably it is the Gothic Thule, 

 meaning the " most remote land," and is connected with the Greek 

 telos, the end. 



Where the northern ocean in vast whirls, 



Boils round the naked, melancholy isles of farthest Thule. 



Thomson, " Autumn. ' 

 Thule was the most northern part know>i to the ancient Roman.^^. 

 Tibi serviat ultima Thule 



ViitoiL, " Georgics " i., 30. 

 — R. T. WniGUT. 



[3] — Flight of Birds. — If " Aerial " considers for a moment the 

 very small proportion the bones of a bird bear to its bulk, and the 

 still smaller cavities he speaks of, 1 think ho will see that the 

 heated air the latter contains can but very slightly assist the bird's 

 flight, or rather bnoyanc}' ; besides which, the heat of a bird wouM 

 only cause a slight expansion of the enclosed air. Is " Aerial" sun' 

 the bone cavities do contain air, and not some gas I' — E. C. R. 



[3] — Flight of Birds. — The flight of birds cannot be aided in 

 any appreciable degree by the presence in the air-passages of tin' 

 bones of air, lighter (because warmer) than the air in which th' 

 bti'd is flying. The actual supporting power obtained in this way 

 can be easily shown to be utterly insignificant. It is simply the 

 difference between the weight of the air in the passages and t\v.v- 

 of an equal volume of the outer air. This is less, of course, tli:iii 

 the weight of a volume of air equal to the volume of the air- 

 passages, and much less than the weight of a i>ortion of air equal 

 in volume to the bird, which would corrospond to a very small 

 fraction of the biitl's actual weight, perhaps about one aOOch part. 

 The supjiort obtained in this way cannot be at the utmost more 

 than the 10,000th part of the bird's weight, and is not worth con- 

 sidering in dealing with the question of flight. — Fitful. 



[-1] — The Earth's Inclination. — In reply to " Moonstrnck's " 

 query, I should say that if the earth's axis was perpendicular to tlio 

 plane of the Ecliptic, the weather at the Polos would be much coMoi- 

 than a Polar Bumincr at present, because the rays of he:U would 

 fall very obliquely npon tho oai'th suiTOunding the Poles. At tlu- 

 Equator the heat would be greater than at present, because the sini 

 would daily appear to cross the zenith. — E. G. R. 



[1] — The Eakth's Inclination. — If the earth rotated on an uji- 

 right axis, there would bo perpetual spring or autumn all over t: .■ 

 earth ; but it must be remembered that spring and anfnmn at il • 

 equator are the hottest seasons of all, whilo at tho poles they nunn 

 ■a sun just skirting the horizon, so that tho coldest winter in 

 temperate regions would not be so cold as this so-called poku 



