188 



KNOWLEDGE 



[Dkc. 30, 1»81. 



Sooipty of London. In tiio paper to which Mr. MoUoy roforn, " An 

 Account of sonio E.<poriniontH to Moimure tho Velocity of Electricity 

 and thr Duration of Electric Li^jht." Whoatstone f^ves nn account 

 of exporimoiita made on the duration of tho oloctric spark, iia pro- 

 duced in the laboratory, and towards tho conclusion of his paper he 

 states that " tho light of electricity in a state of high tension has a 

 less duration than tho millionth part of a second." 



If " (i. S. M." (quorj- 07) could gee a rainbow under perfect con- 

 ditions, it would appear not semicircular, but circular. If, for 

 example, ho were up in a balloon, at a great height, with tho sun 

 overhead, and a rain-showor beneath, he would Boe a circular 

 rainbow below, probably with tho shadow of his car and its occu- 

 pants fair in tho centre. A rainbow being formed by those rain- 

 drops which aro placed at a particular angle with regard to a lino 

 drawn from tho sun tlurough tho hoad of tho observer, it is appa- 

 rent that as our balloon descended towards tho earth tho coloured 

 ring woulil descend also, until finally it impinged on tho earth's 

 surface. Upon going lower still, tho continuity of tho ring would 

 be broken, tho earth having taken tho place of some of tho rain- 

 drops, and, probably by the time the obBerver had reached the 

 ground, he would be only ablo to see a semicircular rainbow. 



Wm. Ackuovu. 



COMETS' TAILS. 



[162]— In reply to the query by F. C. S., p. 119, Mr. G. M. 

 Scabrook, Temple Observatory, Rugby, writing to Nalvre, says : — 

 "The comet (b. 18S1) was examined spectroscopically here last 

 night. The nucleus gave a bright, continuous spectrum, while the 

 coma and brighter portions of the tail gave the throe least refrangible 

 hydrocarbon bands superposed on a faint continuous spectrum. On 

 moving the slit of the spectroscope towards the fainter part of the 

 tail the bands died out, leaviii;:: a faint continuous spectrum, which, 

 again, gradually faded away us the end of the tail was approached. 

 I have not measured the position of the bauds, but they are sensibly 

 the same as those from an alcohol flame." 



Mr. Percy Smith, of tho same Observatory, on July 1, writes : — 

 "On the 27th (June), the bright jet extending from the nucleus 

 was very plain, and gave tho hydrocarbon spectrum very distinctly. 

 No bands were seen in the tail, but only in the immediate proximity 

 of tho nucleus." 



M. Wolf, in a paper read to the Paris Academy on July 11 (in 

 regard to the same comet) says : " . . . " When the slit of the 

 spectroscope is passed over the comot, starting from the head, one 

 finds the three bands all round tho nucleus at nearly the same 

 distance from all the sides. They disapjjear in the tail properly so- 

 called, the very pale spectrum of which seems to be continuous. 

 Thus only the nebulosity surrounding tho nucleus contains incan- 

 descent gases. The light of the tail comes to ns from a pulvoralent 

 matter luminous or simply illuminated. Snch are the data of 

 spectroscopy." ..\. T. C. 



AN INSTANCE OF PRESsUEE. 



[163]— Tho readers of KNonxKDGKhave, doubtless, been interested 

 in tlie scientific controver.sj- on the subject of toads being enabled to 

 live, enclosed by blocks of solid matter ; probably the following fact 

 will be unknovra to many of them, and may afford additional proof 

 of the frog's vital tenacity : — 



A few years ago an experiment was made in the Arsenal at Wool- 

 wich, the jiarticulars of which were published by the well-known 

 Mr. Tegetmeior, of tho Field. A frog was subjected to the enor- 

 mous pressure of three tons to the square inch, for a period of 

 thirty-six hours. At the end of the experiment the frog appeared 

 prostrate, but recovered a perfectly normal condition in a few 

 hours, and as a reward for his severe tost, was taken back to his 

 native marshes. R. 0. Prasee. 



A GEOQIUPHY of the almost unknown kingdom of Corea has been 

 compiled by a member of the suite of the Japanese envoy to that 

 country. Several valuable papers, containing accounts of travels in 

 Corea, have been read before the Oeograpliical Society of Tokio, and 

 have appeared in its transactions. As they arc written in Japanese, 

 they are unfortunately all but inaccessible to European geographers. 

 — Frank Leslie's Mayaziiif. 



TiiK French Minister of Commerce has just issued a notice 

 regarding tho inspection of salted pork imported from abroad. 

 Inspector.s are to bo appointed at the different ports to which tho 

 entry of this commodity will be confined. A course of lectures on 

 the .subjix't of micrography is to bo instituted at tho School of Phar- 

 macy for the preparation of tho experts who will be required for 

 these posts. These measures foreshadow the eventual raising of tho 

 embargo on American pork. 



(©utrifsf. 



[ 130J — Known Langl'ages. — 1 shall bo glad if you, or any of the 

 readers of Knowlkuge, can tell me the number of known languogcji 

 spoken at the present day. — J. A. L. K. 



[131] — Ckkatios. — Will any correspondent versed in this sabjoct 

 give his views aa to what aro tho proofs of man havi[>gexisle<l more 

 than six thousand years ?^U. I. P. [R. I. P. should read, amongnt 

 ■ither works, " Quatrofagcs on Man," in tho International Scrieji, 

 published by Kegan Paul & Co., London. Price 5s. — Ed.J 



[132] — FiJKOi. — I shall be glad to have any information respect- 

 ing the nature of fungi and trutBcs ; h»w they are produced, and 

 what their place is in tho vegetable kingdom. — Ionotus. 



[133] — Would you kindly inform mo if you know of any works, 

 articles in magazines, or anything whatever by the Rev. W. H. 

 Bollinger, P.R.S. ?— Quekist.' 



[134] — TtiK Stars in Northern and SocrnEBN Latitudes.—^ 

 Would you oblige a boy by explaining the reason why we in northern ' 

 latitudes do not see the whole of the southern constcllationB, as 

 people in southern latitudes see all our northern constellations 7 

 Vide page 12 of " Easy Star Lessons." You state the fact, but do 

 not give the reason. — Qoisquis. — [At the North Pole, the pole 

 would be overhead, and tho heavens turning around on upright or 

 vertical axis, we should see only one half the star sphere, even if . 

 wc watched through twenty-four hours of an arctic winter's day. 

 (really night). At tho equator, the poles being on the horizon, we, 

 should see tho whole star sphere, turning as it does round a hori- 

 zontal axis, in tho twelve hours of an oquatorial night. In inter- 

 mediate positions, more or less of the star-sphere would be seen the 

 nearer the station to the equator. You must not confound latitudes 

 south of ours with southern latitudes. — Ed.] 



[135]— CoEAP Telescope. — I am wishful to have a cheap tele- 

 scope, such as would answer a beginner ; say a 2i" or 3" object- 

 lens. Would any reader give me a few hints as to construction, 

 what would be probable cost, including tube, ic. ? — R. I. P. 



[136] — Sunlight on Fikes. — Does bright sunlight interfere with 

 ordinary combustion ? If, as I believe, it does, I should be glad to 

 have a scientific explanation of the fact. As evidence, let me qnota 

 tho housemaid, who says she cannot get her firo to bum if the sun 

 is shining upon it. And the smoker, who says that he cannot keep 

 his cigar alight under the same circumstances. — N. 



[137] — Humble Bees. — What success has attended the attempt 

 to introduce humble bees (Bomhus terrcstris) into New Zealand, to' 

 fertilise the clover there ? The first attempt was unsuccessful, but 

 I have been unable to learn the fate of the second attempt. — 

 Thomas Chandler. 



[138] — The Gyroscope. — What particular laws of motion are 

 illustrated by the gjroscope ? Does it thi-ow any light upon plane- 

 i;arj motions ? And what ? Of what motions is the instrument 

 capable, and can they be popularly explained ? Is there any simple 

 treatise on the subject ? Can you give some easy papers upon it in 

 Knowledge ? — T. W. F. [Newton considered the movements of a 

 rotating body under gravity among tho most difficult problems which 

 mathematics can deal with. Wo have tried elsewhere to make 

 this difficult matter clear, and may try again soon in these pages. 

 —Ed.] 



[139] — TEMrER.\TUHE OK Interstellab Sp.\ce. — What is the sap- 

 posed temperature of interstellar space, and how has it been' 

 ascertained ? — E. C. R. 



[110] — Ice. — Does the volume of ice vary as other solids do' 

 with variation of temperature ? — E. C. R. 



[141] — Time of Glacial Epoch. — Is Dr. Croll's theory of ther 

 time at which the ice age existed in Britain probably correct ? Aza 

 there other theories on the same subject ? — E. C. R. • 



[142] — The Great Beak.— Will some reader of KnowlidsM 

 inform mo if it is possible to see the Great Bear 174° south of the 

 equator ? I read in a book (and tho author ought to have known); 

 that it is so, but it seems hardly credible. M'ould some one 6tat» 

 how far south it may bo seen ? — Marian. [Any star of the Gr eat 

 Bear can be seen just as many degrees south of the equator as thai) 

 star is distant from tho polo of tho heavens. — Ed.] 



The biggest thing yet in tho way of plaster casts is the cast of a 

 whale, taken at Provincetown by Mr. Palmer, modeller for the 

 Smithsonian, at Washington. A papier-mache fac-simile is to bai 

 moulded from tho cast, tho entii'e skeleton of tho samo whale isUfJ 

 be inserted, and the monster will be suspended in the museum, 

 show tho arrangement of the skeleton, one aide of the whalo ' 

 be loft open. 



