JcLT 24, 1885.] 



♦ KNOWLEDGE ♦ 



when vessels had to depend on the wind for making a 

 passage." Yet, as a matter of fact, the advantages of 

 great-circle sailing are greater, nay much greater, for 

 sailing vessels than for steamships. Not only does it 

 often happen that the great-circle course would take a 

 ship into more favourable winds — as shown by Maury's 

 charts — than she would find on tlie rhumb course — but 

 even where no advantage of that sort is gained, and only 

 a saving of distance effected, this saving is of more im- 

 portance in the case of a sailing-vessel than in 

 that of a steamship, — because it represents a greater 

 saving of time and a yet greater relative diminution of 

 sea risks. And the gain is greatest of all when a ship 

 has to encounter adverse winds. For instance, if a steam- 

 ship starts fi-om the English Channel for New York on 

 a great-circle course, she may gain about half a day as 

 compared with her time on the Mercator's course. (I am 

 not here considering "the greyhounds of the sea," but 

 steam-vessels belonging to the carrying-trade.) To a 

 sailing-vessel with fair but light winds the saving would 

 be much greater, perhaps as much as a day and a-half or 

 two days. But supposing westerly winds to prevail 

 during the whole voyage, equally on the great-cu-cle and 

 on the Mercator's course, and that a sailing-vessel made 

 150 miles a day on the tack nearest to her course, then, 

 on the rhumb-line, she would traverse, (thus tacking) a 

 distance of 7,361 miles, and be 49 days on the voyage, 

 whereas on the great-circle course the distance traversed 

 in all her tacks would be 6,488 miles or 873 miles less, 

 while the time occupied by the journey would be but 

 43J[ days, — a saving of 4 days and 16 hours. (A sailing- 

 vessel as close to the wind, supposed directly adverse, as 

 she can, may actually on one or other tack be increasing 

 her distance from the port for which she is making.) 



3Reb(ctDS(* 



SOME BOOKS ON OUR TABLE. 

 Dictionary of National Bioyraphy. Edited by Leslie 

 Stephen. Vol. III. : Baker-Beadon. (London : Smith, 

 Elder, & Co. 1885.)— The third volume of Mr. Leslie 

 Stephen's admirable work will suffer nothing in com- 

 parison with anything heretofore published with a 

 cognate aim. Once more we find interspersed amongst 

 lives of men whose names are household words the 

 biographies of others whose mark in history has been so 

 faint or obscure as to render it certain that it would be 

 useless to look elsewhere for the story of their lives. 

 The Baliols are here, as are Balfour of Burleigh, Arch- 

 bishop Bancroft, Sir Joseph Banks, Barclay, Barham 

 (" Ingoldsby "), Barrow, and Bathurst, side by side with 

 Banting, the fat undertaker, and that " Dr. James 

 Barrj-," Inspector- General of the Army Medical 



partment, whom 

 readers will i 

 used to sit < 



! luir: 



my of 



iddle-aged 

 bald little Scotchm 

 ad swear, and who, i 



1, who 



death tw 



Inthebio-niiil.v .^f Willi:,... \\A\r (p. 7'.M, tl.r ;n,t lu.,v>s 

 speaks as tli.a.Vli hi^ .■l:.i'ii t" li:l^'' .H — .v,n ,1 tli.' 

 duplicity of Saturn's ring \v:is \\v-\ .IcnoHsli. .1 liy Mr. 

 Lynn in the Observatory fm- t >rl.ili. r, 1>Sl'. >„»„, 

 cuique, fvad we have not the sIIl.'!.!.^! ^^ i^li I" .l.t.Mcf 

 from Mr. Lynn's undoubted claim tn Ii.im' l.iiv.lv af-.sisud 

 in pricking Dr. Kitchener's bubble; but — n'lerely in 

 regard to the matter of chronology — the reader is re- 

 quested to consult pp. 294 and 295 of Vol. II. of 



Knowledge, which, of course, were published some days 

 before the periodical referred to. It is jretty evident, 

 however, from what source Miss Clerke derived her 

 materials. We note one omission in the volume before 

 us, which seems a little surprising, considering the 

 general extremely complete character of the work. 

 We refer to the fact that no mention is made of Sir 

 John Barton, the Comptroller of the Mint early in the 

 present centuiy, whose great mechanical genius and 

 power of invention certainly entitle him to a niche in 

 Mr. Leslie Stephen's Temple of Fame. He was, we 

 believe, the first man who practised the art of ruling 

 lines in excessive proximity, — an art which in our days 

 has culminated in the production of the so - called 

 " Nobert's lines.' Sir John Barton's iridescent buttons, 

 produced in this way, were described by Sir David 

 Brewster and Holtzajjffel. He devised, too, an ingenious 

 method of screw-cutting. 



Life, the Explanation of It. By W. SirCiWiCK, Major 

 R.E. (London : W. Thacker it Co. 1885.)— A cursory 

 perusal of this crazy book might impress the reader with 

 the idea that it was a clumsy attempt on the part of its 

 author to poke fun at the doctrine of Evolution. A 

 more deliberate study of it, however, has convinced us 

 that Major Sedgwick is really in earnest in advancing 

 his perfectly wild hypothesis of the genesis of life on our 

 globe. Whence, however, he obtained his science it is 

 hard indeed to conjecture. How any man educated at 

 the Royal Military Academy can gravely maiutain thfc 

 mechanical doctrines set forth in the opening chapters of 

 the work, passes our comprehension altogether. For 

 example, of the persistent action of gravity on a body 

 projected upwards (p. 11) our author seems to have the 

 haziest possible idea. Again: we learn on p. 16 that 

 the earth has a mere crust of solid rock, and is liquid or 

 molten inside. How the precession cf the equinoxes 

 happens under these circumstances we are not informed. 

 Furthermore: (p. 18) "Compulsive force" is driving 

 our system towards the constellation Hercules. This 

 ought (according to Sedgwick) to produce a " vast visible 

 source of light " in the direction of that constellation, 

 and the reason why we fail to perceive this is "that our 

 eyes .... are unable to appreciate the action of im- 

 pulses of compulsive force, unless they are retarded to a 

 sufficient extent by rcjailsive force." (!) Again, the expo- 

 sition of the d.ti i-iiiiiiiiiL: e.iuses of the earth's orbit, on 

 pp. 28-30, are iili....st «..iiliy of Zadkiel himself; while 

 on p. 32 it is gravely statr.l "that the moon is attached to 

 the earth, and the planets to the sun, "by columns, more 

 or less conical in form, of gaseous particles." It will 

 surprise no one to hear that the expositor of such 

 astronomy (?) as this persistently misspells the name of 

 Sir John Herschel throughout the volume. The re- 

 mainder of it we really will not weary the reader by 

 commenting upon. Haeckel's theory is as the utterance 

 almost of inspiration by the side of it. 



The Sextant. By Major H. Wilbekiokce Clarke, 

 Royal (late Bengal) Engineers. (London : W. H. Allen, 

 ct Co. 1885.)— Written by a man obviously most 

 tlior.iiiL'l.lv familiar with the instrument he describes, 

 iiimI ]i, r.s. .,■,;, Uy skilled in the method cf using it, this tiny 

 I'.i.ik i> ill ivrry respect excellent, and the very model of 

 \sli:ii Mi.li a work ought to be. Commencinir with a 

 ,lrsrri|iiin,, .if thc scstaut itself and il.r mrtl.o.ls ,.f 

 (r-iii.- ii, cmr author proceeds to fx|.lai'.i ln'w t., makr 

 its \avi.>us a.ljustments perfect, to t;ik<' ahuu.li - ImiI. at 

 sea, and on land by the aid of an artificial hori/.ou, .subse- 

 quently described, and to observe lunar distances. To 

 this succeeds the description of the artificial horizon just 



