KNOWLEDGE 



193 



^1^^ ^N ILLUSTRATED ' ^J^ 



T>^ MAGAZINE OF SCIENCE ^ 



L PLAINDfWORDED-EXACTLYDESCRlBED : 



LONDON. FllIBAY, SEFIEMBJOL i, lbb5. 



Contents of No 201 



Finding the Way 



>-Th6 Philosophy o 

 Jreasy Dncke-Sta 

 rkable Sky — Evol 



FINDING THE WAY AT SEA. 

 By Richard A. Proctor. 



(Continued from p. 177.) 



EVERYONE v/ho makes a long sea-voyage must liave 

 noted the importance attached to noon observa- 

 tions ; and many are misled into the supposition that 

 these observations are directly intended for the determi- 

 nation of the longitude (or, which is the same thing in 

 effect, for determining true ship-time). This, how- 

 ever, is a mistake. The latitude riiu \n- ih-trriniiK-a 

 at noon, as we have seen. A rougli njijirdxiniutidii 

 to the local time can be obtained, ami is cdmrnniily 

 obtained, by noting when the sun begins to dip 

 after reaching the highest part of his course above the 

 horizon. But this is necessarilv "iih/ a rough apprnxi- 

 mation, nnd quite uusuited fnr "dctrrminiiic,^ the ship's 

 longituJr. Fnrtlir sun's ,'lrv;itin,i .■l,;u,._:,^s very .slowly 



t,n;i lirnni. I;,!- Irss fro,,, ;, >l,ii,. v.u]>m :, frw minutes of 

 true noon. A deteni.iuai i.n, ..f t imr efteeted in this way, 

 serves very well fur thr sliip's ■■watches," and accord- 

 ingly when the sun, s.. .il-si r\v,l, begins to dip, they 

 strike " eight bells " and " uiakt' i( noon." But it would 

 be a serious matter foi- the crew if that was made the 

 noon for working the ship's place ; for an error of many 

 miles would be inevitable. 



The following passage from "Foul Play," illustrates 

 the way in which mistakes have arisen on this point. 

 The hero, who being a clergyman and a university man 

 is of course a master of every branch of science, is about 

 to distinguish himself before the heroine by working 

 out the position of the ship Proserpine, whose captain is 

 senselessly drunk. After ten days' murky weather "the 

 sky suddenly cleared, and a rare opportunity occurred to 

 take an observation. Hazel suggested to "Wylie, the 

 mate, the propriety of taking advantage of the moment, 

 as the fog bank out of which they had just emerged 

 would soon envelop them again, and they had not more 

 tlian an h(mr or so of such observation available. The 

 man gave a shuffling answer. So Hazel sought the 



1 I 1 I I I He found him in bed He was 



I hclf hy the instrument'- Thcs 



I I oked round fo: the chronomettis 



I \ ' 1 111 till 11 ( i^t s He carried the 



t 1 1 . \ itl, l„ok of tables, and 



1 1 1 it which "Wylu, 



II I I 1 nil 1 istoni'.hment " ( .s 

 ell lit uu^ht; 



"'Now, "Mr '\\ylie, I y 



t the kej of the chronomttii 



'Htrt is 1 chronometer. Mi Hazel,' said Helen, vei \ 



ncciith if th,t IS dl yn^^ in " 



1 iim 1 til it a ship's clock iv 

 mad. t 1 1 il, 1.. I '. X . t tiiui , that he did not 

 lequiio Uic tmiL Lf tht s| t uhciL thtj weie, but Green 

 V, ich time. He took the v, atch, however. It was a largi 

 one for a lady to carry, but it was one of Frodsham's 

 masterpieces. 



"'■Why. ^ri:-- rtrli •-*,.,-,.' CI,-,! he, 'this watch must be 

 two Lmui,-, -1,,,, li , ' !Mi o'clock; it is now nearly 

 midil:i\. Ail, i , I I I with a smile, 'yon have 



wouii'l it r. jiiIm '. I -. <i \, hut yon have forgotten to 



srI it ilaiK. lii.l'.a. v^ii inav he 'ri-ht ; it would be a 

 „.,.|r., trnlllilr, silH'c'ur rlla,.-- Mir iMl-illule hourlv. 



W'.ll, Ift 11^ sujiiiosi^ tliat iliis NMiti'h sl,ov,s the exact 

 time at Syani-y, as 1 j iTsui.i,' it .l.,rs: I can work the 

 ship's reckoning from tliat nn riilian. instead of that of 

 Greenwich.' And he k i ali^ut (l.iing it. Wylie, after 

 some angry words with lla/.i !. l'iii,L;s the chronometers 

 and the charts. Hazel ' veiilied Mi.■^s RoUeston's chro- 

 nometer, and allowing for difference of time, found it to 

 be accurate. He returned it to her, and proceeded to 

 work on the chart. The men looked on ; so did Wylie. 

 After a few moments, Hazel read as follows: West longi- 

 tude 146° 53' 18", Soutli latifudr ;i."i' 21'. The island of 

 Opara*andthe Four Crouns .listaiit 420 miles on the 

 N.N.E.' and so on. And, of course, 'Miss RoUestoii 

 tixid lier large soft eyes on the young clergyman with 

 the uiiilisLiuised admiration a woman is apt to feel for 

 what slir does not understand." 



The scene here described corresponds pretty closely, I 

 hnve little doubt, with one actnrdly witnessed by the 

 novelist, except only that the captr.in or chief officer 

 made the observations, and that either there had not 

 been trii days' iiiurl.y w.Mthrr or olsr tliat in (1„. [..rr- 



of t 



I lir, 



h\ 



Sydney time would be about 2 hours slow, but about i hours slow 

 .n longitude 147° west. 



