404 



NA rURE 



\J\Iarch'Z, 18^7 



limits of safe prophecy when he declared to the British 

 Association in Glasgow that the old system of deep-sea 

 sounding by hemp rope had done its last work on board 

 the Challeng^er. 



In proceeding to speak of astronomical navigation the 

 author begins by giving a series of definitions which 

 differ from those commonly given, by being based on no 

 assumption as to the figure of the earth, so that they 

 " designate in each case the thing found when the element 

 in question is determined by actual observation." Thus 

 the latitude of a place is defined as the altitude there of 

 the celestial pole. After a flying shot at the British 

 Statute mile, whose existence " is an evil of not incon- 

 siderable moment to the British nation," he goes on to 

 describe the various means of deducing a ship's place 

 from observations of the heavenly bodies, giving the 

 place of honour to Sumner's method, of the merits of 

 which we had recent occasion to speak (Nature, 

 vol. xiv, p. 346). 



To communicate information from ship to ship by 

 signals is an object of first importance to the sailor. By 

 day, in clear weather and with skilful men, the system of 

 flag and semaphore signals at present in use in the navy 

 is very complete and effective. By night, in clear weather, 

 Capt. Colomb's method of flashing signals has been suc- 

 cessfully used in the British navy for nearly twenty years, 

 but its adoption has not been nearly so general as properly 

 to meet the requirements of the case. On this point Sir 

 W. Thomson says: — 



" The essential characteristic of Capt. Colomb's method, 

 on which its great success has depended, consists in the 

 adoption of the Morse system of telegraphing by rapid 

 succession of shorts and longs, * dots ' and ' dashes,' as 

 they are called ; and, I believe, its success would have 

 been still greater, certainly its practice would have been 

 by the present time much more familiar to every officer 

 and man in the service than it is now, had not only the 

 general principle of the Morse system but the actual 

 Morse alphabet for letters and numerals been adopted by 

 Capt. Colomb. A modification of Capt. Colomb's sys- 

 tem, which many practical trials has convinced me is a 

 great improvement, consists in the substitution of short 

 and long eclipses for short and long flashes. In the sys- 

 tem of short and long eclipses, the signal lamp is allowed 

 to show its light uninterruptedly until the signal com- 

 mences. Then groups of long and short eclipses are pro- 

 duced by a movable screen, worked by the sender of the 

 message, and read off as letters, numerals, or code signals 

 by the receiver or receivers. . . . Whenever the light of 

 a lamp suffices, the eclipse method is decidedly surer, 

 particularly at quick speeds of working, than the flash 

 method, and it has besides the great advantage of show- 

 ing the receivers exactly where to look for the signals 

 when they come, by keeping the signal lamp always in 

 view in the intervals between signals, instead of keeping 

 it eclipsed in the intervals as in Colomb's method." 



Is it too much to hope that before very long a know^ 

 ledge of the Morse alphabet may form part of the ele- 

 mentary education of every boy and girl in the kingdom ? 

 Only then can the public awaken to a sense of the many 

 uses to which such a knowledge could be put. 



But there is a third set of conditions where signalling 

 is more necessary as well as more difficult than in either 

 of the other two. In fogs, by day or night, visible signals 

 have to be given up as useless, and audible ones take their 

 place. We may utilise Colomb's code or the Morse al- 

 phabet by giving short and long blasts on a steam whistle 

 or fog-horn. 



■** But here again a very great improvement is to be 

 made. Use instead of the distinction between short and 

 long the distinction between sounds of two different 

 pitches, the higher for the ' dot,' the lower for the ' dash.' 

 Whether in the steam whistle or the fog-horn a very 

 sharp limitation of the duration of the signal is scarcely 



attainable. There is, in fact, an indecision in the begin- 

 ning and end of the sound, which renders quick and sure 

 Morse signalling by longs and shorts impracticable, and 

 entails a painful slowness, and a want of perfect sureness, 

 especially when the sound is barely audible. Two fog- 

 horns or two steam- whistles, tuned to two different notes, 

 or when the distance is not too great, two notes of a bugle 

 or cornet may be used to telegraph words and sentences 

 with admirable smartness and sureness. Five words a 

 minute are easily attainable. This method has the great 

 advantage that, if the sounds can be heard at all, the dis- 

 tinction between the higher and the lower, or, as we may 

 say for brevity, ' acute ' and ' grave,' is unmistakable : 

 whereas the distinction between long and short blasts is 

 lost, or becomes uncertain, long before the sound is 

 inaudible." 



To produce powerful blasts of sound differing from 

 each other in pitch the Americans have devised an instrur 

 ment which is much more effective than the fog-horn or 

 steam-whistle. By the irony of fate sirens are now 

 enlisted in the service of humanity, and no longer lure 

 sailors to destruction. The reform in their morals, how- 

 ever, has been fatal to their romantic charm, for now they 

 are " driven at a uniform rate by clockwork, and the blast 

 is supplied from a steam boiler." But is the change to 

 be regretted when we hear that : — 



" Short and long blasts of the siren might be advan- 

 tageously substituted for short and long blasts of the 

 steam whistle, but inuch 7nore advatita^^eoiisly short blasts 

 of two sirens on the same shaft, or on two shafts geared 

 together, sounding different notes, acute note for the short, 

 grave note for the long. The rapidity and the ready dis- 

 tinctiveness of character of the two notes will then be 

 such that every officer and man will habitually recognise 

 evolutional signals and signals for course and speed, just 

 as in skirmishing every officer and private knows the 

 bugle calls ; and the signal-book will be no more needed 

 on the bridge of a ship of war than on the saddle of a 

 field officer. When the admiral desires to alter speed or 

 course for the fleet, his order will be given to the whole 

 fleet simultaneously, and very nearly as fast as he can 

 speak it to his flag captain, and then instantly (without 

 waiting to open signal-books) the other ships will, one 

 after another in order, each in replying give the ' under- 

 stand,' repeat the numbers expressing course and speed, 

 and make her pennant. In as many quarter-minutes as 

 there are ships under his command, the order will have 

 been thus securely acknowledged by every one of them, 

 and the admiral will sound his signal announcing that the 

 order commences to take effect. Nothing short of this 

 in quickness and sureness of ordering the mo^^ements of 

 a fleet ought for a moment to be thought of as tolerable, 

 when it is certain (as it assuredly is) that so much is 

 readily attainable." 



We have quoted this part of the lecture at considerable 

 length, for we have a strong conviction of its high prac- 

 tical value. , The collision between the Monarch and the 

 Raleigh in Besika Bay, which has happened since the lec- 

 ture was published, serves to point Sir W. Thomson's moral. 

 We are told that when the squadron was in three lines 

 steaming at about five knots an hour, a signal was made to 

 alter the course, which " from seme unexplained cause " 

 was misunderstood by two of the ships — the Triumph and 

 the Invindble. This brought the latter across the bows 

 of the Monarchy which then stopped and reversed engines, 

 but the Raleigh, astern of the Monarch, kept on her 

 course, the result being a collision, which was fortunately 

 much less serious in its consequences than the costly 

 Vanguard experiment, of which this one bid fair to be a 

 repetition. That the signal was misunderstood, not by all 

 the ships, and yet by two of them, seems to. prove that 

 much blame cannot be attached either to those who made 

 it, or to those who read it ; it is, in fact, the system that is 

 at fault. 



