DISCUSSION ON TWO PRECEDING PAPERS. 131 



her oscillator to the other ship her speed and her course, and they can interchange that in- 

 formation instantly by the Morse system, that is about all they want to know ; that is to say, 

 it would be at least a very great factor in saving these ships from collision, for the reason 

 which I advanced in my first talk, namely, that this does not require any technical knowl- 

 edge, but simply requires a man who is a good observer. He should not be in charge of the 

 ship if he were not, because, after all, the use of this apparatus is only intended as a means of 

 intensifying his ability as a navigator and enabling him to concentrate his attention on the 

 bridge. 



Mr. Goulder : — In connection with the definiteness of these sound signals. Judge Addi- 

 son Brown, the former District Judge in New York, who was a leader, if not without a 

 peer in admiralty judgment, in the case of the S. S. Lepanto, 21 Fed. Rep., after reviewing 

 the whole subject, taking in "Tyndall on Sound" and all that was known, held that a mistake 

 of five points in the supposed direction of a whistle sound could not be called a fault. He 

 made the range of five points. 



Commander Sawyer: — I have been asked to explain more particularly how the distance 

 between ships in a fog is obtained. 



By reference to Fig. 11, Plate 50, this distance is read off directly upon the scaled paper 

 from the length of the Hnes, the paper being marked for each mile and one-tenth of a mile. 

 All the operator on watch has to do is to press his key when a wireless letter is received, 

 and release the key when the corresponding under-water signal is heard. The wireless letter 

 travels 180,000 miles in a second and the under-water signal three-fourths of a mile in the 

 same time. In the U. S. S. Arkansas-Utah tests the time between the wireless signal and the 

 submarine signal would have been 13 seconds or nearly a quarter of a minute at the longest 

 ranges reached — about the time you would ordinarily count thirty. An average telegrapher 

 or signalman uses one-tenth second for a dot, and an unskilled observer ought to be able to 

 work in twice that time which would measure the distance between the ships to 300 yards, 

 or one to two ships' lengths. This is much closer than necessary for navigation purposes sc 

 far as fog is concerned. 



In regard to the question of direction, which Mr. Millet suggests may be obtained by the 

 use of submarine signals alone, it does not seem possible that this will ever be satisfactory 

 by itself for fog navigation. 



Suppose that a submarine signal is heard on one side only. The bearing is unknown, 

 but only the fact that the other vessel bears somewhere between 16 points of the compass. 

 If the attempt is made to locate the bearing as in the case of a submarine bell, the two ves- 

 sels would have to change course and endeavor to head for each other. As both vessels are 

 moving and turning, it would be much more difficult, if not impossible, to determine the ap- 

 proximate bearing. The distance between the vessels would be unknown, and it would seem 

 that an effort to utilize this method would increase the danger of collision as compared with 

 vessels not so equipped. 



It must be remembered that vessels may collide on every bearing but cannot collide 

 at every distance. 



A practical seaman is never afraid of collision if his vessel never gets within a mile of 

 another, and with that assurance, all he requires is, first, to know whether the vessels are 



