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"TAE MARINE. REVIEW : vy ll nee 77 Ne = II-I 3. To If a vessel logs 137 miles in 1134 hours, what number of miles is she logging per bour? Ans. 11 31-47, about 11 2-3 miles. 137 + 1134 = 137-1 X 4-47 = 548-47 = 11 31-47. If it takes your boat 34 of an hour to run 734 miles, what rate of speed are you making per hour? Ans. io 1-3 miles per hour; found thus, 7¥i = Va, OF 31 % 4 --- = 31-3 = 10 1-3 miles. 4° oR Proof: -%4 of {10 1-3) 31-3 (4X 31-3 = 31-12) -- 27-12 miles in 34 of an hour; 2 7-12' X 3, or 31-12 X. 3-1'= 93-12 = 73% miles. The explanation is as follows: If she makes 10 1-3 miles in one hour, in one-fourth of an hour she will make % of 10 1-3 which is 2 7-12 miles, and in 34 of an hour she will make 3 times 2 7-12 miles, which is 734 miles. If it takes your boat 21%4 minutes to run 334 miles, how fast is she running per hour? Ans. 10 20-43 miles per hour, found thus, 21% + 334, or Dee 43. %5.4 --_------ = 86-15:= 5 II-15 minutes to make one mile. Q(X 16 1% 60 minutes in one hour, therefore, 60 + 5 11-15 is 60 X 15-86 = 900-86 = 10 20-43 miles she would make in one hour. If your boat makes 1114 miles an hour how long will it take to run from Chicago to Pt. Betsey, the distance being 203 statute miles? Ans. 18 2-45 hours, or 18 hours and 3 minutes, nearly. ; It takes your boat 9 3-5 hours to run 983% miles, how far will she run in one hour? Ans. 10 95-384 miles. Divide 7% by 3%. Ans. I 1-6. - THE SUBJECT OF DEVIATION. Editor Question Dept.: I either. don't understand Mr. Long. or else I am mixed up in my ideas of deviation. In his ar- ticle under date of April 5, headed "What Every Master Should Know," near the bottom of the second column he makes the statement: "Dev. taking no part in the problem, because it remains the same for that heading of -the vessel whether in the Sault river or on Lake Superior, providing, however, that the change of latitude is not too great." Now, where I don't agree with Mr. Long is where he says that Dev. remains the same'on that heading whether on the Sault river or Lake Superior--the Dev. is hardly ever the same in the. same place, different conditions such as different kinds of _ cargo, different trim of the vessel, with water ballast in or without water ballast, all of the different conditions tend to change the Dev. either to increase or decrease it. On my first trip up Lake Superior this spring, I found on the course from Eagle Harbor to Devil Island that my compass had 7% of a point easterly Dev. after allowing Var. This result I got by using the pelorus, On my return trip I found 5% point east- erly Dev. Then I may get a cargo of iron ore which has a greater or less percentage of iron in it that will again make a difference in the Dev. I notice this time up on Lake Huron that I had less Dev. than last trip up between Ft. Gratiot and Sanilac, heading N. %4 E. by compass pelorus showed N. Mag. This time there was no Def. N. and compass was N. Mag. under practically the same conditions, no wind, water ballast out of Nos. 1 and 2 tanks. Now, if I have made a mistake I want to know where it is. I use the pelorus constantly and so far have had good success with it. I don't think there-is a place in the world where piloting is any nearer a science than on the great lakes, where conditions are so varied and changeable. A thorough knowledge of Dey. and its causes is certainly very essential to the lake masters, but when it gets thick like some of the days we had last year, and the master don't know what his Dev. is--possibly has not had a chance to find out--there is where he is "up against it" strong. Take a boat lying idle all winter, say near a big pile of iron ore, or alongside of sev- eral other boats for over three months. Her compass can't be in very good shape in the spring, and it will take several trips for that compass to get its bearings. The Dey. will be constantly changing. I know this by experience. I would like to have Mr. Long tell me whether I am right or where my mistake, if any, is. I am very much interested in his articles and am absorbing all I can get of them, and they are to be a great help to us all. : E. L. Sawyer, Master Steamer Griffin. EFFICIENCY OF SUBMARINE SIGNALS. The Submarine Signal Co., 247 Atlantic avenue, Boston, exhibits the following letter sent to Vernon H. Brown, agent of the Cunard Line, by Capt, James B. Watt, of the steamer Lucania: "Re submarine signal--I beg to report as follows: "We had hazy weather with showers of misty rain off the Nantucket shoals and we would have failed to locate - the light vessel but for the aid of the submarine signal bell. We ,heard it 8% miles distant whilst steaming full! speed, 22 knots, on the starboard bow, or side, thus . -- -, two strokes, a short interval, then one stroke. The ship's course was altered to the northward just so that the sound of the bell could not be heard on the port side. We made the light vessel one point on the starboard bow and passed it one-third of a mile off which enabled us to obtain a good departure. The sound of the bell was mus- ical and distinctly audible and could not be mistaken for any other sound. To my mind this is a very satisfac- tory experience as it brings home to one the practica- bility of the system." The following letter was also submitted by Capt. C. Kaempff, of the steamer Deutschland: "Left Cuxhaven on Jan. 18, 4.20 P. M. The wind was S. W., strength 4-6, the weather rainy and thick. The observation was begun at the Elbe V. The first evidence of a sound was heard one knot inside of the H lightship and at a distance of 514 knots. At first it was heard good and clear on the port side, but it could no longer be heard when the lightship I was dead ahead. With the rudder to starboard the ship was turned more to port, about four degrees, when almost immediately the four strokes of the bell were heard clearly again. At first the sound was without any ring, but on approaching nearer, the sound became good and full. It could still be heard until about three knots astern, one point onthe port. In the opinion of all, the former perceptible ship's noises had disap- peared and only the rush of the water was noticeable. Unfortunately, on account of the difficulty of maneuver- ing as a result of the thick weather and the great amount of traffic at the time in the neighborhood of the light- ship, the apparatus on the starboard side could not be tested. The bell on the Weser lightship could not be heard when passing, at about 6.42 P. M., three to five knots distant." 'B. L. Dimon and J. R. Rowland, two officials of the Joy line, have been appointed vice president and general manager and traffic manager respectively of the Brunswick Steamship 'line, which is to be operated between Brunswick, Ga., New York, and Boston, as soon as its vessels are completed. '