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REMARKS ON MR. MARTIN'S CASE IN Nautical Magazine

FOR JULY, 1878. (See Diagram 2.) The wind is north. A is steering east, and sees a green light 3 points on her port bow, or bearing N.E. by E.=B. B is, of course, running anywhere between, say, S.W. # W., and S.E. by E.; probably there would not be very much difference between the speed of the two ships, assume it at 8} knots=1 knot in 7 minutes. A is supposed instantly to haul sharp up, say E.N.E., and with a speed of, say, 6 knots. A reference to the figure and tables will now show that (theoretically) if B is steering from S.W. by W. to S.W. \ W., A will cross her bows before B could arrive at the point marked 1 (but if B's speed were greater than A's, it could hardly be done at all); and that with B steering S.W. 1 W., collision must ensue at the danger point marked +. After this, or with B steering more to the southward, B would pass a-head of A; but I do not think she would see both red and green lights of A in time to be of any use, unless steering, say, from S.W. } S. to the southward. The danger point then (+) will be when B has A from } to 1 point on her bow, and this is not allowing any leeway to A; if, say, } point leeway were allowed, then A, 1 point on starboard tow of B, would be the collision bearing from B, or steering S.W.

Now to apply my proposal of double side-lights for all sailing vessels going free, as noticed in my letter published in your June number. Your correspondent in your January number (to which I referred in that letter), says, “What is felt to be wanted is that the lights should show the length, not the breadth of the ship,” and this is exactly what I propose to do. A further consideration suggests that the after lights might be carried, perhaps best at the quarter davits, as this would not only raise it above the bow lights, but throw it out from the side, by which it would better show clear of the clew of mainsail. In the position of danger as marked above, viz., A from 1 to 14 points on B's starboard bow, A, when heading east, would show both her red lights separate to B, and B's green lights would both be seen by A, but the after one a little over, and barely clear of the line of the lower one ; still, both would show, and, if not, then B must be so nearly end on that her red light must quickly show. From this I obtain that if

A sees the two green lights of B nearly one over another, she will best clear by keeping her course, or by keeping off a point ; but that if the green lights show distinctly separate, then keep a close luff, and put out her after lights, which would at once be an indication to B that she (A) is on a wind, and that on В it rests to keep clear. It may be suggested that the main braces would interfere with the after lights, but I think this might be obviated, even by taking the lights abaft the goose-neck.

A, steering east, sights green light of B, 3 points on port bow, distant 1} miles.

The wind is north.

B is steering, say, between S.W. & W. and S.E. by E. Speed, say, 8} knots for each.

A is supposed to haul sharp up at once, or E.N.E. Speed, say, 6 knots. Then A makes 1 knot in 10 minutes. B 1 knot in 7 minutes.

The points 1, 2, &c., C, D, &c., possible points of the contact (for illustration)

DIAGRAM 2.

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1 CABLE 2 "

MILE

MILE

..0

CROSSIMILE. TABLES OF DISTANCES TO BE RUN BY EACH TO POINTS OF CONTACT. A keeps her course East, 81 knots. A, close hauled, E.N.E., 6 knots = Cables. Mins. Cables. Mins.

1 cable a minute. AC ... 2 = 0 ... BC ... 13 = 9

Cables. Mins. AD ... 4 = 3 ... BD... 12 = 81 Al ... 5 = 5 ... B1 ... 10 = 7 AE ... 5 = 4 ... BE... 11 = 7 AF ... 7 = 5 ... BF... 10 = 7 A2 ... 71 = 71... B2 ... 8 = 51 AG ... 8 = 6 ... BG... 92= 65 A3 ... 9 = 9 +AU...9 = 64 +BH... 9=64+ A4 ...10 = 10 ... 5}= A). ...10 = 7 ...BI ... 8* = 6 A5 ...11 = 11

Cables. Mins.

[Oar space is very valuable, but we aro always ready to devote a page or two to our old correspondents at the Antipodes. That is, however, not the sole reason why we notice these letters. The problem solved is the most difficult one in the rule of the road, and it is one specially dealt with in Mr. Gray's book, and in this case there is the further question as to carrying two extra side-lights. We touch on the third point first, and in doing so we must say that we do not think the proposal for two of such side-lights is within the limits of practical application, unless they are carried in places and relative positions to be rigidly adhered to in every ship. To be of use, the after light must be placed at a fixed and known distance aft of the fore one and at a fixed and known distance above it. If this is not possible then the scheme is not practicable. If an additional light is wanted for sailing ships it should, we think, be supplied by one lanthorn that can be used for three purposes. Such a lantborn should have a green glass and a red glass, both moveable 50 as to be able to show red, white and green as wanted. The white light to be shown over the stern to warn overtaking ships, and the red glass to be used when the light is shown on the port side, to mean “ I am close-hauled on the port tack," the green glass to be used on the starboard side, and to mean “I am closehauled on the starboard tack.” We cannot but think that such a light as that used as an auxiliary light would be of great use, and would add as materially to the safety of sailing ships as the proposed voluntary whistle signals will add to the safety of steamships. As regards the other question raised by these problems we thank our correspondent, as his diagrams and his lucid explanations, apart from his views as to an additional side-light fixed on each side of the ship, are, we think, especially valuable to our young readers, and interesting to our elder ones.-Ed. N. M.]

TIDE TABLES FOR JANUARY, 1879.
Also Ports of Reference for the Constants in the next Table.

LONDON
BRIDGE.

| NORTH HULL. ISHIELDS

LEITH.

DEVON-
PORT.

WEEK

DAY.
MONTH
DAY.

WESTONI
DOVER. SUPER

"1 LIVER- | GREENIQUEENS KINGS- LONDON Oprar
MARE.

POOL. | OCK, TOWN | TOWN. DERRY.

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H. M.H. M. H. M.H. M. H. M.H. M. H. M. H. M.H. M.H. M H . M. H. M H . M. H. M. H. M.H. M.H. M.H. M.JH. M.H. M.H. M. H. M.H. M.H. M H M H . M.

7 221 7451 - Toul 9 7 9 8 8 11 8 30 10 47 11 18 4 25 4 4611 551 - 1 4 26 4 541 5 10 5 35 10 19 10 50 4 31 4 59 1 39 2 13 9 15 9 46
| 8 9 8 38 0 39 1 910 8 10 40 9 2 9 35 11 44 - 5 13 5 41 0 25 O 50 5 26 6 0 6 5 6 3 11 2111 56 5 29 5 59 2 471 3 18 10 19 10 54
9 11 9 49 1 89 2 9 11 13 11 47 10 8 10 410 17 0 50 6 11 6 44 1 29 2 6 37 7 13 7 9 7 43 - 0 2 6 29 7 1 3 48 4 17 11 29

24 10 59 2 40 3 13 -10 2011 13.11 45 1 25 2 0 7 2017 56 2 41 3 18 7 48 8 22 8 19 8 53 1 51 1 42 7 33 8 | 4 46 5 15 0 6 0 41
33 - 3 46 4 17 0 52 1 211 - 0 14 2 34 3 7 8 30 8 57 3 57 4 28 8 53 9 18 9 26 9 55 2 18 2 46 8 99 5 36 5 59 1 14 1 42
4 0 33 4 45 5 8 45 2 7 0 3 1 1 3 40 4 7 9 22 9 46 4 571 5 9 41 10 8 10 20 10 43 3 12 3 371 9 88 57 6 21 6 43 2 5 2 27
1 21 5 30 5 2 28 2 48 1 23 1 45 4 34 4 59 10 10 10 33 5 50 6 15 10 24 10 4111 611 29 4 1 4 24 10 17 10 37 7 5 7 27 2 49 3 10
6 14 6 85

2 20 5 22 5 44 10 56 11 19 6 39 7 211 511 2 11 52 - 4 46 5 8 10 57 11 17 7 49 8 10 3 81 3 52
6 56 7 14 82 46 3

3 6 6 5 6 25 11 41 -17 237 43 11 47 - 0 15 0 29 5 50 11 3711 578 29 8 471 4 13 4 33 8 3 231 7 37 7 571 4 28 4 48 3 25 3

3 416 45 7 5 0 30 25 8 28 8 211 0 8 0 29 0 571 1 171 6 10 6 30 - 0 17 9 5 9 28 4 53 8 16 8 161 8 36 5 91 5 30 4 4 4 4 21 7 25 7 450 47 i 9 8 40 8 59 49 1 9 1 87 1 571 6 50 7 11

58 9 41 10 11 5 6 8 5 8 25 1 53 9 18 9 37 1 29 1 49 2 171 2

311 7 51 1 20 42 10 2110 411 6 22 9 38 10 6 571 5 28 5 51 8 45 9 6 2 15 37 9 56 10 15 2 9 2

19 8 11 8 31 2 4 11 311 28 6 54 7 16
44 6 7 10 22 10 45 7 19 7 42 6 15 6 89 9 27 9 49 2 69 3 19 10 33 10 511 2 51 3

2 8 51 9 18 2 49 11 57 - 7 38 8
80 6 53 11 10 11 88 8 8 8 30 7 8 7 80 10 13 10 38 3 41 4/11 10/11 93 3 35 3 581 24 4 47 9 35 9 58 3 35 0 27 1 8 25 8 51
18 7 46 -
9 40 8 1 8 3411 411 33 4 28

- noon 4 26 4 57 12 5 40 10 25 10 4 81 5 S 1 37 2 16 9 21 9 56
16 8 50 O 43
58 9 11 9 51 -075 57 O 33 1 12 5 35 6 19 13 6 5211

5 37 6 14 2 55 3 34 10 36 11 19
10 18 1 54
- 10 31 11 12 0 45 1 25 6 35

54 2 39 7 3 7 47 7 33 8 14 0 20 6 52 7 32 4 55 11 37 3 12 3 52 0 - 2 6 2 47 8

8 271 9 1 8 69 9 30 1 48 2 27 8 12 48 5 17 5 451 047) 1 23 0 16 4 271 4 58 1 0 53 3 28 4 4 9 12 9 43 4

9 39 10 C10 10 10 40 3 2 3 34 9 23 9

23 9 54 6 13 6 401

1640 1 571 2 25 21 0 50 1 18 5 261 5 52

1 471 4 36 5 8 10 11 10 37 5

10 25 10 411 811 54 4 2 4 210 20 10 41 7 7 7 51 3 14
1 451 2

26 5 48 11 211 25 6 11 11 11 38 11 58 - 4 51 5 211 29 7 54 8 86 3 58
2 29 2 1 7 1 7

6 81|11 47 -17 11 54 - 0 21 0 42 5 84 5 42 - 8 84 8 18 4 37 3 9 3 27 7 42 8 0

7 9 0 8 0 2

251 8

8 6 8 23 0 14 0 33 1 2 1 21 6 13 6 31 0 1 0 20 9 8 9 24 4 051 5
8 8 17 8 34 5
26 4 4 4
7 41 0 47 1 0 8 39 8 54

88 0 50 9 89
878 50 9 6 5
0 4 38 4 57 8 12 1 23 1 40 9 9 9 24 1 87 2 11 2

7 86 1
5 99 22 9 886

6 84) 5
26 8 40 1 57 2 14 9 89 9 52 1 2 0 2 48 2

8 7 1
24 5 89 9 54 10 10 6

6 8 8 53 9 0 2 80 2 4610 610 18 2 40 8 14 3 29 8 22 8 87 2 20 2 87 11 1611 887 6
54 6 11 8 10 407
6 41 9 21 9 86 3 8 8 20 10 31 10 44 8 18 3 45

2 9 8 2 3 18 - 0 1 7 39 6 29 6 4 11 6 11 2018 0 7 21 9 64 10 14 8 37 8 5411 011 20 29 9 4 4 19

51 0 24 0 51 8 15 8 7 9 7 8211 1910 8811 8 4 14 4 89 11 47 - 12! 4 42 4 68

49 1 23 2 1 9 6 9 89

20

106

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TIDAL CONSTANTS FOR VARIOUS BRITISH, IRISH, AND EUROPEAN PORTS. By applying the Tidal Constant of the place, according to its sign ( + add, – gub.), to the time of high water on the given day at the port of reference, you hare the time of high water at the place sought.

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