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easterly. Then the range of mag- netic north would have a true bearing of N by E, since the true directions corresponding to the magnetic direc- tions are to the right. The rule says to find the true bearing from the mag- netic or correct magnetic bearing, al- low easterly variation to the right of the magnetic or correct magnetic bearing, and westerly to the left. Now, one point to the right of north mag- netic gives N by E true. From true to magnetic or correct magnetic, east- erly variation to the' left, and west- erly to the right; hence the true bearing NN by FE, Var. 1.pt. Ely... mag netic or correct magnetic bearing north--1 point to the left of N by E. To prove again that there is no dif- ference between magnetic and _ cor- rect magnetic when the variation has been allowed for--taken out. The true bearing of a range is SE true. To start with there is neither variation nor deviation. Head your vessel north (true) by compass and- lay across the range so that when you are in line with the range your compass reads SE. Now, imagine your boat to be perfectly stationary heading north .by 'compass. and the ©range bearing SE by the same compass. While in this position imagine 'your compass to be affected by one point of easterly variation; that is, the card has swung one point to the right of its former position. Then your boat will be heading N by W by compass, and the bearing of the range is SE true with one point of easterly varia- tion the correct magnetic bearing would be SE by E, and to head by compass in order to bring this range SE by E, you would have to head N by W, thus allowing for the variation. When the compass swung for the amount of the variation it corrected itself, on the same principle as taking the course off the chart from the mag- netic rose instead of the true rose. Now, if there were any deviation on N by W' the correct magnetic bearing, of SE by E would show something else than SE by E on the compass when you took the bearing.. What- ever it is it would be the difference be- tween what you know the correct mag- netic bearing (SE by E) to be and what the compass says. The devia- tion, remember, would be for that point of the compass on which the vessel was heading and not for that point of the compass corresponding to the bearing. Bear this in mind. Showing both Ely. Var. and Dev.-- one point each. True north coincides Note.--We have used north in these examples in order to simplify matters, but remember that the rule applies to any point of the com- pass as well. Z "TAE. MARINE. REVIEW with N by W magnetic or correct magnetic. North magnetic or correct magnetic north, coincides with N by E true. That point of the compass (the ship's compass or deviation compass) that coincides with true north is NNW and N by W' on the Var. compass. It must be borne in mind that every com- pass is subject to variation if in a place where variation exists, and to devia- tion if within the disturbing influences 31 both Var. and Dev. It may be free from one or the other at times but hardly ever from both Var.. and Dey. at the same time. This is because the variation depends upon the locality the ship is in, and as there are only a few places on the earth where there is no variation, hence, it is seldom that a ship is where there is no variation.*. It is different with the deviation, which influence is caused by the dis- of iron and steel of the ship which turbing effects of the iron and steel TRUE | Wane WOT ny «a nin \ ny My WV yiqtlipsy,, % ly \» \*\ [4 : wr) \ lt WY Rs / She ss \ vo tlo VE So \ \ 20 2 . SPs SAO ay as, %% Lo > NY \uente boome,/ /4 Cae N sK--~ , A =e oo a =o ae S o= =a ps P= 23 -- 3 Et cor =. - : ~~ Za a RS eon ~ S gee = C57 ~ aS a Ss % S ", 2 Gage t/, . " 1 \ "yf, 3 ',/ ery \v o wy Mi Edel ays © \w l 2P hw' Whiyy}y Ho NO Aan yi Miliichiany x Yalu wi Showing no variation and no deviation. True N., Magnetic N. and Compass N. coincide with one another. Since there is no angle betw of the needle. gives rise to deviation. The three compass diagrams indicate the manner in which the compass is subjected when affected by variation and_ deviation. These diagrams indicate a compass in three conditions in respect to direction. The first condition (indicated by the outer circumference) represents the true directions.of the compass and they never change as do the Var. and Dev. compass. It is from this outer circumference that all true directions are first taken. These true directions are the same for all places on the earth. If a compass is free from both Var. and Dev. then the points at the circum- ference of its card will point just as they do on the card of the outer cir- cle; or in other words, the compass in- dicates true directions. It is seldom the case that a compass is free from een the three norths, there can be no deflection within the ship herself, hence, there- may be different headings of the ship where there is no effect, or in the case where adjusting has freed the compass from deviation. It is not often the case that a compass is entirely free from deviation even after 'careful ad- justment, and even 'if so it would not stay very long in that condition. When the ship is in a locality where variation exists the compass card with its points is slewed so that they do not coincide with the points of the com- pass indicating the true horizon. The second circumference, marked "Var. Compass," in the foregoing diagram, *NotE.--This is possible along the north shore of Lake Michigan, and also north of this. on Lake Superior (the line of no variation), where the variation is practically' nothing. A com- pass then free from deviation would show true directions, the same as that of the outer cir- cumference in the foregoing figure.