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TAE Marine Review : i= 2. \\\\\ / 9 w\\ \ | | / MN bk . . ee / i Pg S 7 (0 Oo << vee Pas Ae S & Ch. ys Se ee a ao Lee 06 W abe E ae Oar, = SHADOW DIAL. acu i oe STE 0p eZ Sf | te ae Wy SS Kus Ur il\| Whos a Uy § 2 8 & BS FIG. 29, had swung your ship "on ranges. By referring to Fig. 27 you will see that our ship headed north half west when she should have headed _ northeast, she should have headed north, north- east quarter north, when she should have headed northeast, etc. How to Make a Practice Pelorus. A simple little instrument can be made with very little trouble that will do for all practice work. As it would be somewhat difficult for you to make a perfect dial we give here a cut of an arrow dial, Fig. 28, and also a cut of a shadow dial, Fig. kK-SHADOW P/N [ = if | CARD DIAL | A : y S a > ¥2e a | ' | BASE BOARDER" your 29, Cut these out and paste one .on each side of a piece of cardboard that is cut the same size: you a reversible dial. If you wish to use the shadow pin you will simply have to turn the side marked "Shadow Dial" uppermost. If you want to use the arrow dial then use the other side of the card. : You will now need a piece of inch board for a base. See Fig. 30. Cut this a little larger than the dial but make it Square instead of round. Six inches square would be a good size. If you are going to use the shadow dial then very little remains to com- plete your instrument. Lay your carboard dial on the baseboard and stand a knitting needle upright in the middle, driving it through the card- board dial and into the base at least half an inch. The dial will now turn on the base in any direction. Choose one side of your base for the forward side and mark a lubber-line directly in the middle. This will represent ship's head. This now com- pletes your shadow, pelorous. With this kind of a pelorous you must get 'the azimuth from the book before you take a bearing. Then find the azimuth on your dial and swing the dial around until this azimuth is at the mark that shows your ship's head. The sun will then cause the needle This will make - 29 to throw a shadow on the 'magnetic course the ship is steering. _Remem- ber that the azimuth you get from the book is a "true" azimuth. You must find the variation of the locality you are in and apply it to this true azimuth before you put it at the ship's head. If you wish to use your pelorous -- as an arrow dial you will need a sight vane in place of the knitting needle. You must also reverse' 'your cardboard dial--using the side marked "Arrow Dial." A' sight vane need be a very simple affair, A piece of wood can be cut about the size and shape of a lead pencil. Stand this in the center of your card "in the place of the knitting needle. You can bore a hole through your card 'and into the base if you wish, but a better way would be to put a short piece of knitting needle into the bot- tom of your stick and then insert it in the same hole your shadow pin made. If you made a hole in the baseboard large enought to insert the stick you would spoil your base- board and your card as a shadow in- strument, You will now need a sight vane at the top of the stick and a pointer near the bottom. See Fig. 31. Bore a small hole near the bo:tom of the stick and insert a knitting needle. Have this piece of needle just long enough so that it will come to the © row of figures on each side of the -- POINTER Fic, 312 A oe Se, card. This will be your pointer. Now cut a slit in the top of your stick (like the slit in a clothes pin, only shorter) and swing a flat piece of stick in this slit for a pointer. Fasten it there with a short screw or nail. This completes your pelorous. Now try it. Set it near your compass and -- square it up, fore and aft, with the