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30 is her general magnetic character, which so to speak was born with the ship, and that portion due the individ- ual masses of vertical and horizontal iron is called induced magnetism. The sub-permanent magnetism is so-called 'in order to distinguish it from the- permanent: magnetism of steel mag- nets. DEVIATION FROM INDUCED MAGNETISM. The general magnetism (sub-perma- nent) of the ship after becoming sta- ble .in amount remains so, and the "color of its poles is 'not subject to change no matter which geographical direction and position the vessel may be in; but not so with the ship's in- duced magnetism, which is due to de- tached pieces of iron in a ship, such -as iron (or steel) masts, funnels, cyl- inders, and other masses of vertical iron, and are therefore independent magnets; it is of a transient kind, and the color of its poles depends upon the magnetic latitude the ship may be in at the moment; and in the case of horizontal iron, upon the direction of the ship's head. IT DOES NOT RETAIN IT ALL. When a bar'magnet is first mag- netized it will take a good deal more magnetism than it can possibly retain, and for several months afterwards gradually loses its strength until it set- tles down to a definite state known as saturation point, and accordingly is styled a permanent magnet. In this respect the ship and magnet are very much the same. -- Wous, to simplity matters let the ship's magnetism represent the mag- netism of an ordinary bar magnet, and do not let other complications bother your head for the present. ship's magnetism, taken as a whole, and the magnetism of the bar magnet, © are similar and for all intent and pur- poses may be so regarded by the stu- dent as having the same laws and _ principles. WHERE THE DEVIATION IS SYMMETRICAL. In nine cases out of every ten in vessels where the iron or steel' is sym- metrically placed, that is, as much at- traction on one side of the compass as there is repulsion on the other, as well as from. the bow to stern, the natural deviations* will be opposite in name and direction on reverse points of the compass, and practically of the same amount. For instance, if the deviation is easterly on north, say *The natural deviation is the attraction or repulsion of the ship's compass needle before the compass is adjusted or compensated, that is, just as the combined magnetism of the ship affects the compass, and no attempt made to counteract it. The deviation existing after the compass has been properly adiusted is called residual error (that which is left) being due to the unequal effects of the attraction and repulsion. This is fully explained under compass adjusting. Tanges over your stern? So far, the TAE Marine KEVIEW one point, it will be westerly on south about the same amount; or if it had been westerly on north it will be eas- terly on south, and so on round the com- pass. It must be borne in mind, however, that the magnetism of Figs. 1, 2 and "3. Fepresent but a particdlar case; for the iron of a ship may be, and in all iron ships is, differently disposed; but the diagrams will illustrate the' man- ner in which the deviation forms. QUESTIONS FOR WHEELSMEN AND WATCHMEN.--NO. 26. 261.' What marks can you use "for a turning point at Pt. au Frenes bound down? 262. How would you navigate a boat from abreast of Lime island dock. to abreast of Sweets Pt. crib? 263. boat from Sweet's Pt. crib until you had Frying Pan island and Pipe island 264. Give correct magnetic course and distance from abreast of Pt. Iro- quois lighthouse to a point one mile north of White Fish point lighthouse? 205. Give true course and. distance from a point one mile north of White Fish Point lighthouse to a point four miles north of Copper Harbor light- house. -- 206. Give correct magnetic course and distance from a point four miles north of Copper Harbor lighthouse to a point four miles north of Eagle Har- bor lighthouse? 267, Give correct magnetic course and distance from a point four miles north of Eagle Harbor lighthouse to a point one mile NxW'4W from Devil island lighthouse? 268. Give correct magnetic course and distance from a point one mile N xW!42W from Devil island lighthouse to Duluth harbor entrance? 209. Give correct magnetic course and distance from a point one mile north of White Fish Pt. lighthouse to a point four miles north of Big Pt. Sa- ble lighthouse. 270. Give correct magnetic course and distance from a point four miles north of Big Pt. Sable lighthouse to Marquette harbor entrance. QUESTIONS FOR OILERS AND WATERTENDERS.--NO. 21. 200. Would there be any difference in the actual reading of the steam gauge and the boiler pressure should the gauge be placed 15 ft. below the water line in the boilen if so, how much? e201. < At -what temperature does How would you navigate a water occupy the least amount of space, yet weigh the most, per cubic ft.? 202. How would you _ proceed to - line up a pair of links and connections to prove they were parallel? 203. How would you find the prop- er length of a valve stem? 204. How would you get the exact length of a piston rod? 205. How would you proceed to convince yourself a steam reverse en- ~ gine, countershaft, etc., were in their exact position? 206. In boring out a pair of crank pin shells would you bore them the exact size of pin? ; 207. What size would you suggest a pair of crosshead brasses to be bored for a 6-in, pin? 208. How would you lay up a com- pound duplex feed pump for the win- ter? 209. What is the quickest and saf- est way of laying up the forward line for winter? ' QUESTIONS FOR MASTERS AND MATES.--NO. 25. _ 370. The correct magnetic course is NE and the compass course is NE by EI4E, how much and which way is the - deviation? 371. What is the difference between a correct magnetic course and a com- pass course? 372. The correct magnetic bearing of a range is SSE, when on with this range your steering compass reads S Y%ZE, how much and which way is the deviation? an The deviation on N by BY correct magnetic is 6 degrees Wly., what compass course would you steer trom. Chicaso to-Pt.. Betsey. by such compass? 374. The true bearing of the sun is SSW the Var. is %4-pt. Ely. and the bearing of the sun by compass is SW | 7%S, how much and which way is the deviation? 375. Your steering compass has a deviation of 5 degrees Ely. on a cor- rect magnetic course of SW by W, how would you steer with this com- pass from Devil's island to Duluth? 376. If the correct magnetic course is to the right of the compass course what name does the deviation take? 377. If the compass bearing is to the right of the correct magnetic bear- ing what name does the _ deviation take? 378. On the course from Eagle Har- bor to Ashland via South passage, your steering compass says W by S%S, and a good course is made of it, how much and which way is the deviation of this