244 



THE NATIONAL GEOGRAPHIC MAGAZINE 



METHODS O? CARRYING INSTRUMENTS 



AND BAGGAGE IN NORTHERN 



CANADA 



shown at St Johns, N. F., last Septem- 

 ber, a card furnished to a coast hner by 

 a New York compass-adjuster. This 

 card was so manifestly wrong and im- 

 possible that, if the captain himself had 

 not suspected its incorrectness and had 

 not made observations at the earliest 

 opportunity when his vessel left port, 

 she would surely have gone ashore. 



When some years ago a great liner 

 was wrecked by going on the rocks, there 

 was a great deal said about "local mag- 

 netic attraction of the rocks," where, as 

 a matter of fact, practically no attraction 

 existed. It is of interest to know, how- 

 ever, that the same man who had ad- 

 justed the compasses on board that liner 

 had previously performed a similar duty 

 on a private yacht whose owner, a scien- 

 tific man, found just in time that grave 

 errors and "misadjustments" had been 

 made. This may be simply a coincidence, 

 but there is no question that a captain 



cannot wholly trust to adjustments made 

 for him, and that he must have the 

 means of checking up as often as pos- 

 sible. For that purpose he must know,, 

 in the first place, just what the correct 

 or undisturbed "variation" or direction 

 of the compass is in all the waters he 

 is likely to traverse. 



LOCAL ATTRACTIONS OE THE COMPASS 



One further source of danger to navi- 

 gation must be cited. A number of re- 

 gions have been found which attract 

 the compass, due frequently to large- 

 local deposits of magnetic iron ore.. 

 These regions thus have the same efifect 

 as the iron on board ship, with this- 

 difference, however, that, in general,, 

 they exert a constant effect, which, when 

 once determined, can thereafter be al- 

 lowed for. For example, the Madeiras,, 

 the Bermudas, and, in general, islands of 

 volcanic origin are places of more or less 

 pronounced local attraction. Along the 

 inner passage from Seattle to Alaska,, 

 there are several places where the at- 

 traction from the shore is so strong as. 



MAGNETIC OBSERVER AT WORK IN CANADA 



