There are also districts in the
earth where the mariner, who has been enveloped for many days in mist,
without seeing either the sun or stars, and deprived of all means of
determining the time, may know with certainty, from the variations in the
inclination of the magnetic needle, whether he is at the north or the south
of the port he is desirous of entering.*
[footnote] *I have described, in Lametherie's 'Journal de Physique', 1804,
t. lix., p. 449, the application (alluded to in the text) of the magnetic
inclination to the determination of latitude along a coast running north and
south, and which, like that of Chili and Peru, is for a part of the year
enveloped in mist ('garua'). In the locality I have just mentioned, this
application is of the greater importance, because, in consequence of the
strong current running northward as far as to Cape Parena, navigators incur
a great loss of time if they approach the coast to the north of the haven
they are seeking. In the South Sea, from Callao de Lima harbor to Truxillo,
which differ from each other in latitude by 3 degrees 57' I have observed a
variation of the magnetic inclination amounting to 9 degrees (centesimal
division); and from Callao to Guayaquil, which differ in latitude by 9
degrees 50', a variation of 23.
Pages:
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374