XVlil NOTES. 



and progressive movement which take place in the magnetic lines were still 

 wholly unknown to him : " varietas uniuscujusque loci constaus est." 



( 60 ) p. 59. Historia natural de las Indias, Kb. i. cap. 17. 



( 61 ) p. 59. Kosmos, Bd. i. S. 189; English edition, p. 171. 



( 82 ) p. 60. I have shown, from very careful observations of the Inclination 

 made by myself in the Pacific, what are the conditions under which the mag- 

 netic Inclination may be of important practical use in determining the latitude 

 during the prevalence of the "garua"or fog, which, at certain seasons on the 

 Peruvian coast, conceals the sun and stars. (Kosmos, Bd. i. S. 185 and 428, 

 Anm. 14; English edition, p. 168 and Note 144.) The Jesuit Cabius, the au- 

 thor of the " Philosophia magnetica" (in qua nova quaedam pyxis explicatnr, 

 quae poll elevationem ubique demonstrat), directed attention to this subject 

 in the first half of the 17th century. 



( w ) p. 60. Edmund Halley, in the Phil. Trans, for 1683 vol. xii. No. 148, 

 p. 216. 



( w ) p. 61. Such lines, called by him "tractus chalyboeliticos," had also 

 been drawn by Pater Christoph Burrus, at Lisbon, in a map which he offered at 

 an exorbitant price to the King of Spain, as mentioned by Kircher in his Magnes, 

 ed. 2. p. 443. The first Variation Chart ever constructed has been already 

 mentioned in p. 56. 



C 55 ) p. 62. Even twenty years after Halley had prepared, at St. Helena, his 

 Catalogue of Southern Stars (in which, unfortunately, there are none below the 

 6th magnitude), Hevelius, in the " Firmamentum Sobescianum," boasted of not 

 using a telescope, and of observing through longitudinal apertures. Halley had 

 been present at some of these observations (to the exactness- of which he gave 

 undue praise) when he visited Dantzic in 1679. Kosmos, Bd. iii. S. 60, 106 

 (Anm. 2 and 3), 154, 317, and 355 (Anm. 13); English edition, p. 43, xiv. 

 (Notes 91 and 92), 97, 221, and Ixxix. Note 370. 



( 66 ) p. 62. Traces of variations of the magnetic Declination on different 

 days, and at different hours, had already been remarked in London by Hellibrand, 

 1634, and in Siam by Pater Tachard, 1682. 



( 67 ) p. 63. Compare Kosmos, Bd. i. S. 432435, Anm. 29; English edi- 

 tion, Note 159. The excellent construction of the Boussole d'Inclinaison first 

 made by Lenoir, according to Borda's plan, the possibility which it gave of free 

 and long vibrations of the needle, the very great diminution of the friction of the 

 axles, and the steadiness and good means of adjustment of the instrument, which 

 was provided with levels, first made it possible to obtain exact measurements 

 of the differences of the Earth's magnetic force in different zones. 



C 68N p. 65. The numbers placed first in the table (as, for example, 1803 



