296 TERRESTRIAL MAGNETISM.—MURPHY. 
as well as other recent determinations for Newcastle, Scarborough, 
Whitehaven, Cardiff and Falmouth. This comparison gave the 
compilers the means of correcting as necessary the maps brought 
up from Sabine and Evans in the way mentioned. There are of 
course practically local peculiarities or irregularities which can- 
not be considered in such a map. 
The whole of Europe, excepting a small part of Russia, has 
now a western declination, while at the close of the seventeenth 
century the needle first pointed due north in London, in 1657, 
and in Paris in 1669,—there being thus a difference of twelve 
years, notwithstanding the small distance between these places. 
Hunsteen and Erman shew the remarkable double curvature of 
the lines of declination in the region of Northern Asia. On the 
13th of September, 1492, Columbus found a line of no variation 
3° west of the meridian of the island of Flores, one of the Azores, 
Gilbert says that in 1600 the declination was still null in the 
region of the Azores, just as it had been found by the discoverer 
of the New World. Columbus attached great importance to the 
zone in which the compass showed no variation. In the begin- 
ning of the present century, at an elevation of 11,936 feet above 
the level of the sea, Humboldt made an astronomical determina- 
tion of the point (7° 1’ south lat. 48° 40’ west longitude from 
Paris), where, in the interior of the new continent, the chain of 
the Andes is intersected by the magnetic equator between Quito 
and Lima. The more recent observations of Sabine have shewn 
that the node near the island of St. Thomas moved 4° from east 
to west between 1825 and 1837. In London the needle pointed 
to the east of north before the year 1657, when it pointed due 
north. From that time the westerly declination gradually in- 
creased until the beginning of the present century, when the 
westerly motion was observed to flag. In 1819 the greatest 
westerly declination was reached. At this time the needle 
pointed 242 degrees to the west of north. Since then the needle 
has been slowly travelling eastwards, and the westerly declina- 
tion is now only some 17° west of north. 
In Paris the needle pointed due North in 1663, it ceased to 
move westwards in 1817, and the greatest westerly declination 
attained was only 224 degrees. — 
