88 
FIFTH REPORT— 1835 . 
the magnetic axes being each one third of the length of the 
earth’s axis, or Q = 3 ; and the ratio of the forces 1*7724 to 1. 
In comparing the phenomena as calculated by the aid of the 
above quantities and as observed in the eighty-four tabulated 
stations, it is seen, 1st, with regard to the Variation,—that except 
at places in the immediate vicinity of the magnetic poles no dis¬ 
cordance exists greater than about 5°. 2nd, In regard to the 
Dip, that the differences are generally inconsiderable, and mostly 
under 5°, except in a strip of the Atlantic extending from Tene- 
riffe in a south-west direction to about 14° N. latitude and 313 E. 
longitude, and in a strip of the Indian Ocean extending from 
the Straits of Babelmandel to the Indian Peninsula. In the At¬ 
lantic strip the calculated north dips are from 10° to 11° too 
small, and in the strip in the Indian Ocean the calculated north 
dips are about 10° or 12° too great, and the south dips as much 
too small. 3rd, In regard to the Intensities, the observed and 
calculated agree well, except in the aforesaid strip of the Atlan¬ 
tic, where the force as well as the dip is made too small by 
calculation ; manifesting that the elements still require some 
correction, which they will best receive when more observa¬ 
tions are obtained near the magnetic poles and along the line 
of no dip. 
The eighty-four stations which have served for the above 
comparison extend over the most important parts of the earth’s 
surface, both near the magnetic poles and the magnetic equator, 
and it is not probable that greater differences between the cal¬ 
culated and observed variations and dips will be found anywhere 
than those which appear in the table. 
M. Hansteen remarks in conclusion that most of the differ¬ 
ences would diminish, if not wholly disappear, by increasing the 
angle s, which the equatorial planes of the two magnetic axes 
form with the geographical equator. By increasing the angle s 
for the stronger axis the northerly dip in the northern part of 
the Atlantic, and the southerly dip in the Indian Ocean would 
increase, and the northerly dip consequently decrease between 
the Red Sea and India. Further, the westerly variation in 
Musketto Cove and in the Indian Ocean, near the Cape of 
Good Hope, and the easterly variation between Van Diemen’s 
Land and New Zealand would increase. By increasing the 
angle s for the weaker axis, the northerly dip in Petersburgh, 
Siberia, and Kamschatka, and the southerly dip near Terra del 
Fuego would increase ; and the westerly variation in Petersburgh 
and at the North Cape, and the easterly variation in Kams¬ 
chatka would decrease, whilst the easterly variation near Terra 
del Fuego would increase. It is also probable that this altera¬ 
tion would increase the calculated intensities in the Northern 
