ene TET, BERS Fh IS ead oe ae ee ke 
Miscellaneous Intelligence. 135 
pressly for the purpose. Magnetic surveys have been completed of 
British North America at the expense of our own government,—and of 
tions which particular lines, or, as some may deem them, critical points 
in the magnetic resultants, may occupy on the earth’s surface at the 
present epoch. Such notices could only be as yet provisional, an 
liable to the amendments which more exact and extended calculation 
he magnetic phenomena, or as it is now customary to call them, 
the three magnetic elements, appear to be everywhere and in both 
hemispheres the resultants of a duplicate system of magnetic forces, 
unife d 
favorable conditions, the regularity of this movement can be se 
down to comparatively very minute fractions of time. By the results 
of careful observations, continued for several years at the Observatory 
of St. Helena,—where, in common with the greater part of the en 
of the South Atlantic, the secular change of the declination exceeds 
eight minutes in the year, and from its magnitude og ae = - 
vantageously studied,—every fortnight of the year is oa Le bh tg 
Precise aliquot portion of the annual amount of the secular change at 
the station. This phenomenon of secular change is undoubtedly one 
