332 
LITTLEHALES. 
netism as manifested at the Earth’s surface has never subse¬ 
quently been achieved, for, although national agencies in 
the United States, Great Britain, and Germany have since 
carried forward by progressive steps the portrayal of the iso- 
magnetic lines, there are still great continental areas where 
the distribution of terrestrial magnetic forces has never 
been measured and up to the present time no systematic 
survey of any of the oceanic areas has been made, but 
reliance has necessarily been placed upon collections of 
observations of the magnetic elements taken at widely differ¬ 
ent times and under every variety of circumstances. 
It will not be overlooked that out of Sabine’s remarkable 
system of records and tabulations grew the first compre¬ 
hensive representation of lines of equal values of the inten¬ 
sity of the Earth’s magnetic force. For a long time the 
method of vibrations was the only acceptable process in use 
for obtaining measures of magnetic intensity, and these 
measures, which were only relative and depended upon the 
magnetic moment of some arbitrarily chosen magnet, 
entered largely, through the observations of Bossel, D’En¬ 
trecasteaux, and Humboldt, into Sabine’s isodynamic charts. 
Coulomb, Hansteen, and Poisson all contributed more or less 
to the improvement of the method of vibrations for intensity 
measurements; and finally it reached perfection in the 
hands of Gauss who coupled it in a thorou ghly scientific man¬ 
ner with the method of deflexions and made the first abso¬ 
lute measure of the horizontal intensity of the Earth’s mag¬ 
netic force at Gottingen on the 18th of September, 1832. 
Karl Fiedrich Gauss, the first mathematician of the nine¬ 
teenth century, was the demi-god who made the magnetism 
of the Earth an agency for the scientific investigation of 
terrestrial physics. The fundamental processes upon which 
all the exact sciences rest are weighing and measuring; and 
it was Gauss who first measured the terrestrial magnetic 
force in terms of the fundamental units of space, mass, and 
time, and who devised the first magnetometers and instru¬ 
ments for the registration of the momentary and ephemeral 
