430 FIRST REPORT UPON MAGNETIC WORK

Professor Bache declared that between his own map and that of
Loomis, when proper allowance was made for the secular change, " the
agreement was remarkable. " This epoch of about 1840 is remarkable
for the number of zealous, devoted and unselfish students of terrestrial
magnetism.

From 1878-1883, Professor Francis E. Nipher, Professor of Physics
at the Washington University of St. Louis, undertook a detailed
magnetic survey of Missouri. Professor Nipher must be duly cred-
ited with the spirit and enterprise he exhibited in the inauguration
of this survey. He was dependent entirely upon private aid for the
defraying of the expenses of the work. The instruments were loaned
by the Coast and Geodetic Survey. Professor Nipher has published
thus far five reports of this work. ¹ He has, however, not been able
to complete the survey, and so no final report and no maps have been
published. Pie had observed, with the aid of assistants, at 149 sta-
tions, or on the average at one station to 438 square miles.

At the same time some preliminary observations appear to have
been made by Professor Gustav Hinrichs in Iowa, but the survey does
not seem to have progressed far beyond a mere beginning.

We next come to the declination survey carried out—this time
under state auspices—under the direction of Professor George H.
Cook, then State Geologist of New Jersey, now deceased. The epoch
of the survey was 1888-90, all the observations to the extent of 158
stations having been made within a few years of this date. There
was thus on the average one decimation station to about 52 square
miles. The observations were not made with special magnetic instru-
ments, but good surveying transits were used. The observers appear
to have executed the work as carefully as the methods and instru-
ments would permit. " During October, 1887, two parties were placed
in the field, each supplied with good surveying transits, the needles
of which were six inches in length, and had been put in perfect order
and carefully compared with each other and with a standard needle.
... In this way observations were obtained at 121 localities within
a period of six weeks. " Let us say that each party consisted of two

¹ Transactions of the St. Louis Academy of Sciences, 1878-1886.