e observations on the variations of the needle made by
Winthrop and Dewitt, deserve notice and commendation. Not long since,
Gauss, of Germany, invented instruments by which the changes of magnetic
variation and force could be accurately determined. Magnetic action is
ever varying. The needle does not point in the same direction for even a
few minutes together. The force of magnetism, also, perpetually varies.
'True as the needle to the pole' is not a correct simile for the same
place, and, if we pass from one spot to another, is falsified at each
change of our position; for the needle changes its direction, and the
force varies. Enlarged and united observations, embracing the various
portions of the world, must produce important results. The observations
at Philadelphia, conducted by Dr. A. D. Bache, and now continued by him
under the direction of the Topographical Bureau, are of great value, and
will, it is hoped, be published by Congress. Part of them have already
first seen the light in Europe--a result much to be regretted, for we
are not strong enough in science to spare from the national records the
contributions of our countrymen.

These combined observations, progressing throughout the world, are of
the highest importance. The University of Cambridge, the American
Philosophical Society, and Girard College have erected observatories;
and one connected with the Depot of Charts and Instruments has been
built in this city last year by the Government, and thoroughly furnished
with instruments for complete observations. The names of Bache, Gillis,
Pierce, Lovering, and Bond are well known in connection with these
establishments.

A magnetic survey of Pennsylvania has been made by private enterprise,
and the beginning of a survey in New York. Loomis has observed in Ohio,
Locke in Ohio and Iowa, and to him belongs the discovery of the position
of the point of greatest magnetic intensity in the Western World. Most
interesting magnetic observations (now in progress of publication by
Congress) are the result of the toilsome, perilous, and successful
expedition, under Commander Wilkes, of our navy, by whom was discovered
the Antarctic continent, and a portion of its soil and rock brought home
to our country.

The analogy of the auroral displays with those of electricity in motion,
was first pointed out by Dr. A. D. Bache, whose researches, in
conjunction with Lloyd of Dublin, to determine whether differences of
longitud