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PROCEEDINGS OF 
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 con¬ 
tinued 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 coun¬ 
trymen . 
These combined observations, progressing throughout the world, are of the high¬ 
est importance. The University of Cambridge, the American Philosophical Socie¬ 
ty, and Girard College, have erected observatories ; and one connected with the 
Depot of Charts and Instruments, has been built last year in this city by the Gov¬ 
ernment, and thoroughly furnished with instruments for complete observations 
The names of Bache, Maury, 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, were 
first pointed out by Dr. A. D. Bache, whose researches, in conjunction with Lloyd 
of Dublin, to determine whether differences of longitude could be measured by the 
observations of small simultaneous changes in the position of the magnetic needle, 
led to the knowledge of the curious fact, that these changes, which had been 
traced as simultaneous, or nearly so, in the continent of Europe, did not so extend 
across the Atlantic. 
Kindred to these two branches, are electro-magnetism and magneto-electricity, 
connected with which, as discoverers, are our countrymen Dana, Green, Hare, 
Henry, Page, Rogers, and Saxton. The reciprocal machine for producing shocks, 
invented by Page, and the powerful galvanic magnet of Henry, are entitled to re¬ 
spectful notice. This force, it was thought, might be substituted for steam; but 
no experiments have as yet established its use, on any important scale, as a mo¬ 
tive power. The fact that an electrical spark could be produced by a peculiar ar¬ 
rangement of a coil of wire, connected with a magnet, is a recent discovery; and 
the first magneto*electric machine capable of keeping up a continuous current was 
invented by Saxton. 
Electricity and magnetism touch in some points upon heat. Heat produces electri¬ 
cal currents; electrical currents produce heat. Heat destroys magnetism. Melted 
iron is incapable of magnetic influence. Reduction of temperature in iron so far 
decreases the force, that a celebrated philosopher made an elaborate series of ex. 
periments to ascertain whether a great reduction of temperature might not develops 
magnetic properties in metals other than iron. This branch of thermo-electricity 
has received from us but little attention, Franklin’s experiments, by placing dif- 
