The Earth a Great Magnet: A Lecture Delivered Before the Yale Scientific Club, February 14,1872C.C. Chatfield & Company, 1872 - 2 pages |
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ALFRED MARSHALL Amer aurora axis bar magnet bar of iron bar of soft beams Brazil bring called centre coil columns copper wire Cosmos current of electricity curves deflection diameter dipping needle direction disc discovery distance earth electric current electro-magnet evolved experiments fact Faraday feet galvanometer Gilbert glass plate Haven hemisphere hold inches inductive iron cores iron filings Jourl lantern-needle lecture light lodestone lower end magnetic condition magnetic equator magnetic force magnetic lines magnetic needle meridian motion move needle points needle swings needle's netic north end north magnetic pole north magnetism observe parallel permanently magnetized Ph.D place its length plane polarity Porto Seguro pounds Prof rays red end reverse screen shellac Sir James Ross soft iron south point southern hemisphere spear spear-end spools STEVENS INSTITUTE sun's surface suspended terrestrial magnetic tion tricity truth vertical vibration white end William Gilbert YALE SCIENTIFIC CLUB
Popular passages
Page 262 - Gravity must be caused by an agent acting constantly according to certain laws, but whether this agent be material or immaterial I have left to the consideration of my readers.
Page 262 - That gravity should be innate, inherent, and essential to matter, so that one body may act upon another at a distance through a vacuum, without the mediation of anything else, by and through which their action and force may be conveyed from one to. another, is to me so great an absurdity that I believe no man, who has iu philosophical matters a competent faculty of thinking, can ever fall into it.
Page 268 - It teaches to deduce principles carefully, to hold them firmly, or to suspend the judgment, to discover and obey law, and by it to be bold in applying to the greatest what we know of the smallest. It teaches us, first by tutors and books, to learn that which is already known to others, and then by the light and methods which belong to science to learn for ourselves and for others ; so making a fruitful return to man in the future for that which we have obtained from the men of the past. Bacon in...
Page 268 - ... pure or applied. It teaches a continual comparison of the small and great, and that under differences almost approaching the infinite: for the small as often contains the great in principle as the great does the small; and thus the mind becomes comprehensive. It teaches to deduce principles carefully, to hold them firmly, or to suspend the judgment: - to discover and obey law, and by it to be bold in applying to the greatest what we know of the smallest. It teaches us first by tutors and books...
Page 269 - Gilbert's to affirm, that it contains almost every thing that we know about magnetism. His unwearied diligence in searching every writing on the subject, and in getting information from navigators, and his incessant occupation in experiments, have left very few facts unknown to him. We meet with many things in the writings of posterior inquirers, some of them of high reputation, and of the present day, which are published and received as notable discoveries, but are contained in the rich collection...
Page 241 - To this we beg leave to suppose, that this subtile matter, no otherwise discovering itself but by its effects on the magnetic needle, wholly imperceptible, and at other times invisible, may now and then, by the concourse of several causes very rarely coincident, and to us as yet unknown, be capable of producing a small degree of light ; perhaps from the greater density of the matter, or the greater velocity of its motion : after the same manner as we see the effluvia of electric bodies, by a strong...
Page 268 - ... and methods which belong to science to learn for ourselves and for others ; — so making a fruitful return to man in the future for that which we have obtained from the men of the past. Bacon, in his instruction, tells us that the scientific student ought not to be as the ant, who gathers merely ; nor as the spider, who spins from her own bowels; but rather as the bee, who both gathers and produces.
Page 238 - This illumination consisted chiefly of luminous beams or columns, everywhere parallel to the direction of a magnetic needle when freely suspended ; that is, in the United States these beams were nearly vertical, their upper extremities being inclined southward at angles varying from 15° to 30°. These beams were, therefore...
Page 206 - This reciprocal action is subject to mechanical laws, unknown up to the present time. Professor Mayer, reaffirming Gilbert's doctrine that the earth is a great magnet, remarks that the mysterious variations in the intensity of its force seem to be in subjection to emanations from the sun, "changing with the apparent daily and yearly revolutions of that orb, and pulsating in sympathy with the huge waves of fire which sweep over its surface.
Page 245 - ... anxious gaze on me ; The polar star is dim, And driven darkness is awake With ocean's awful hymn! For I commune with spirit forms, Within my wizard cell, And mantling midnight melts before The magic of my spell. By many long, enduring links I clasp the northern star — And on the wiry-shadowed chain i I visit her afar.