This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1917 Excerpt: ...had done when he started. The chart on the following page shows the declination of the magnetic needle throughout the United States in 1900. Isogonal lines connect places where the declination is the same. 493. Intensity of the Earth's Magnetism.--The magnetic force of the earth at any point may be considered as the ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1917 Excerpt: ...had done when he started. The chart on the following page shows the declination of the magnetic needle throughout the United States in 1900. Isogonal lines connect places where the declination is the same. 493. Intensity of the Earth's Magnetism.--The magnetic force of the earth at any point may be considered as the resultant of two component forces, the horizontal component H (Fig. 266), and the vertical component V. The horizontal component H is the force which is effective in directing the compass needle. The smaller this component the more feebly will the needle be affected. When a needle is balanced or suspended in the usual way so as to vibrate in a horizontal plane, its period of oscillation depends on this component only. As shown in paragraph 488, the intensities at different places may be compared by causing the same magnet to vibrate first at one place and then at the other. The intensities are proportional to the squares of the number of vibrations per second. By this means the horizontal component of the intensity may be determined at any point as compared with that at some standard place. When the horizontal intensity and the dip are both known, the resultant intensity may be found by the relation B--H-cos a when a is the angle of dip. The following table shows the value of the horizontal component and total force at certain places. Notice how the horizontal force becomes less in higher latitudes. The intensity is given in C. G. S. units, or the force in dynes upon a unit pole. Fio. 266. Strength of the Earth's Magnetic Field (Dynes per Unit Pole) 494. Secular Change in the Magnetic Field.--One of the most remarkable features of the earth's magnetism is that it is continually changing. The declination of the needle is slowly changing everywher...
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Seller's Description:
Fair. No dust jacket. Front hinge cracked. Minimal underlining in red ink. xii, 783 p. illus., diagrs. 22 cm. Includes Illustrations. Contains "References"
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PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
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Seller's Description:
PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
Choose your shipping method in Checkout. Costs may vary based on destination.
Seller's Description:
PLEASE NOTE, WE DO NOT SHIP TO DENMARK. New Book. Shipped from UK in 4 to 14 days. Established seller since 2000. Please note we cannot offer an expedited shipping service from the UK.
