Magnetic variation in the United States

Magnetic Variation in the United States: Being a Compilation of Observations Made in Maerical from the year 1640 to the Present Date; Tabulated and Arranged for the use of Surveyors, with a brief account of the nature of Terrestrial Magnetism, its various theories as to the Origin, its Change in Intensity and Direction, and the progress of Magnetic Observation. by J.B. Stone, Ph.B, C.E., Formerly instructor in Mathematics in the Sheffield Scientific School of Yale College New York; 1878 Approximately 5" X 7 1/2"; 139 pages Contents: Part I: Preface Discovery of Variation and Dip Researches of Halley, Humboldt and Ross Table of Variation in London from 1576 to 1865 Change and Reversion of Change in Variation "Magnetic Crusade" of 1835 First Compilation in America Cause of Terrestrial Magnetism Theories of Mayer, Gauss, Ampere and Norton Magnetic Storms - Loomis' Conclusions Magnetic Intensity, Remarks and Table Accuracy of the Surveys by the Compass Lack of Information Concerning Variation in Text Books on Surveying Method of Ascertaining Variation by Theodolite and Compass Formation of Variation Tables of Any Locality Authors Method of Interpolation Author's Request for Reports on Observations Part II: Description of Tables Part III: Tables of Variation, Dip and Intensity Index On the back of the contents page there is an advertisement for Heller & Brightly Engineering and Surveying Instruments at 33 N. Seventh St., Philadelphia. There is also an advertisement for Brandis & Teckritz Instruments with a nice picture of a surveying device on the page previous to the Index.