Title: Magnetic variation in the United States
Description: 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.
Subjects: Geomagnetism, Secular variations
Places: United States