|
|
|
|
|
|
|
MARYLAND GEOLOGICAL SURVEY
|
13
|
|
|
|
|
PAGE
|
|
|
|
The Mineral Paints................................................
|
222
|
|
|
|
The Diatomaceous Earth (Tripoli)...................................
|
222
|
|
|
|
The Mineral Waters..............................................
|
223
|
|
|
|
The Road-building Materials......................................
|
224
|
|
|
|
The Miscellaneous Products........................................
|
225
|
|
|
|
PART IV. BIBLIOGRAPHY AND CARTOGRAPHY OF MARYLAND, INCLUD-
|
|
|
|
|
ING PUBLICATIONS RELATING TO THE PHYSIOGRAPHY, GEOLOGY
|
|
|
|
|
AND MINERAL RESOURCES. BY EDWARD B. MATHEWS..........
|
229
|
|
|
|
Bibliography........................................................
|
231
|
|
|
|
Cartography........................................................
|
332
|
|
|
|
PART V. FIRST REPORT UPON MAGNETIC WORK IN MARYLAND,
|
|
|
|
|
INCLUDING THE HISTORY AND OBJECTS OF MAGNETIC SURVEYS.
|
|
|
|
|
BY L. A. BAUER..............................................
|
403
|
|
|
|
INTRODUCTION..........................................................
|
405
|
|
|
|
THE DEVELOPMENT A^D PURPOSES OF MAGNETIC SURVEYS..................
|
407
|
|
|
|
The Magnetic Declination............................................
|
407
|
|
|
|
The Secular Variation of the Magnetic Declination....................
|
411
|
|
|
|
The Magnetic Inclination...........................................
|
413
|
|
|
|
The Diurnal Variation of the Earth's Magnetism......................
|
418
|
|
|
|
The Intensity of the Earth's Magnetic Force..........................
|
418
|
|
|
|
The Elements involved in Magnetic Surveys..........................
|
421
|
|
|
|
Historical Summary of Magnetic Surveys..............................
|
425
|
|
|
|
GENERAL ACCOUNT OF THE MAGNETIC SURVEY OF MARYLAND................
|
432
|
|
|
|
Introductory Remarks................................................
|
432
|
|
|
|
Base Station.........................................................
|
435
|
|
|
|
Itinerary of Magnetic Trips..........................................
|
435
|
|
|
|
Selection of the Stations............................................
|
437
|
|
|
|
Methods of Observation.............................................
|
439
|
|
|
|
The Epoch selected for the Isomagnetic Maps.........................
|
449
|
|
|
|
Magnetic Instruments..............................................
|
450
|
|
|
|
THE VARIATIONS OF THE MAGNETIC DECLINATION..........................
|
453
|
|
|
|
The Special Purpose of this Chapter.................................
|
453
|
|
|
|
Periodic Variations..................................................
|
454
|
|
|
|
Minor Periodic Fluctuations..........................................
|
461
|
|
|
|
|
|
|
|
|
Magnetic Storms....................................................
|
461
|
|
|
|
The Secular Variation................................................
|
463
|
|
|
|
|
|
|
|
|
THE DISTRIBUTION OF THE MAGNETIC DECLINATION IN MARYLAND..........
|
486
|
|
|
|
Explanatory Remarks................................................
|
486
|
|
|
|
Table of Magnetic Declinations observed by the Maryland Geological
|
|
|
|
|
Survey............................................................
|
489
|
|
|
|
Table of Magnetic Declinations observed by the Coast and Geodetic Survey,
|
490
|
|
|
|
Isogonic Chart for 1900..............................................
|
492
|
|
|
|
Isogonic Charts for 1700 and 1800....................................
|
494
|
|
|
|
The Secular Motion of the Agonic line over Maryland..................
|
494
|
|
|
|
The Effect of the Secular Variation of the Magnetic Meridians..........
|
495
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
