Modified stierle tide gauge, model of 1896. Plate No. 4 of Appendix No. 7. Part II, Report of the Superintendent ... 1897, p. 318

Saxton self-registering tide gauge, model as of 1897. Plate No. 3 of Appendix No. 7. Part II, Report of the Superintendent ... 1897, p. 318

Magnetic declination and dip station. Observations at Boundary Marker No. 1. This was at the northernmost point on the Alaska-Canada Boundary. Party of J. T. Watkins - transportation by Coast Guard Cutter Bear

Magnetic observations by party of J. T. Watkins. Station was about 10 miles west of East Cape, Siberia. Transportation by Coast Guard Cutter Bear

Magnetic observations by party of M. L. Cleven.

Magnetic observations by party of M. L. Cleven in east-central Alaskan Arctic.

Observing magnetics with transit magnetometer at Station Mir 2. Party off of EXPLORER

Observing absolute value of horizontal component of the Earth's magnetic field.

Measuring absolute value of declination with a declinometer.

Co-tidal lines of the world.

Making magnetic observations for declination.

Chart showing isogonic lines for year 1900. Isogonic lines are lines of equal declination

Magnetic station near El Misti Volcano, Peru. Party of James Baden

Transit magnetometer station.

Transit magnetometer station. Party off of PATHFINDER

Using compass declinometer for magnetic observations. Lt. Benjamin H. Rigg observing. Accompanied MacMillan Arctic Expedition.

Lt. B. H. Rigg making magnetic observations in Canadian Arctic. Accompanied MacMillan Arctic Expedition

Lt. B. H. Rigg preparing to make magnetic observations in Canadian Arctic. Accompanied MacMillan Arctic Expedition

A Z-Variometer. Instrument measures relative changes in vertical component of Earth's magnetism

Magnetic station at Hobhouse Inlet. Party of Joel Campbell

Lt. Charles A. Schoene observing magnetics at Little America IV. Schoene accompanied Operation High Jump

Magnetic observatory at Little America IV. Tent used for absolute observations while center building used for variation

Chart showing isogonic lines for year 1900. Isogonic lines are lines of equal declination

Brown Gravity Meter - a pendulum apparatus.

Brown Gravity Meter pendulum apparatus.

Observing gravity inside the cave at Station Jaggar. Party of E. J. Brown

Gravity and radio apparatus on Necker Island. Observations as part of World Longitude Network. Party of E. J. Brown

Lt. Joseph Lushene observing gravity in Bahamas. Cooperative project with the Navy and F. A. Vening Meinesz

Lt. Carl Aslakson observing gravity during South American expedition.

Measurements in strain in rock at Dugway Proving Ground.

Why the rock was being strained. 1/2 scale explosion at Dugway Proving Ground

Triangulation observations following major earthquake.

Triangulation observations following major earthquake.

Lieutenant Harley Nygren conducting gravity observations for Sandia Corporation.

Reproduction of first map showing magnetic declination in the United States. First published by the Coast Survey in 1856

Underground magnetic observatory built at the University of Wisconsin in 1870's. Built under direction of Coast Survey. Observations made to Coast Survey specifications. One of many academic geophysical observatories built under guidance of C&GS

Magnetic observations along the Yukon River.

Coast Guard Cutter Bear at Demarcation Point. Provided transportation for magnetic field work by C&GS officer J. T. Watkins

Magnetic observations at sea on the C&GS Ship BACHE.

Early use of proton precession marine magnetometer. Deployment of towed magnetometer on C&GS Ship PIONEER

Brown pendulum apparatus gravity meter. Named for its inventor, Lt. E. J. Brown, C&GS. Lt. Brown died in an automobile accident in 1935.

Mendenhall half-second pendulums. Figure 2 of William Bowie's "Investigations of Gravity and Isostasy"

Gravity observing apparatus. Figure 3 of William Bowie's "Investigations of Gravity and Isostasy"

Original form of Mendenhall half-second pendulum gravity measuring apparatus. Figure 3 of William Bowie's "Investigations of Gravity and Isostasy"

Ground shaker at Position "B". Used to determine earthquake engineering characteristics of buildings. C&GS was the first organization to undertake engineering seismology studies. Party of William D. Patterson

Building shaker in the doorway of a building. Used to determine earthquake engineering characteristics of buildings. C&GS was the first organization to undertake engineering seismology studies. Party of William D. Patterson

Ground shaker at Position "A". Used to determine earthquake engineering characteristics of buildings. C&GS was the first organization to undertake engineering seismology studies. Party of William D. Patterson

Deployment of towed magnetometer on C&GS Ship PIONEER.

Bank of recording instruments at Honolulu geophysical observatory. Recording tidal levels at remote sites throughout Pacific Basin. Used for tsunami warning system.

Bank of recording instruments at Honolulu geophysical observatory. Recording tidal levels at remote sites throughout Pacific Basin. Used for tsunami warning system.