Astro setup in Mojave Desert. Richard Cohen preparing to record in truck. Astro party of Lt.(j.g.) Albert Theberge

Vernon Burns preparing Wild T-4 for observations. Astro party of Lt.(j.g.) Albert Theberge

Richard Maxey setting up Wild T-4. Astro party of Robert A. Pryce

Vernon Burns at twilight - determining initial azimuth. Astro party of Lt.(j.g.) Albert Theberge

A. E. Theberge discussing Wild T-4 with Afghani student. Astro party of Lt.(j.g.) Albert Theberge

A. E. Theberge discussing Wild T-4 with Afghani student. Astro party of Lt.(j.g.) Albert Theberge

Latitude observatory at Ukiah, California. International program to determine variation of latitude

Use of Navy Transit satellite receiver. Determining latitude and longitude simultaneously. Multiple passes over several hours to get good position

Texas Instruments TI4100 GPS receiver. Determining latitude and longitude simultaneously

Use of Texas Instruments TI4100 GPS receiver. Determining latitude and longitude simultaneously

Use of Navy Transit satellite receiver. Determining latitude and longitude simultaneously

Jasper Bilby with light reconnaissance buggy. Recon work on the 98th Meridian

500 lb. stone being lowered for Brown Valley Base. 98th Meridian survey. Jasper Bilby on right

Marking complete for Station Stephen East Base. 98th Meridian survey

Setting mark on Station Twin. Triangulation party of William M. Scaife

Setting mark near White Pass

Driving mark into the muskeg. Crew from PIONEER

Deep driven rods for bench marks. Crew from PATHFINDER

Digging a hole for a bench mark

Using gas drill to drill hole for bench mark

Mixing cement to set bench mark

Mark after being set in ground

Different types of bench marks

Original Station Winton North Base. Mark displaced by steam shovel. Triangulation party of E. O. Heaton

Station Yolo SE Base. Triangulation party of Frank G. Johnson

Northwest Coast Indians deep-sixing bottle used as survey mark. Bottle set by party of George Davidson in 1852. Smallpox came after surveyors left. Indians felt bottle had evil spirits, dug up, and threw away

Reference bottle at Station Principio

Triangulation station at Meade's Ranch. Control point for the North American Datum

Historical monument explaining significance of Meade's Ranch. Control point for the North American Datum

Old reference mark for Deming South Base. Triangulation party of Frank G. Johnson

Hatcher Mountain Monument. Triangulation party of Frank G. Johnson

Monument showing effects of wind erosion

Ferdinand Hassler's observing tent. Probably the original sketch was by John Farley

View of summit station on Uncompaghre Peak - 14300 feet. 39th Parallel triangulation. Triangulation party of William Eimbeck

Observing station on Tushar Mountain - 12146 feet. 39th Parallel triangulation. Triangulation party of William Eimbeck

Observing station on Round Top - 10386 feet. 39th Parallel triangulation. Astro and triangulation party of George Davidson

Map of the 39th Parallel Arc. The first great geodetic arc in the western hemisphere

Instrument station near Station 189. "Care needed in moving". International Boundary Survey

Recorder attempting to find error in readings. International Boundary Survey

Triangulation station along 141st Meridian. Bandana for mosquitos. International Boundary Survey

White Pass West Base along the 141st Meridian. International Boundary Survey

Signal and small pole for observations on short lines. Triangulation party of J. B. Miller

Mosquito protection. Survey work along Kuskokwim River. Survey crew off the YUKON

Observing at triangulation station POW. Combined operations party of C. G. Quillian

Primary triangulation work. Combined operations party of _ Daniels

C&GS 12" theodolite. Used in Clarence Straits work

8" Wanschaff theodolite. Triangulation party of C. L. Garner

Observing tent used to shelter instrument from the wind. Triangulation party of E. W. Eickelberg

Station Caribou before being struck by lightning. William Scaife on left. Elevation 9816 feet. Triangulation party of William M. Scaife

Station Caribou after being struck by lightning - Elevation 9816 feet. Elevation 9816 feet. Triangulation party of William M. Scaife