Leveling on a cold winter's day. Level party of William Gibson

Carrying the fire bucket for cold fingers and frozen fountain pens. Level party of William Gibson

A seven observing party level party with its trucks and equipment. Level party of William Gibson

Observing in the Boundary Waters area of Minnesota. Level party of J. D. Thurmond

Leveling along the Loon River. Level party of J. D. Thurmond

Rodman driving footpin for rod while submerged. Level party of J. D. Thurmond

Leveling along the trail to Prairie Portage. Level party of J. D. Thurmond

Level party at Whisky Pass, 12,800 feet. Level party of Gilbert R. Fish

Level party at Whisky Pass, 12,800 feet. Level party of Gilbert R. Fish

Level party at Whisky Pass. Level party of Gilbert R. Fish

Level party in New York City. Level party of Charles D. Meaney

Extent of 1st and 2nd order level net as of July 1, 1936. W.P.A. computation party of Ralph Pfau

Leveling - river crossing on the lower Mississippi River. Level party of Karl Jeffers

Leveling - river crossing on the lower Mississippi River. Level party of Karl Jeffers

Leveling on the "low line" at Hoover Dam. Level party of Emmett Sheridan

Leveling at Mormon Mesa, Lake Meade area. Level party of Emmett Sheridan

Leveling on the "low line" at Hoover Dam. Note Hoover Dam in background. Level party of Emmett Sheridan

Leveling - scene of Colorado River crossing near Overton. Level party of Emmett Sheridan

Rodman holding rod steady for observations. Bench mark as seen from highway. Level party of Gilbert C. Mast

Level unit traveling along Glenn Highway. Level party of Gilbert C. Mast

Level observations along the Salmon River. Note rod just to right of umbrella. Level party of Ira Rubottom

Fording river during the course of the day's leveling. Level party of Ira Rubottom

A typical instrument position during Salmon River leveling. Level party of Ira Rubottom

A typical rod position during Salmon River leveling. Level party of Ira Rubottom

Instrument man signaling rodman to move to left. Level party of Ira Rubottom

Bench mark setters transportation during Salmon River leveling. Level party of Ira Rubottom

Leveling through the snow. Level party of Ira Rubottom

Leveling through the snow. Level party of Ira Rubottom

First order level observations in Brazil. Special training mission of Joseph Lushene

Zeiss level instrument at the Instituto Geographico Militar. Special training mission of Joseph Lushene

Leveling upper mark with accuracy only to cms. Special training mission of Joseph Lushene

Level party crossing bayous near Dugdemona River. Level party of R. C. Darling

Not the best bridge, but it will work. Level party crossing bayous near Dugdemona River. Level party of R. C. Darling

C. F. Ellingwood recording during leveling of White House. Level party of Howard Rappleye

E. J. Parkin observing levels at White House, South Portico. Level party of Howard Rappleye

Leveling operations on Anacapa Island. Carrying elevation from bench mark up vertical cliff. Note steel tape. Level party of Lorne G. Taylor

Leveling operations on Anacapa Island. Carrying elevation from bench mark up vertical cliff. Note steel tape and lighthouse in background. Level party of Lorne G. Taylor

Leveling operations at the White House. Level party of Howard Rappleye

Teaching Liberians precise leveling techniques. Party of George Morris

Mechanized level crew moving up. Level party of Emerson E. Jones

Rodman in the Louisiana mud.

Ferdinand Hassler directing movement of the Great Theodolite on Fire Island. Angle measurements at the end points of the Fire Island Base Line. Probably sketched by Assistant John Farley

Packing to the top - Bill Scaife leading the way up. Triangulation party of William M. Scaife. Upper Cook Inlet to Fairbanks

Packing to the top - sheer fortitude kept him going. Triangulation party of William M. Scaife. Upper Cook Inlet to Fairbanks

On Northwestern Glacier. Off of WILDCAT. Combined operations party of Paul A. Smith

Climbing to a station. Off of WILDCAT. Combined operations party of Paul A. Smith

Climbing to a station - the level of difficulty has increased. Off of WILDCAT. Combined operations party of Paul A. Smith

Back packing party preparing to leave the ship. On their way to shore in a skiff. Photo sheet No. 1 of sequence

Underway and resting enroute. Off of EXPLORER. Photo sheet No. 2 of sequence

Stopping for lunch and a rest enroute. Off of EXPLORER. Photo sheet No. 3 of sequence