GPS antenna set up over mark close to lumber camp in Icy Bay.

Close-up of home-made radar reflector constructed from house insulation covered with aluminum foil. These reflectors were placed over GPS determined positions and used to control an airborne synthetic aperture radar survey of Icy Bay.

Close-up of home-made radar reflector constructed from house insulation covered with aluminum foil. These reflectors were placed over GPS determined positions and used to control an airborne synthetic aperture radar survey of Icy Bay.

Mike Aslaksen surveying the beach with kinematic GPS mounted on an all-terrain vehicle.

Loading equipment in skiff to transport radar reflectors, GPS antennas, etc. to remote sites around Icy Bay. Shot gun was for protection from potentially hostile bears.

Unloading gear from bush aircraft used for transportation from Yakutat.

One mode of transportation used by lumberjacks in Icy Bay.

NGS Triangulation Party G-19 in Cabool, Missouri. Party chief, Lieutenant John Oswald standing in center with son on shoulders.

Sign on side of field party trailer designating Party G-19.

Bilby Tower with one super (10-foot extension). Approximately 123 feet total to the top.

G-19 building trucks with backhoe for digging.

Leonard Bergman, building foreman, leveling site for the tower.

Donny McFarland digging tower anchor hole.

After anchor holes dug, laying out steel for tower construction.

Setting anchors for inner and outer towers.

Inner and outer tower legs attached to anchor boards of Bilby tower.

Attaching the first the first thirteen-foot section to the anchors.

Fred Buck on tower beginning construction of Bilby tower.

Attaching cross-ties to begin support for second thirteen-foot section of Bilby tower.

Builder Donny McFarland securing the second leg section.

Securing the second leg section - five of six legs in place.

Going up - notice the ladder leg.

Builder sitting on construction seat setting leg - not a good job for folks with acrophobia!

Securing bolts with additional tower pieces ready to be installed. Note hoist rope powered by winch on ground.

Note use of platforms being used as movable stands while building tower.

Completing second thirteen-foot section with reference mark in foreground.

Typical horizontal control triangulation mark.

Mark truck with augur and cement mixer for digging holes and mixing and pouring concrete to set marks.

On the third thirteen-foot section.

Looking up the tower during construction.

Beginning construction of the cage (observer's platform).

Installing floor boards of the cage (observer's platform).

A 77-foot tower. The height is measured to the top of the inner tower used to support the observing instrument. The top of the outer tower was approximately 10 feet above this.

Tower at twilight. Note triangular boards at top of tower for supporting lightkeeper while showing lights to other stations.

Paraphernalia in an observer's truck. Note green case in bag containing Wild T- 3 theodolite. Batteries are for showing lights.

A Kern collimator for centering the observing tower over the mark.

Observer's equipment being hoisted to the top of the observer's platform.

Climbing a tower with a super.

Ron Ramsey observing with a Wild T-3 theodolite as seen from the lightkeeper's platform on the very top of the tower.

Ron Ramsey observing with a Wild T-3 theodolite.

Wild T-3 theodolite ready for observing. Chicago skyline in the background.

Objective lens of Wild T-3 theodolite.

Eyepieces for Wild T-3 theodolite. Larger lens was for observing. The smaller lens for reading horizontal and vertical angles.

Observing with Wild T-3 theodolite. Note centering plate secured to inner tower with C-clamps. This plate is directly above the survey mark on the ground below as determined by the collimator in image 1076. Ron Ramsey observer.

Ron Ramsey with Wild T-3 theodolite.

Monroe Rivers with Model 8 Geodimeter (electronic distance measuring instrument.)

Monroe Rivers with Model 8 Geodimeter (electronic distance measuring instrument ) . The Geodimeter is on a 4-foot wooden stand on top of a building.

Model 8 Geodimeter measuring distances from a rooftop in Chicago. Note the red dot to right of instrument. This is the laser-light return signal reflecting from a glass prism atop another building.

Operator control panel of Model 8 Geodimeter.

Hewlett-Packard Model 3800 electronic distance measuring device. Approximately 2-mile range.