Tower with signal flag at Station Bint. At Bihintinusa Island off the south coast of Basilan. Built by crew off the MARINDUQUE

Station Mangal from offshore. Built by crew off the MARINDUQUE

Building crew after finishing the tower. Party off the MARINDUQUE

Building a tower. Party off the MARINDUQUE

The finished tower - note guard in lower left of tower. Party off the MARINDUQUE

A finished large tripod signal - note the guards. Party off the MARINDUQUE

115-foot tower built around tree on Sarangani Island.

Another view of tower built around a tree on Sarangani Island

Small tower on a coral islet

Tower with signal

239-foot tower built on Bugsuk Island in southwest Philippines. This tower was built completely from native timber cut on location. It took 19 men off the PATHFINDER three weeks to build this signal. This was the largest wooden tower ever built by the C&GS. Used for both observing and as a signal

Using a day marker as a tower. Photo#1 of sequence

Observing angles from the top of the day marker. Photo#2 of sequence

Tower built around tree in the Philippine jungle.

Triangulation station built in shoal water. Combined operations party of Hubert A. Paton

Tower built around a tree trunk.

Station Plainview in eastern Montana. Triangulation party of Wilbur Porter

Station Cook - tower had to be built after error by reconnaissance man. Triangulation party of Wilbur Porter

Hecht was the observer at this station in North Dakota. Small wooden observing stand. Triangulation party of Wilbur Porter

103-foot light stand at Station Red Cloud.

Climbing a small tower at Station Pinnacle. Providing horizontal control survey for aerial photography of King County

Pole tower built from native timber at Takhini West Base. Note signal flag on tree. Triangulation party of F. B. Quinn

Tower at Station Indian covered with ice and frost. Station is just below the Arctic Circle. Triangulation party of Walter R. Helm

Small wooden stand on ridge in Mojave Desert. Station built during observations on Transcontinental Traverse work. Triangulation party of Woodrow Johnson

Early steel gas pipe tower built by the Lake Survey.

The first picture of a Bilby portable steel tower under construction. Bilby towers were made of prefabricated steel parts that could be reused. These towers were designed by Jasper Bilby, chief signalman of the C&GS

The first picture of a completed Bilby tower. Bilby towers were made of prefabricated steel parts that could be reused. These towers were designed by Jasper Bilby, chief signalman of the C&GS

Using Bilby towers for hydrographic signal on the Florida coast. Built by party off of HYDROGRAPHER

Bonita tower in southwest Florida. Traverse party measuring distance in foreground. Party off of HYDROGRAPHER

A 90-foot Bilby tower wrecked by a storm. Triangulation party of Earl O. Heaton

Tower at Station Schnackenburg.

Building Station Reid. Triangulation party of Paul A. Smith

Power source for hoisting steel. Jack up truck and use "fifth wheel". This could be dangerous - at least one leg broken by getting wrapped up. Safety modifications made to system after individual severely injured. Triangulation party of Paul A. Smith

Preparing to dismantle Station Village Mills South Base. Triangulation party of Paul A. Smith

Climbing the tower at Station Walting. On the Ohio-Indiana boundary. Triangulation party of H. C. Warwick

Straightening steel - even the portable towers needed some maintenance. Triangulation party of C. D. Meaney

A study in geometry - looking up a Bilby tower. Station South Bend, Louisiana. Triangulation Party of Eugene R. McCarthy

50-foot Bilby tower in Nebraska or Montana. Triangulation party of Wilbur Porter

Looking down from the top of a 50-foot tower. Triangulation party of Wilbur Porter

Looking up the side of a 50-foot tower. Triangulation party of Wilbur Porter

Tower with observing tent to shield the instrument from the wind. Triangulation party of Wilbur Porter

Tower at Station Bowie.

Collimating the inner tower at Station Winnie. Collimation involved placing the observing instrument directly over the mark. Triangulation party of Carl I. Aslakson

Lightkeeper orienting lights for distant observers. Tower at Station Northome. Osborne at lights, Caouette recording, Tryon at tent. Triangulation party of Carl I. Aslakson

Tower at Station Eufaula.

Tower at Station Northome. Caouette on left, Osborn on right, Tryon observing. Triangulation party of Carl I. Aslakson

Tower at Station Winnie next to firetower. Triangulation party of Carl I. Aslakson

Photos # 5-7 show stages in completing a 50-foot tower at Station Tatum. Photo #8 shows theodolite being transported to top of tower. Triangulation party of Wilbur Porter. Photos # 5-8 of sequence

Station Weingard near Amarillo. Triangulation party of Wilbur Porter

Photos #1-4 show beginning of construction of 50-foot tower at Station Tatum. Triangulation party of Wilbur Porter. Photos 1-4 of sequence