Robert Fletcher went to visit the canal in May 1913, during the latter part of construction. While there he saw a number of Dartmouth and Thayer alumni. Among them was Herbert Hinman (Dartmouth 1907, Thayer n1908) - in charge of the Balboa terminal work and earlier superintendent of work on the Pedro Miquel locks. Fletcher also mentions Otis Hovey (Dartmouth 1885) who designed and constructed the canal's emergency dams, and Fred Stanton (Dartmouth 1902, Thayer 1903).
Pictured here are several lithographs from Joseph Pennell's Pictures of the Panama Canal (Philadelphia, London: J.B. Lippincott Company, 1912) that depict places mentioned in Fletcher's diary or in letters from alums to Fletcher.
The Gatun locks appear in one of Fletcher's diary entries. "Langley met me and went over the Gatun Locks end to end and into some operating chambers in the middle wall. In the lower approach excavation 42 ft. below sea level." A postcard in Clarence Langley's (Dartmouth 1907, Thayer n1908) alumni file bears the inscription: "At Fort Lorenzo. Occupation - Transitman I.C.C. Address - Gatun, C.Z. Dear Prof. F. I answered your letter promptly...I do not intend to return to Hanover this Sept." I.C.C. stands for Isthmian Canal Commission, C.Z. for Canal Zone, and Prof. F. is Robert Fletcher.
Ask for Robert Fletcher's diary from 1913 (DA-4, Box 2234, folder 2) and the alumni files for the Thayer School (DA-4, filed by class year). The Pennell illustrations can be seen by asking for Illus P382pe.