Signedunsigned
FunctionThe three part device is designed to take ocean water temperature readings. A mercury thermometer records up to 10 hours of temperature readings; a battery-powered film recorder records readings onto a roll of film; a spring-driven brass clock mechanism times the film exposures, for example, one reading every 3 minutes for up to 10 hours. The waterproof cylindrical case is lowered into the ocean to gather data, then retrieved and film is developed.
Historical AttributesThe works of the deep sea thermograph consist of a photographic apparatus, lamp, batteries, films, clockwork, and thermometer.
The works were made by C. L. Berger and Sons of Roxbury, Massachusetts. Components, however, were made by specialized firms:
(1) The instrument was used with specialized thermometers by Henry J. Green of Brooklyn, NY. (They are described in the 1918 publication, but do not seem to be in the CHSI collection.)
(2) Small dry cells to power the electric lamp used in the photography had to be custom made. The zinc cans were made by Mr. V. Seitz at Cruft Laboratory, and they were filled and prepared by the Secret Service Battery Company of Everett, MA, through the kindness of Mr. F. D. Harper.
(3) The optical design of the photographic unit was devised by Professor Reginald Daly. The film used was 23 inches long. Temperature records on the film were about 0.1 inch apart and taken at 3-minute intervals over 10 hours.
(4) The clockwork unit was made by E. Howard Clock Company. It controlled the exposures taken on the film.
The works were enclosed in a water-tight steel shell called the flask. Thet flask was designed to withstand great external pressure. It was made of chrome-vanadium steel by the Hoffecker Company of Boston in a single forging. (The flask is not preserved at CHSI.)
The instrument was first tested in the laboratory and the Charles River.
Funding for the design and manufacture of the new device came from grants, specifically from the Bache Fund of the National Academy of Sciences with Professor Daly as the principal investigator. Daly also supplemented the funds with his own money and gifts from R. L. Agassiz, Livingston Davis, and G. B. Leighton.
Primary SourcesHarry Clark, "The Harvard Deep Sea Thermograph," Bulletin of the Museum of Comparative Zoology at Harvard College, 61, no. 15 (March 1918): 517-528, plus plates 1-5.