. Bulletin - United States National Museum. Science. Figure 79.—Surveying compass made by David Rittenhouse for Gen. George Washington, inscribed "Rittenhouse, ; This instrument was used by Washington in making a complete survey of his estate at Mount Vernon, 1796-1799. The survey was assisted by Capt. Samuel Duval, surveyor of Frederick County, Maryland. Washington gave the instrument to Captain Duval, from whom it descended to the Hon. Anthony Kimmel, who donated it to the National Museum. USNM 92538. In the Journal of Andrew Ellicott its author referred to this s
. Bulletin - United States National Museum. Science. Figure 79.—Surveying compass made by David Rittenhouse for Gen. George Washington, inscribed "Rittenhouse, ; This instrument was used by Washington in making a complete survey of his estate at Mount Vernon, 1796-1799. The survey was assisted by Capt. Samuel Duval, surveyor of Frederick County, Maryland. Washington gave the instrument to Captain Duval, from whom it descended to the Hon. Anthony Kimmel, who donated it to the National Museum. USNM 92538. In the Journal of Andrew Ellicott its author referred to this sector as follows: The boundary line to the North of Pennsylvania was fixed by Dr. Ritten- house and Captain Holland in the year 1774 and completed in 1786 and 1787. We commenced operations by running a guide line west from the point men- tioned on the Delaware 20^4 miles and there corrected by the following Zenith distances taken at its West termination by a most excellent sector con- structed and executed by Dr. Rittenhouse. The zenith sector is again mentioned in the appendix of the Journal: "One Zenith Sector of nearly six feet radius similar to the one made by Mr. [George] Graham for Dr. Bradley and Mr. Molyneux, with which the aberrations of the stars and mutation of the earth's axis were discovered, and the quantities ; Giftof Andrew Ellicott Douglass, Tucson, Ariz., in 1931. USNM 152078. Figure 11. Zenith Sector^ made of brass, original lens broken. Constructed by David Rittenhouse with some additions made by Andrew Ellicott. In The Journal of Andrew Ellicott the instrument is described as a— 145. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States National Museum; Smithsonian Institution; United States. Dept. of the Interior. Washington : Smithsonian Institution Pre
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