_Quadrant_ of brass made and used by Ellicott. Quadrant has a radius of 12 in., is on a stand 17 in. high, and has the original lenses. Simple construction with easy adjustment, accomplished by means of two plumb lines. A tangent screw for slow motions was designed and added in 1885 by Andrew Ellicott Douglass, Ellicott's grandson. Instrument was made by Ellicott about 1790 and was used in running the southern boundary of the United States in 1796 and 1800, and on other surveys. Deposit of Andrew Ellicott Douglass of Tucson, Ariz., in 1931. USNM 152081. FIGURE 72. _Surveying Instrument_, with brass disk 10-1/2 in. in diameter laid off in degrees, minutes, and seconds with vernier points. Two telescopes, one fixed and the other revolving. The instrument is mounted on a tripod or Jacob's staff by means of a socket on the underside. Complete with original painted pine case. The name of the maker, "G. Adams London," is engraved on the dial. George Adams (1704-1773) was mathematical instrument maker to King George III. After serving an apprenticeship from 1718, he made instruments for the East India Company in 1735 and 1736, and established a shop at "Tycho Brahe's Head" at the corner of Raquet Court, Fleet Street. He specialized in terrestrial and celestial globes and microscopes. Following his death he was succeeded in business by his son George Adams the Younger (1750-1795), who also served as mathematical-instrument maker to the king. This instrument is believed by the donor to have been used by either Andrew Ellicott or by his son-in-law David Bates Douglass. Gift of Charles B. Curtis of Litchfield, Conn., in 1945. USNM 312932. [Illustration: Figure 72.--Brass quadrant made by Andrew Ellicott about 1790 and used for running the southern boundary of the United States about 1796 and 1800, and on later surveys. USNM 152081.] _Telescope_, consisting of a brass tube 3-1/2 in. long with an aperture of 2-3/4 in.; on its original brass tripod, with a serviceable altazimuth mounting. Late 18th century. Made by "W. & S. Jones/135 Holborn/London." The firm of "W. & S. Jones" was a partnership of two brothers, Samuel and William Jones, opticians, who worked at 30 Lower Holborn and at 135 Holborn in London, from 1793. They bought the copyright to the books of George Adams, and subsequently largely carried on the original business of the Adams instrument makers. In _The Journal of Andrew Ellicott_ its author describes this instrument as the first of "Two Acromatic Telescopes for Taking signals, with sliding tubes, one of them drew out to upwards of 4 feet, and the other to about 15 inches, the latter for its length is remarkably good, it shows the satellites of Jupiter very distinctly." Deposit of Andrew Ellicott Douglass of Tucson, Ariz., in 1899. USNM 152082. FIGURE 73.