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 in- 

 strument 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. 



Telescope^ draw type, made of brass with acromatic lens, length 11 

 in. Incomplete, and maker not known. The second of the in- 

 struments described in The Journal of Andrew Ellicott as an acro- 

 matic telescope. Used for taking signals, with sliding tubes, which 

 draw out to about 15 in. It was considered to be remarkably 

 good for its length, and showed the satellites of Jupiter very 

 distinctly. 



Gift of Andrew Ellicott Douglass of Flagstaff, Ariz., in 1931. 

 USNM 152085. 



Transit and Equal Altitude Instrument^ made entirely of brass, 



with original lens now broken. The instrument is described by 



Ellicott in the following extract from The Journal of Andrew 



Ellicott: 



Preparatory to beginning the ten mile square [of Washington] a Meridian was 

 traced at Jones' Point on the West of the Potomac. From this Meridian an 

 angle of 45 degrees was laid off North Westerly and a straight line continued 

 in that direction ten miles. . . . From the termination of this second line a 

 third making a right angle with it was carried South-Easterly ten miles: 

 and from the beginning on Jones' Point a fourth was carried ten miles to the 

 termination of the third. These lines were measured with a chain which 

 was examined and corrected daily, and plumbed whenever the ground was 

 uneven, and traced with a transit and equal altitude instrument which I con- 

 structed and executed in 1789 and used in running the Western boundary of 

 the State of New York. This instrument was similar to that described by 

 Le Monnier in his preface to the French "Histoire Celeste." . . . All the 

 lines in this city in which I have been concerned were traced with the same 

 instrument which I used on the lines of the ten mile square but as the Northern 

 part was not finished when I left that place, I cannot pretend to say what 

 method has since been pursued. 



Deposit of Andrew Ellicott Douglass of Flagstaff, Ariz., in 1931. 

 USNM 152080. Figure 10. 



136 



