58 On the Measurement of a Base on Epping Plains. 
Art. VIII.—Notes on the Measurement of a Base for the primary 
triangulation of the Eastern Section of the Coast of the United 
States, on Epping Plains, Maine; by A. D. Bacus, Superin- 
tendent U.S. Coast Survey.—With a Plate. 
{Communicated by authority of the Treasury Department to the American Associa- 
tion for the Advancement of Science. 
THE reconnoissance for a base of verification at the eastern 
extremity of the primary triangulation in Section I of the coast 
as commenced by Charles O. Boutelle, Esq., and Major Henry 
Prince, U. S. A., Assistants in the Coast Survey, in 18538 and 
continued through 1854 and 1855. The absence of long and 
Major Prince being relieved from the survey, the final minute — 
examination of the site and the determination of the best line 
which could be obtained on the plain, devolved upon Assistant 
Boutelle, who was assisted at different times by Sub-Assistant J. 
A. Sullivan, Lieut. J. C. Clark, U.S. A., and Mr. F. P. Webber. 
Epping Plains, or “ Barrens,” as they are called, lie betwee 
the Narraguagus and Pleasant rivers. They present a m 
rately rolling surface of sand, generally destitute of trees, except 
in the lower and swampy parts, and are traversed by sand midges” 
of different elevations, resembling very much the surface whicd — 
the sounding line develops, in such regions as the Nantucket 
shoals, at present below the surface of the water. 
The plain is quite elevated and falls suddenly from an irregt 
cats curved margin, by a steep slope to a lower plain or wide — 
Vv 
alley. 
_ Portions of the plain are strewed with boulders of various 
sizes, some of them containing not less than 4000 cubic feet, and 
of various granitic materials. Schoodiac Hill was found to limit 
the position of the base, so that the problem became to draw the” 
longest line through a point at the a of that hill, the ends of 
which would be easily visible from the secondary and primaly 
* 
stations. 
Before the final selection of the line a topographical survey — 
was made under the direction of Assistant C. O. Boutelle, bY 
