SURVEY OF MASSACHUSETTS. 35. 
to this comparison, computed according to the Massachusetts scale, it was thought best to 
complete the calculations in the same manner, and make correction afterwards, when the 
proper standard should be fixed upon. For this standard, Hassler’s 82 inch Troughton, 
at the temperature 62° Fahr., was chosen. 
The apparatus with which the base was measured was constructed upon compensating 
principles, and was supported with a strong and firmly soldered tin tube between seven 
and eight inches in diameter, and, while in use, placed upon tressels properly contrived 
for carrying on such operations, a simple cross upon a plate of silver marking the termi- 
nus of the measure. The termination of each measure was observed with suitable com- 
pound microscopes, furnished with cross hairs, and supported upon stands conveniently 
contrived for such operations. 
The base line chosen for the Massachusetts survey was on the Connecticut river, above 
Northampton, and was found to be 39009.73 feet, or 7.3882 miles long. In addition to 
the information concerning its location, I have concluded to furnish, in a tabulated form, 
a comparison of its two measurements; the line having been twice measured. ‘The 
details are of course omitted. The termini of the base line were marked thus, ©, upon 
copper bolts of about three-fourths of an inch in diameter, which were driven firmly 
into holes drilled for the purpose in large stones, which were carefully imbedded in the 
earth about eighteen inches beneath the surface. The southern terminus of the base 
line is situated near the middle of a large field belonging to Josiah Ellis in the town 
of Hatfield, upon the west side of the Connecticut river. Its bearing and distance from 
the meeting-house in Hatfield village will probably be sufficiently well indicated by stating 
the latitude and longitude of each. 
: Latitude, Longitude. 
Hatfield Church, - - - - - = + = = = 42° 22’ 10” .97 72°06. 117.48 
Southern terminus of base line, - - - - = 42 222 21 .07 92 87 12 467. 
The northern terminus of the base line is situated in a lot of land upon the south bank 
of Bloody Brook, in the town of Deerfield. Its bearing and distance from the Bloody 
Brook meeting-house will be sufficiently well shown by comparing the latitudes and lon- 
gitudes of each. 
The latitude of Bloody Brook Church being 42° .29’ .04” .82 North. | Longitude 72° .36' 40” .78 West. 
a ‘* Northern terminus of base line, 42 .28 46 44 + 92 37 06 2S 
In measuring the base line we commenced from the north end; and at the end of 
every thousand feet we drove small plugs or piles of wood into the ground, and marked 
upon them, by means of a small brass wire driven into the top of each, the termina- 
tion of every thousand feet, as nearly as we conveniently could, without consuming 
toomuch time. We also left marks at the terminus of each day’s work. With such 
of these marks as we found undisturbed upon our second measurement, we compared 
our work. 
I would observe, that in making up the list of those comparisons, where the first mea- 
surement exceeds the second, I have marked the differences thus, +; and where the second 
measurement exceeds the first I have marked the differences thus, —. ‘The comparisons 
are Shown in the following table. 
