Borden Baseline

Notes on the survey baseline for the first accurate map of Massachusetts.

In the 1830s - 175 years ago - a group of extraordinary men began the survey of Massachusetts, using advanced mathematics and scientific principles. The survey began in the Connecticut River Valley with the “Borden Baseline” - a precisely measured line on the ground almost 7 1/2 miles long. The north-south line stretched from Deerfield to Hatfield. Once the surveyors measured this baseline with great accuracy, they would measure distances to nearby mountaintops using trigonometry, and could then extend their measurements all across the state. The survey took several years but when they were done the state was mapped with great accuracy.

Surprisingly, the southerly terminus of the Borden Baseline still exists - a boulder with a copper plug in the backyard of a house in Hatfield.

The monument still exists today, The copper is the greenish

circle in the center with a cross

cut into it. The shiny circle is a 25c coin for perspective. The stone is in the backyard of the house at 30 Bridge Street in Hatfield, nowowned by Dan and Sue Edwards. It is not known if this is the origoinal position of the bolt, as the ground has been re-worked.

The map on the left is an excerpt from the 1844 map of Massachusetts by Simeon Borden. The triangle labelled “S. End of Base” is the copper bolt still extant on Bridge Street in Hatfield. On the right is a modern map showing the old location of the baseline. The broad, level Connecticut River Valley was an ideal location for a long survey baseline. See also the more detailed USGS map on the next page.

The survey of Massachusetts took ten years to complete. Most of the work was the careful, methodical transferring of coordinates to each of the 250?? towns across the length a breadth of the state. The results were drawn onto a large state map which was published in 1844. The work was commissioned by an act of the state legislature on March 3, 1830.

The actual surveying of the baseline took place in the summer and fall of 1831. The location for the line was selected in 1830 by James Stevens, supervisor of the project. Borden reports, (in his 1841 talk to the American Phili\osophical Society in Philadelphia (published in 1846 in Transactions, Vol.IX, New Series, Article II)), that “...in the ensuing winter I made the measuring apparatus and made...repairs in the instruments...”. In late apring, the equipment was shipped to the base line where Stevens made preparations until June, when Borden joined him. We presume that sometime that sporing the actual monuments were set for the baseline.: ”copper bolts of about three-fourths of an inch in diameter...driven firmly into holes drilled..in large

stones which were carefully imbedded in the earth about eighteen inches beneath the surface. “the southerly

terminus of the base line is situated near the middle of a large field belonging to Joseph Ellis in the town of Hatfield, upon the west side of the Connecticut River.” The full text , which is incl;uded in these notes, goes on to describe the precise methods the surveyors used that summer and fall to measure the exact distance between the two points. The measurements were made with a 50 foot long rod which was carefully suspended on wooden trestles. The rod was made of metal, and was encased in a tube to limit the effects of temperature on the rod’s length. Great care was taken to keep this rod on a straight line and to compensate for slope changes (???) as they measured. When they were done with the computations, Borden calculated the length of ths 7 1/2 mile long line to one-hundreth of a foot (about 1/8”). The distance was 39,009.73’ (7.388 miles). Eight men were needed to survey this line .

Excerpts from an 1841 talk by Simeon Borden, describing part of the surveying methods for the Borden Baseline. In the first paragraph above he describes “copper bolts of 3/4” in diameter... driven firmly into holes drilled ..in large stones...carefully embedded in the earth about 18” below the surface”

Map of the triangulation network for the survey of Massachsetts. (see enlarged section below)

The Borden Baseline is the short vertical line at the center of this map excerpt. From this 7 1/2 mile long line precise angles were measured to nearby hilltops, thus measuring their locations precisely, and allowing the rest of the state to be accurately over the next several years.

Borden’s mapping project resulted in a large state map, published in 1844. All major roads and town centers were drawn on the map with great accuracy, while smaller roads were drawn in based on maps supplied by the various towns.