Invaluable for this study are Thomas Greenough's manuscript accounts that have survived in the collections of the Massachusetts Historical Society. The following itemized entries are selected from Greenough's business accounts over a period of two decades to provide data on the prices current in the second half of the 18th century for new instruments and for repairing others:
| In Account with Thomas James Gruchy: | |||
| 1754, April 27: | 1 Compass for the Schooner Sea Flour | £0.8.0. | |
| 1758, Nov. 28: | 1 Spyglass | £1.13.8. | |
| 1759, Jan. 25: | Mending 3 Compasses for the Schooner Susanna | £0.6.0. | |
| In Account with Nathaniel Bethune: | |||
| 1760, August: | A gauging rod | £0.6.0. | |
| Mending a telescope | £0.3.0. | ||
| In Account with Captain McAndrew Mirick of Nantucket: | |||
| 1772, March 21: | For 2 compasses, 1 leaded | £0.16.8. | |
| In Account with Captain Roberson Crockett: | |||
| 1773, April: | For mending 2 Compasses | £0.6.2. | |
| For mending 1 Hanging Compass | £0.3.2. | ||
| In Account with Captain Reworth of the Brig Fortune: | |||
| 1774, March 30: | For mending 2 compasses & Glasses | £0.7.0. | |
| In Account with Captain Thomas Godfrey: | |||
| 1774, April 7: | For 1 Telescope | £0.8.0. | |
Other documents in the same collection indicate that Greenough's business interests were substantial and not limited merely to the construction of instruments. On July 31, 1769, Greenough's name appeared on the Boston Citizens' Non-Importation Agreement. Subsequently, on December 14, 1774, there is Greenough's signed receipt, with the amount left blank, stating that he had "REC'D. of Capt. Thomas Godfrey the Sum of —— in full for my Negro man Cuffes Shair in the Whaling Voige ——."
Figure 42.—Brass surveying compass made by Thomas Greenough (1710-1785) of Boston. Compass face is mounted on main blade with two copper rivets. Screws for vanes and tripod mounting are hand cut, with wing nut ends. Sighting bars are 1/16 in. wide and 5-1/4 in. high; over-all length is 11-7/8 in. and diameter is 5-1/4 in. Owned by Greenough family of Boston. Photo courtesy of Dr. Thomas Greenough.
Greenough apparently was succeeded in business by his son William Greenough. Mr. Lawrence B. Romaine of Middleboro, Massachusetts, in 1939 described a wooden surveying compass with its own hand-whittled tripod made of oak which bore a compass card inscribed "Made by William Greenough, Boston, N.E."[94] The compass was protected by a pine cover that fitted closely between the sights. The present location of this instrument is not known, but it appears to be the only known example by William Greenough made of wood.[95]
Figure 43.—Wooden surveying compass, made and sold by Thomas Greenough. The instrument is made of gumwood and has a paper compass card; it is 13-1/4 in. long and has a diameter of 5-3/4 in. In collection of Franklin Institute, Philadelphia.
In the Greenough family at the present time is a brass surveying compass (fig. 42) of fine quality and of the period before or during the American Revolution. The dial is finely engraved with a Tudor rose at its center, and around it is the inscription "Thomas Greenough Boston Fecit." The compass face is mounted to the main blade with two copper rivets. The holding screws for the vane and tripod mounting are rather crudely hand cut with wing-nut ends.[96]