The Colonial Era of Compass Making

There were very few instrument makers in America during the very early Colonial period, so most of the early surveying instruments came from England. In the Northeast, Americans started making surveying compasses out out wood. Outside of the Northeast, America stated making its own brass instruments as English trained instruments makers, like Anthony Lamb, started to immigrate to America. These immigrants brought with them the skills and approaches used in England, so the earliest American brass compasses tend to look like their English cousins, but with allowances made for the local American market.

The Circa 1730 Anthony Lamb Compass made in New York pictured below is a perfect example of a very early American brass Surveying Compass. [The Anthony Lamb Story is a wonderful story, and you can read about it here.] First, note how the compass face contains two sets of rings. These are typical graduations for compasses made in England, and the first American makers were trained in England or followed the characteristics of the English makers. The American market didn't value the inner ring much apparently, so almost all of the American made compasses featured a much cleaner design with only the outer ring divided. The existence of an inner ring oftentimes suggests that the compass was made in England or by a maker trained in England.

Second, note how the sight arms extending on the North and South ends of the compass are a rather thin bar. The British limited the import of brass into America, so brass was expensive and maybe even hard to source. Makers tended to economize on the use of brass before the Revolutionary War. After the War makers were more generous in their use of brass.

Third, note how the sight vanes attach to the compass - thru slide-on dovetails. This is a neat early feature, but was not very secure and led to a loss of sight vanes. Knurled Screws and pinned vane bases replaced the dovetail system over time. Dovetails were rarely used if at all after 1800.

Fourth, note the use of the wing bolts. That's another very early look. Thumbscrews replaced the wing bolts early on.

Fifth, if you look closely, you will see that East and West are reversed on the Lamb compass face. Reversing East and West made it easier for surveyors to track bearings. David Rittenhouse is sometimes given credit for reversing East & West, but the 1730 Lamb compass clearly proves that the reversal happened well before David Rittenhouse came of age. The reversing of East and West is actually discussed in Love's book "Geodaesia" (1688).

Finally, note the engraving on the compass face. Many of the early Colonial Compasses were simply engraved with some notable exceptions - like compasses made by Anthony Lamb.

The makers in the Northeast part of Colonial America typically made compasses out of wood rather than brass. Please take a look at the Wood Compass Webpage. Wood was probably far cheaper and easier to access than brass in the Northeast. And perhaps the surveys didn't require much in the way of accuracy (wood compasses with printed compass cards were typically less accurate than engraved brass compasses). Whatever there reasons, wood compasses were fairly popular in the Northeast, and were made there until roughly 1825 or so.

David Rittenhouse also invented the automatic needle lifter during the Colonial Era. This neat device saved wear and tear on the pin. The needle would only rest on the pin when the compass sat on top of a staff or tripod. See my dad's article cited above for a more detailed explanation.