Craftsmanship at a glance
spirit level
Clockwise, from top: Mahoganynlevel with vial covers, levelnwith protractor, rosewood levelnand plumb bob, rosewood pocketnlevel, mahogany level with topnand butt plates, cherry level.

Spirit levels, the kind with the bubble in the vial, were first used by surveyors in the 1700's. It wasn't until 150 years later, however, that spirit levels were manufactured in sufficient quantity to supply general craftsmen. Before then, to make sure something was level, they relied on a version of the plumb bob.

The first levels were quite simple, with vials mounted in plain wooden stocks. However, the wood tended to warp slightly, or wear, and throw the level out of plumb. Eventually, tough, stable woods, such as beech, boxwood, cherry, and mahogany--even ebony and rosewood--proved more reliable. Finer levels were bound with brass top plates and butts. After 1860, set screws allowed adjustment.

Cast iron and iron filigree models first appeared after the Civil War, and conquered the warping problem. By 1940, mass-produced metal levels finally replaced the wooden level as the most popular.

Levels vary from pocket sizes, 2" to 5" long, to mason's and builder's levels of more than 10'. Unusual patent designs include those with 100° protractors; inclinometers; and combination level, plumb, and rule.

You'll pay for craftsmanship. Like sleek, imported sports cars, fine levels look expensive. Exotic woods, brass bindings, ornate cast iron and filigree stocks, and unusual designs bring highest prices.

Condition affects value, too. A level shouldn't show much wear. A maker's mark on the stock or stamped in the top plate also makes it worth more.

Levels represent a somewhat neglected area of collecting. You'll find most selling for $5 to $150. A very rare example may bring $1,000.

Photograph: Jim Elder