An Ancient Joinery Technique
The technique of cutting and carving dovetails to join wood dates back to ancient Egypt, but it became especially popular as a substitute for nailed joints in the late 1600s in Europe. The dovetail joint consists of interlocking pins and tails that are angled to resemble a dove's tail -- the pins are usually smaller than the tails. The pins and tails fit together tightly and, when crafted by a skilled woodworker, hold boards together securely without the need for other fasteners. Artisans use this joint to fashion cabinets, tables and other furniture, but one of its most important uses is to fashion drawers and other boxes.
Hand-Cut Imperfection
In the early part of the 19th century, all dovetail joints in European and American furniture were done by hand, using a saw and chisel. As useful as these joints are, they are difficult to cut and carve, and many artisans saved time by making just enough pins to make the joint effective. The pins are usually irregular, may be large or small, and may be angled up or down with respect to the edge of the joint. These imperfections persist on furniture made throughout the 19th century, although furniture made in America toward the end of the century begins to show signs of standardization.
The Knapp Joint
Because cutting dovetails by hand is so time-consuming, modern furniture-makers almost always use a jig to measure and cut dovetails, so even handmade furniture features highly regular pins and tails. This trend began in 1870 with the development of the Knapp joint, also called the pin and cove joint. This somewhat complicated joint could be produced on a machine, and it featured rounded pins and dowels to secure the pin to the tail. It wasn't -- strictly speaking -- a dovetail joint, but it was attractive and secure and could be done quickly. It's a feature of American furniture produced from 1870 to 1910, especially drawers.
Machines Take Over
The first machines that could cut dovetails were powered by steam, and they appeared in the last decade of the 19th century. From this time until the present, cutting dovetails has largely been the purview of machines -- at least in North America. European artisans continued to cut dovetails by hand well into the 1900s. Machines are capable of more precision and regularity than is possible with hand tools; dovetails in most 20th-century furniture are all the same size and perfectly formed. They are often square, which technically makes them finger joints, not dovetail joints. You won't see any of the chips and gouges that hand saws and chisels produce.