Abraham Lincoln, William McKinley and John F. Kennedy were the prime rockers of the their day - all three presidents were devoted to their rocking chairs.

Lincoln had one in his box at Ford's Theater, courtesy of the management; McKinley campaigned from a wicker rocker on his porch; and Kennedy found it eased his aching back.Popular folklore credits Benjamin Franklin with the invention of the rocking chair, but actually it precedes him. Rocking chairs have been traced back to the 1740s through the wills of American colonists.

Even though rocking cradles had nestled infants since 1000 A.D., it was another 700 years before anyone thought of placing curved runners on chairs. That may be because it was not until about 1700 that the technology developed that was necessary for widespread chair production.

Within a matter of years, word spread up and down the Eastern seaboard as cabinetmakers attached runners to standard chairs. By 1800s, rockers were an industry of their own.

Thrifty Americans were not about to discard their old chairs - often they had cabinet makers attach runners to old pieces. it is often difficult to distinguish between a chair-rocker and a true rocking chair, for both may have similar runners.

The converted chair's legs often show evidence of having been cut down.

Before 1815, most runners extended the same distance in front and back. As the rocking chair grew older, the runner grew longer in back and shorter in front - another clue in determining age.

The Boston rocker, the kind Kennedy favored, was the most prevalent style, but the early rocking chair was actually a form of the Windsor chair.

Other designs popular with American cabinetmakers were the Hitchcock, Shaker, Sheraton, Bamboo and early Victorian.

One Dr. Calvert recommended armless rockers for "invalids and the weaker sex," and "Dr. Calvert's Digestive Chair" helped introduce rocking to thousands of Americans in the mid-1800s. This armless model still is named for the person or task it was intended to aid - sewing rocker, nursing rocker, ladies' rocker.

The platform rocker with buggy seat springs was to stop rockers from inching across a room, and about 1860 Michael Thonet discovered a way to bend wood that led to the bentwood rocker.

At Ford's Theater in Washington, the manager learned of Lincoln's preference for rockers and pulled one from storage. With its scrolled arms and S-curve upholstered back, it became known as the Lincoln rocker after his death.

Rockers remain a staple for antiques dealers and new furniture shops because of their charm and comfort.

As an English traveler reported in 1838: "In America, it is considerd a compliment to give the stranger the rocking chair as a seat; and when there is more than one kind in the house, the stranger is always presented with the best."