Tennis
2 of the 7 encyclopedias on this shelf carry an entry for Tennis. Both are reproduced below, so you can see where they agree and where they differ.
Aiton's Encyclopedia (1910)
a game of considerable antiquity. A similar game is known to have been played by the Greeks and by the Romans. The name is French, indicating that the game came into England by way of France. Tennis is played in a walled court ninety-six feet by thirty-two. A roof sloping inward surrounds the court on three sides to prevent the escape of the ball. The game was played at first with the open hand, in which it resembled the game of fives. Later the racket was introduced. A net five feet high is stretched across the court at its middle point . The player serves his ball against the wall or against the pent house, as the roof is called, in such a way that in the rebound it falls on the space beyond the net, where an opposing player stations himself to return it. The rules and method of counting credits are somewhat like those prevailing in lawn tennis . See Fives ; Lawn Tennis
Collier's New Encyclopedia (1921)
LAWN, an out-door game played with balls, which are of hollow rubber, covered with smooth white cloth, cemented to the ball, on a piece of smooth, level sward. It remotely resembles tennis. The players are separated from each other by a low net, stretching across the ground, over which they strike a tennis ball with rackets resembling tennis bats. The net should be 42 inches high at the sides of the court and 36 inches high in the middle. Each ball is two and a half inches in diameter and The weight of the weighs two ounces. racket may vary from 10 to 20 ounces. The modern game of lawn tennis was originated by Major Wingfield in Wales in 1874, and introduced into the United States the same year by F. R. Sears and James Dwight.