I liked this--from a 1942 opinion
The cabinets of said machines have a flat horizontal top in the shape of a table, mounted upon a base with one end of the table at a slightly lower elevation than the other.
The game is played on the top of said table by the use of a plunger which propels a metal ball to the top of said table from which point the ball rolls to the lower end.
The game is played by placing a nickel in a coin slot located on the lower left-hand corner of the table and by pushing the slot forward, whereupon a metal ball drops into a receptacle from which receptacle it may be elevated to the playing surface of the board by the player, so that the ball is in a channel which extends the length of the right-hand side of said table and directly in front of the plunger.
The ball is shot by pulling the plunger back along a scale, marked by degrees, and then releasing the plunger. The distance from the ball at which the plunger is released determines the speed which the ball will have when propelled from the channel onto the playing surface of the table.