It is further expressly provided that this chapter does not apply to music machines; weighing machines; coin-operated machines or devices used by small children to receive rides thereupon, and which ordinarily are in the form of horses, fire engines, space machines, circuses and the like; any motion picture machine; any game of skill in which the direction and speed of the principal components of the game are manually controlled by the player, and where any mechanical operation in connection with the game is purely incidental thereto; and merchandise vending machines in which there is deposited an exact consideration and in which in every case the customer obtains that which he purchases. (Prior code § 22.7).