Editing Shuffling machine (section)

== Improving randomness using mechanical tricks ==
After 1930, inventors focused on the design of machines that could directly deal the cards, an idea that was already present in Ranney's machine in 1892. 

In 1932, a dealing table was patented by Laurens Hammond.<ref>{{US patent|1889729}}</ref> This was one of the first machines to use electricity to power the necessary shuffling and dealing mechanism. His patent description provides interesting insights regarding the problems related to previous machines: If the cards were worn or bent, the shuffling could fail. He also criticized the randomness of previous shuffling methods and pointed out the risk of predicting the final sequence. The patent also contains mathematical explanations regarding the inner state of his machine. A motor drove a rotating frame that would distribute 13 cards to each player. The machine went through 53 cycles to distribute the 52 cards. During each cycle, a selector plate with 52 notches rotated by one step. There were four possible depths for the notches and a lug touching the notches would determine which player would receive the card. Each card was taken from the top of deck and sent to the corresponding player's receptacle using a conveyor track. The first cycle was used to rotate the plate and ensured that the distribution would start with a new sequence. One property of the machine was that the same player could be served during two or three consecutive cycles. To increase randomness, the author proposes to use a set of different selector plates or to use another deck being shuffled while people are playing. The machine was fast enough to shuffle a whole deck in a few seconds. If only one plate was used, the same dealing sequence would appear after 52 deals (there were 52 possible starting points on the plate; the starting point was not randomly chosen, as the plate always rotated by one step in the same direction during each cycle).

The problem of ensuring randomness using mechanical means was hard to resolve. In the early 1930s, Robert McKay proposed an ingenious machine containing a chamber with 52 balls of different diameters (for each player, there were 13 balls with the same size).<ref>{{US patent|1992085}}</ref> Like in a [[lottery machine]], the balls would be shaken and randomly chosen by driving them one by one into a wheel with 52 slots. This wheel would then rotate, slot by slot, and a rod in contact with the ball would "detect" its diameter. A distribution mechanism could then use the diameter information and take the appropriate action to deal the card to the correct player.{{Citation needed|date=March 2023}}

Together with the lottery machines, the shuffling devices continued to evolve. In 1934, Ralph Potter invented an electromechanical machine that would read perforated cards and generates random sequences.<ref>{{US patent|2023210}}</ref> The data would be then used to power up lamps on the gaming table. These lights symbolized cards and roulette values. Players pressed on buttons to indicate their choices to the machine. To some extent, his device was one of the first attempts to make a computerized pseudo-random generator and game console.

During the rest of the 1930s, many inventions tried to address the dealing problem, mainly by using rotating frames that would distribute cards to each player around the table. Rotating parts were common in the shuffling machines; designers often used gears and plates with notches or holes whose purposes were similar to the sequence-generator plate of Hammond's machine. These shufflers shared some similarities with the machines used in [[cryptography]] such as [[Enigma machine|Enigma]]. This German encryption device used during [[World War II]] contained rotors that stepped each time a key was typed and produced an encrypted version of the letter. Both domains must fulfill mathematical requirements regarding randomness to avoid known patterns, repeated sequences and other kind of statistical weaknesses or biases.