The standard Mitchell is set up and an even number of sets of boards are placed on a relay at the end of the movement (or for that matter anywhere in the movement). For example, in a 5 table Mitchell (with 2 extra sets to make a 28 board movement) set 1 (boards 1-4) is placed on table 1, set 2 (5-8) on table 2, ...set 5 (17-20) on table 5, and set 6 (21-24) and 7 (25-28) on the relay. The move is exactly the same as a standard Mitchell, N-S stationary, E-W up 1 table and the boards down 1 table, moving through the relay after table 1.
Unfortunately there is always one special move round. With 2 sets on the relay, the E-W pairs on the ultimate round find the table to move to by subtracting their pair number from N+1(where N= number of tables in the movement). The boards still move normally.
With 4 sets on the relay, they subtract their pair number from N to find their seats on the penultimate round and then move normally (up 1) into the last round. With 6 sets, subtract their pair number from N-1 for the table on the ante-penultimate round, and then return to normal, moving up 1.
When the E-W pairs subtract their pair number from N, for one pair (highest numbered pair) zero is the answer; they must subtract their number from 2N. In the N-1 case, for two pairs (N and N-1) the answer is less than 1. They then subtract from 2N-l. These pairs should be given their instructions separately before or after general announcement.
In the example given above for 5 tables, the E-W pairs will be instructed to subtract their pair number from 6 to find the table at which to sit on the last round.
This extra board movement supplies us with a Mitchell for 3½ tables. The movement is set up with three standard tables plus four extra board sets at the end so that there are 7 sets of boards in play. As there are seven pairs, a rover movement can be used and each pair can sit out for one set. Original N-S pairs are numbered 1,2 and 3; the E-W pairs 4,5 and 6; the rover pair number is 7. A switch is needed at the 6th round, but as this is the round of subtracting their pair number from 3 (pair number minus 3 for E-W i.e. 6 minus pair number) to get their table numbers, the pairs can also be asked to change directions at the tables. The N-S pairs are stationary throughout (except for the switch round) and the E-W move up 1. The rover pair sits out on the first round. They then go to table 1 replacing N-S pair 1 on round 2, and E-W pair 5 on round 3. Then goes to table 2 replacing N-S pair 2 on round 4 and E-W pair 4 on round 5. Then to table 3 (after the switch has been called) replacing the N-S pair 6 on round 6 and E-W pair 3 on the last round.
A similar movement is available for 5½ table Mitchell with 11 rounds (i.e. 2-board sit-out).
Six relay sets are placed after the last table. E-W up 1 and boards down 1, through the relay. Pair 11 is a rover.
