The ternary calculating machine of Thomas Fowler  
Fowler's binary and ternary tables About
the machine 
Fowler's ternary calculating machine  the product The product is a series of sliding rods, held on a raised platform at the other end of the machine from the multiplicand. They have teeth that extend below the platform to engage the corresponding teeth on the ends of the multiplier rods. As the ladderlike frame of the multiplier is rotated, pushing the multiplier rods one direction or the other, the product rods are pushed accordingly to represent the value of the result. The initial position of the product rods is set to the middle of the platform, corresponding to a value of zero. The rotation of the ladderlike frame of the multiplier pushes or pulls any multiplier rods not set to zero. As a result, the teeth at the end of those multiplier rods engage the corresponding product rod, sliding it by one unit in either direction. As the calculation progresses, an individual product rod may be pushed more than one unit, causing an overflow in that digit. The platform supporting the product rods allows for an overflow of three units before the carry mechanism must be employed, bringing that digit back into the allowable range of “+”,“0” or “”.



