Constructed of aluminium the Stephens Supremathic is an unusual implementation of a logarithmic circular slide rule. The central knob allows the inner wheel bearing the cursor to be rotated clockwise to its zero position, or forward in an anti-clockwise direction. The outer wheel bearing the other logarithmic scale can rotated separately at its perimeter and unless the cursor is held, rotates the cursor with it. The front wheels are used for multiplication and division.
To multiply a number you first set that number at the top outer hairline, then set the zero of the cursor to the same point, and finally rotate the zero point counterclockwise to the multiplier. The result is read under the top hairline of the outer wheel.
On the back are five scales fixed to the reverse of the larger wheel and showing through five corresponding windows, and show respectively the log, sine, tan, square and cube of the reference number which is dialled up under the top hairline of the outer wheel.
The Supremathic is also equipped with centimetre linear ruler and right angle pull out arm.
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