2. In this rule I, unfortunately, had the slides on the wrong faces of the rule when I scanned it. In reality the front of the rule would have had the "classic" A, B, C (2-cycle) and D (1-cycle) scales. The sine and tan scales would have been between the two A (2-cycle scales)
3. The combination of A, Sin, Tan and A scales would cover the range 0.6º to 45º for the tan scale and 0.6º to 90º for the sine scale. It would have been possible to do simple calculations using the trigonometrical scales without a cursor.
4. Some of the "gauge points" seem a bit strange. (In fact they are not gauge points but settings of the rule to get a factor similar to the use of 22 and 7 for pi). For example, using 81 gallons to 13 cubic feet gives a ratio of 6.23 whereas 25 gallons and 4 cubic feet gives the exact value of 6.25. It could not have been due to the use of either the wine or ale gallon as both of these had a larger difference the between 62.5 and 62.3.
5. The maker, Elliot, was at the address shown in London in from 1840. Given that fact it is interesting that the rule refers to Wine gallons some 16 years after they became obsolete.
This rule is from the collection M Taylor.
Front view
Detail front left
Detail front right
Detail back
Detail - back left
Detail - back right
Detail - maker's name
Detail conversion
Detail - Chord scale
