Lovely old Ready Reckoner books - used to readily calculate discounts, measurements, conversions.... what a fab peice of the past these are.
Measuring:
Red "The Rapid Pocket Reckoner" - 14 x 8.5cm
Green "Collins Handy Ready Reckoner" - 14 x 8cm
Although I cannot find publishing dates, the green appears to be considerably older.
These are a great addition to your kitchen display- pop them in an old pudding bowl, in the top of some od scales or lay them open on an old bread board.