Received this by email I have in my possession a Chesterman 24 inch steel ruler but upon comparing it against a tape measure I find that it is only 23 inches and the metric scale showing 61 cm is actually 59 cms. It appears to be rather old and I cannot understand why there would be a difference between the readings. Could it be that it was made like this for a specific reason and if so can you supply an answer to this puzzle? Many thanks Rod Allen