Good post and data, but if only things were so simple concerning the Meter's definition and the SOL it is fixed by. Unfortunately, the current definition of the Meter isn't 39.37 ins., but a host of trailing digits that skews things up considerably. The ratio of your differential using 39.37/39.375 is a 1/7874th. part, but the actual differential between the current Meter and the Old Meter is a 1/8024th. part. There is no reconciliation between the Current definition of the Meter and the old Imperial Metric system. And it is a common misconception that the current Meter is defined by the SOL. It is merely fixed to the SOL, as a figure that already existed prior to this definition. You rightly correlate Jim Wakefield's use of the Canonical unit 39.6 ins. as a good mediator of the Meter at 39.37 ins., but if your look at it again as the ratio 39.6 x 175/176 = 39.375 ins., things are better understood between the current definition of the Meter and the Old Meter. There is no simpler unit ratio of the definition of the SOL, than 300,000,000 OM's less a 1224th. part, or x 1224/1225 = 299,755,102 OM's.