Norman White weird conversion numbers.

I was reading a bit in Mr White´s new book, the gear box chapter. I´m having proper oil seals put in for the shafts in the outer cover by a friend who has a lathe so I was writing all the numbers down. Be careful if you are doing this and using the advice's in this book, there are some strange conversions from inches to mm. Mainly the diameters for the seals, the kick shaft diameter is converted from 0.998" to 24 mm in the book, the real number is 25.34 mm. a big difference. The same for the gear shaft, 0.750" is converted to 20 mm, when it in fact is 19.05 mm. This is of course no real problem, because I guess everybody buys the correct seals and take the measurements from them before machining, just think it´s a bit odd. Makes you wonder if there´s more things like this to look out for.