Grade Conversions

[Graham Fry <fryg@sydpcug.org.au>]

As a die-hard steam nut I am reading the best steam book I have ever
found on steam - David Wardale's "The Red Devil and Other Tales from the
Age of Steam". This book is all about his projects to increase the
efficiency and reliability of South African steam by using a lot of the
principles and theories of the South American steam engineer LD Porta.
The book is over 500 pages of technical info, drawings, tables with only
minimal photos - wonderful. However, he constantly refers to grades in
percentages. Can someone provide me with the conversion to our method of
defining grades in 1 in ??. Thanks in advance.

Graham Fry