Most measurements in this book are in imperial units given that this was the system used to design and operate the railways. The rulers or tapes then used would not be able to measure the fine tolerance required in modern engineering. There is a sense that the past is a foreign country, and the reader needs to make an effort to learn the idioms and currency used. To convert values calculated in imperial measures to metric with several decimal places disguises the design rules then in use and also gives a false impression of the accuracy required by the engineers of the day.

Inflation has made a mockery of simple conversions of Sterling to Decimal currency. For instance, Richard Speight’s annual salary of £3,000 equates to a very highly paid Chief Executive of the present day. Monetary values are therefore best appreciated by understanding the buying power of the money of the day, and some comparisons are provided throughout the text.

## Conversion Table

1 inch (1”) = 25 mm

1 foot (1 ft.) = 0.3 metres

1 yard (1 yd.) = 0.9 metres

1 chain (1 ch.) = 20 metres

1 mile = 1.6 kilometres

1 mile per hour (mph) = 1.6 kilometres per hour (kph)

1 pound (lb.) = 450 grams

1 ton = 1.02 metric tonnes