In the early part of the period, nail-makers cut them by hand from a sheet of iron.
Later, machine did the cutting, but nails were still made one at a time.
Iron ore and carbon heated together and then cooled created wrought iron, from which a nail length piece was cut and hammered on four sides to create a point.
Hand-wrought nails have tapered but irregular and crooked square shafts.
The wood fibres would often swell if damp and bind round the nail making an extremely strong fixing.
In Tudor times, we have evidence that the nail shape had not changed at all as can be seen by the nails found preserved in a barrel of tar on board the 'Mary Rose' - the Tudor flag ship of Henry VIII built in 1509 and recovered from the mud of the Solent in 1982.
Manual of the American Railway Engineering Association. 2 American Railway Engineering Association, Specifications for Dating Nails, 1931.
When dating a piece of antique furniture, one of the most important clues to its history is often overlooked.
A nail may not be a noticeable style feature, but looking at them carefully can help you authenticate the age of a primitive or antique furniture piece before you buy.
Wherever treated ties come into use, date nails are not far behind.
Railroads need a way to monitor their investment in treating, and date nails became the most common method of this record keeping.