Slide rules HOME page COLLECTION NON-STANDARD RULES
Make Lorkin, London
Model Soho rule
1. This rule was designed for ship's mast. As far as I can tell, not being an expert in 18th century mast design, The main difference between this and a "standard" Coggeshall rule is the inclusion of formulae for mast design.
2. The formula given differ from, and are simpler than, those in "The sea-man's vade mecum of 1707".
http://www.bruzelius.info/Nautica/Rigging/Masting/Vademecum(1707)_p131.html
3. For example, on the rule the fore mast is given as 9/10 of the Main Mast. In the Vade Mecum the method takes account of the configuration of the deck but allows for it to be standing 1 yard below the main mast.
4. As the table includes reference to the gun deck, this was probably for naval ships.
5. For a diagram of a ship's mast click here.

This rule is from the collection of M Taylor.

Front view
020-lorkin-01

Detail front left
020-lorkin-01

Detail front right
020-lorkin-03

Back view
020-lorkin-04.jpg (20775 bytes)

Detail - back
020-lorkin-05.jpg
Manufacturing date Lorkin operated from 1789 to 1830
Length 12"
Material Boxwood and brass
Scales See above
Cursor None