In British practice the length of the slate is typically twice the width, each of the most popular sizes having a traditional name. Thus Imperial slate sizes range from 12″ length by 6″ width (Small Doubles) and 14″ by 7″ (Narrow Ladies) up to 24″ by 12″ (Duchesses) and 24″ by 14″ (Princesses). Popular sizes are:
Duchesses: 24″ x 12″
Small Duchesses: 22″ x 12″
Wide Countesses: 20″ x 12″
Countesses: 20″ x 10″
Wide Viscountesses: 18″ x 10″
Viscountesses: 18″ x 9″
Wide Ladies: 16″ x 10″
Ladies: 16″ x 8″
Clearly when modelling it is necessary to assess the type of slates used on the building in question and allow for the overlap which takes up a lot of the length.
The N Gauge table is:
| Size | Length (inches) |
Width
(inches)
|
N Gauge
Length (mm)
|
N Gauge
Width (mm)
|
| Duchesses | 24 | 12 | 4.1 | 2.1 |
| Small Duchesses | 22 | 12 | 3.8 | 2.1 |
| Wide Countesses | 20 | 12 | 3.4 | 2.1 |
| Countesses | 20 | 10 | 3.4 | 1.7 |
| Wide Viscountesses | 18 | 10 | 3.1 | 1.7 |
| Viscountesses | 18 | 9 | 3.1 | 1.5 |
| Wide Ladies | 16 | 10 | 2.7 | 1.7 |
| Ladies | 16 | 8 | 2.7 | 1.4 |
Information from John Williams Roofing.
