Make James Noble
Model Engineer's

1. This slide rule was used engineering calculations. On one face there was a "Routledge" type engineer's rule and on the other face a special slide rule for calculating the weights of steel.

2. The rule is folded at 188 since 1 ft of steel with a with a cross section of 188 mm2 weighs 0.1 lb. (304.8 mm * 188 mm2 * 17309 lb / m3 / 1E6 mm3/m3.)

3. The calculation is done by setting the width in (mm or 1/8") on the C scale against the thickness (in mm or 1/8") on the D scale. Against the length in feet on a A scale read the weight in pounds on the B scale.  This works for 1/8" and mm since 1/8" is 3.175 mm and 3.175 squared is 10.08.  If the values are entered in 1/8" the result is of course 10 times higher than if entered in mm.

4. The rule also has tables for  weights of materials and power of steam engines.

Front face
Back face
Detail - front right - showing scale folded at 5 and tables.

Detail - back right - showing scale folded at 1.88 and tables.


Manufacturing date Circa 1890.
Length 12 " (40 cm)
Material Boxwood
Scales Special on two faces
Cursor None