The history books tell us that ‘North Star’ was one of two engines, originally built by Stephenson’s for the 5’ 6” gauge New Orleans railway. That order was cancelled and these engines – works nos.149 and150 - were snapped up by the GWR, desperately in need of reliable engines.

Several changes were needed to adapt these engines to Brunel’s 7 foot gauge. A sketch showing these changes was made in 1837, as shown below:

Copy of original drawing of Stephenson engines nos. 149 and 150

The first delivery (actually works no.150), was made by barge to Maidenhead on 28th November 1837. This was the famous ‘North Star’

Some modifications to the firebox were requested by Brunel for the second engine, named ‘Morning Star’, which retained its original 6’ 6” diameter driving wheels and had the safety valves in a single casing behind the dome. Apparently a drawing was made by E.T.Lane but Arman, in his book: 'The Broad Gauge Engines of the GWR, Part One', considered it too faint for publication.

I have not seen this drawing so have had to use the later version produced by G.F.Bird for the Locomotive Magazine in 1901. On past experience, I have some scepticism concerning the accuracy of these drawings but a comparison of the dimensions with my model of North Star showed that they were very similar.

Drawing by G.F.Bird for the Locomotive Magazine in 1901

On the assumption that all the major components were the same, I had to do very little work to alter my 3D model of ‘North Star’ to the appearance of ‘Morning Star’

I re-scaled the wheels and splashers by 93% in the X and Z directions, deleted the two safety valve covers, and created a new single cover by my usual method of applying the ‘revolve’ tool to a sketch of the profile.

The result was is shown below:

My model of ‘Morning Star’, adapted from ‘North Star’

When I first looked at that 1837 drawing of the modifications, I was confused by the overlapping of the plan and elevation. For a few moments I thought that the ends of the axles were the safety valve covers on North Star! Could a young draftsman have thought the same?

Mike