I’ve referred before to the problems that arise from using published drawings as the basis for creating 3D models of early locomotives. The usual dictum of “find a photograph of your selected prototype” simply doesn’t apply to the years before photography became established.

 

That leads to the next problem – so much of the information we read about early locomotives comes from books that were written decades after the time to which they refer. Even Gooch’s own ‘diary’ is considered suspect, since the pages about the early years were clearly written much later. It’s by no means a new problem either – Sekon, in his book ‘The Evolution of the Steam Locomotive’, published in 1898, made the following comment: “Readers may wonder why such obviously inaccurate statements should be published. One can only conjecture. Many lists of early locomotives have during the past few years been published. These should, however, be accepted with the very greatest caution.”. Matters have got considerably worse with the passage of much more time!

 

We are very fortunate to have the sketch books and drawings made by the young apprentice at Swindon in the 1840s, Edward Lane, who sadly died at the age of 20. In his short life, he made an invaluable record for posterity of first-hand views of early Broad Gauge locomotives and other rolling stock. Even though many of his illustration are only rough sketches, they present a ‘from life’ impression and many of them are annotated with measurements and additional sketches of small details.

 

Much later, early in the 20th century, another set of illustrations was produced by G.F. Bird and these appeared in a special supplement to ‘The Engineer’ magazine. Later still, after WW2, the RCTS produced a booklet covering the Broad Gauge Engines of the GWR as Part Two of a series on GWR Locomotives. On page B3, the booklet comments that “Bird's line drawings, the early ones mainly derived from the sketches and drawings made by E. T. Lane at Swindon in 1848/9, still remain a classic. They are the only known illustrations of many of the early engines and some are used yet again in this volume”. We must not, however, forget the caution sounded by Sekon back in 1892 and, from my own experience, Bird appears to have misinterpreted some of the information contained in Lane’s sketches.

 

In replying to comment in my previous post about Leo-class engines, I wrote that “Another example I have found is the case of 'Evening Star', where Lane shows appropriate-looking safety valve covers but with figures above them that seem to indicate a much larger diameter. Bird has drawn extremely fat covers, presumably based on his reading but, to me, they do not look 'right'.”

 

Comparison of sketch by Lane and later drawing by Bird

 

I reported that “One day, I must study this engine in more detail”, so here goes!

Modelling ‘Evening Star’

 

In the case of the ‘Stars’, we are especially fortunate to have a couple of very early photographs of three Broad Gauge locomotives outside Cheltenham shed, possibly as early as 1848. One of the engines is alleged to be ‘Polar Star’, although I have not found a good reference to the source of that attribution.

 

Early Photographs taken in Cheltenham c.1848

According to the RCTS Part Two, ‘Evening Star’ was similar to ‘Polar Star’, so the photographs shown above are a useful point of reference.

 

I also wanted a larger version of the Bird drawing than that shown in ‘The Engineer’ supplement published 16th December 1910, which included charts showing various Broad Gauge engines. This led me to another of the pitfalls that are frequently encountered with published drawings! I turned to Arman’s ‘Broad Gauge engines of the GWR, Part1’, published 2018, where on p.82, there is a reproduction of Bird’s drawing from the Locomotive Magazine 1901. It is immediately obvious (from the elliptical wheels) that this reproduction is compressed in the vertical direction. These distortions always have to be watched out for!

 

Returning to the Lane sketch, I decided to create a sketch in Fusion 360, using Lane’s written dimensions. The result, shown below, looks to be proportioned similarly to the Bird drawing.

 

My Sketch based on Lane’s Dimensions

 

Although some Lane sketches appear to be accurately proportioned, this one clearly is not. Even some of his written dimensions appear to be incorrect. For example, the overall length of the boiler between smokebox and firebox is clearly marked as 7’ 9” (31mm in 4mm scale) but there are three figures written below, apparently referring to the boiler rings, that do not add up to this total – they are “2.3”, “4.3”, “3.2”. Perhaps the central figure refers to the boiler diameter over the cladding?

 

At this point, I must state that I have not made any pilgrimages to Kew or York, to study original drawings. I note that there is a lot of detailed information about dimensions of the various ‘Stars’ in the RCTS booklet but I do not know the original sources. Therefore, please exercise the caution advised by Sekon, when reading the following paragraphs concerning my own speculation.

 

Now I return to the matter of the safety valve casings. The ‘Polar Star’ photos do not show any fitted on the boiler of ‘Polar Star’, so these photos are of no help. The only guide I have is that Lane’s ‘from life’ sketch shows tall, narrow casings, similar to those on the ‘North Star’ replica in Swindon Museum, rather than the odd-looking fat tubes in Bird’s drawing.

 

I have been looking at other Lane sketches for clues and found one of ‘Hesperus’, a ‘Sun-class’ engine, with a carefully drawn casing but, unfortunately, without any dimensions being shown. To my eyes, it looks like a better-drawn version of the casings shown on the rough sketch of ‘Evening Star’. The plinth is wider than the main column and I suggest could be the source of the “1” dimension, marked on the ‘Evening Star’ sketch. Perhaps, I am just adding more ‘errors’ by my speculations but I am influenced by the ‘jizz’ of Lane’s sketch.

 

So I have continued to create a 3D-model in Fusion 360, drawing on the information contained in the photographs and the Bird drawing, as well as the Lane sketch, to re-create the frames and the haycock top of the firebox. The RCTS Part Two states that the firebox casing on ‘Evening Star’ was 4’ 10” long, which agrees exactly with Lane’s dimension, so I am content to use this figure.

 

 

My 3D-model of ‘Evening Star’ created in Fusion 360

 

Now, though, I come up against a major discrepancy between the Lane drawing of ‘Evening Star’ and the supposedly similar ‘Polar Star’, alleged to be the engine in the Cheltenham photograph.  In Lane’s sketch, the joint between the rectangular firebox and the ‘haycock’ top is well below the level of the boiler top, whereas the photograph shows a much taller rectangular box with a more ‘squashed’ haycock top.

 

In the caption to the Cheltenham photographs on p.84 of Arman’s book ‘Broad Gauge Engines of the GWR, Part One’, he asserts that “Polar Star had its frames and boiler lengthened by 2’ 0” by 1849, so we can date the photograph as prior to that work being carried out”. I am not at all sure about that. I oriented my model in Fusion 360 as closely as I could to one of the Cheltenham photographs and the comparison shows that the boiler appears significantly longer in the photo, ahead of the driving wheels, than in my model:

 

My 3D-model of ‘Evening Star with photograph of ‘Polar Star’

 

As a further test, following a method I have used on other photographs, I used the ‘perspective’ control in 'Photoshop' to allow comparison between the diameter of the driving wheel (known to be 7’) and the length of the boiler in the photograph of ‘Polar Star’

 

‘Cheltenham Photo’ with Perspective Adjustment

 

Knowing the diameter of the driving wheel was 7 feet, this comparison indicates the boiler length was (330/230) x 7 feet, i.e. 10 feet. This supports my suggestion that, at the time of the photograph, the frames and boiler of the ‘Star’ had been lengthened by 2 feet from the original 8 foot boiler length. The design of the firebox also matches Lane’s sketch of ‘Rising Star’ which was built with the longer boiler.

 

It now looks as though I shall have to make a model of ‘Rising Star’ to take this investigation further!

 

Mike