The Pressure Gauge - Schäffer & Budenberg: Precision Engineers

There was an unofficial race to produce a functioning, safe and accurate system of pressure measurement in the 1840s. The huge increase in the use of steam in all walks of life was emphasising the safety issues involved with exploding boilers, whether they were on trains or stationary engines in textile mills or steam ships. Mechanics and opticians across the developing world were in their workshops testing new ideas and trying out a variety of new systems to measure pressure accurately. Accuracy was the key, something that was not occurring with the old ‘Mercury Bob’ style of pressure measurement.

You might wonder why opticians were part of this development, but many instrument makers started their lives in optical workshops. The need for accuracy and working to fine measurements was part of their apprenticeship in the optical trade, and a fair number went on to work with scientific instruments such as Bernhard Schäffer whose company produced microscopes and slides.

Photograph of a boiler explosion on a steam train circa 1860 — An extremely good reason to have an effective pressure gauge. The front of the locomotive has been blown off, and later strapped to the rear of the footplate to be towed back to the engine sheds. The size of the rivets and the height of the chimney stack shows it is an early train.

Schinz was Swiss born, but spent much of his life working around Europe as a civil engineer, mainly building bridges. He was however, multi-talented. It appears he never actually patented his gauge design outside of Switzerland and Austria. They started being commercially produced in 1845 for use on railways in the German Federation and Prussia, the success of which was reported in the British weekly newspaper The Engineer. Bourdon’s gauge which became the most commercially successful of all four designs, was based on Schinz’s work. In Prussia and the German Federation, Bourdon gauges were always known as “Schinz style” well into the 20^th century, because of the inner tube. Sydney Smith’s gauges were taken up and promoted by George Stephenson and used heavily in mines, mills and railways. His gauge followed by improvements to the original design meant a busy factory producing for the railway companies. Smith always promoted himself as the First Patentee of the Pressure Gauge; Patent No. 11711 in 1846, which was true in Britain.

Photograph of a steam train disaster due to a boiler explosion circa 1890 — This severe explosion occurred near Buxton in Derbyshire on 11 November 1921. It was the result of the loco crew not believing the reading on the pressure gauge. The loco had recently been overhauled and a mistake made with repairs to the boiler safety-valve, so that it failed to release excess steam at the pressure intended. For some weeks, various engine drivers said the pressure gauge was faulty but no real checks were done as to ascertain the problem – as it was considered that the safety valve was set correctly. It wasn’t! The result was that the boiler exploded as the engine worked its train away from Buxton. The full accident report can be found here if it is of interest.
https://www.railwaysarchive.co.uk/docsummary.php?docID=2349
Thanks to Pete Skellon for this information and the link.
The name on the trucks behind is Verdin Cooke & Co. based in Winsford, Cheshire and they were salt carriers from the many salt mines in the area.

This grounding in optical work, along with the ability to produce accurate equipment, which even a couple of decades previously was not possible, paved the way for precision in measurement. Four men produced good equipment that was patented and useable in industry all within a four year period, 1845-1849. Plenty of other inventors were snapping at their heels, but these four were successful. They were:

Eudard Schinz (1812-1855) from Coblenz in Prussia,

Sydney Smith (1803-1882) from Nottingham in England,

Eugène Bourdon (1808-1884) from Paris in France and lastly

Bernhard Schäffer (1823-1877) from Magdeburg in Prussia.

Bernhard Schäffer’s design was quite different to the capsule tube designs of Schinz and Bourdon and had more similarities to Smith’s, both having measuring systems using deflection from a diaphragm. Schäffer’s had a plate-spring which moved up and down, and this one withstood the vibrations on locomotives extremely well, unlike the early mercury gauges. At a later date this style of gauge lent itself to a wide variety of usages, especially when chemical processing and food canning became commonplace. The plate-spring could be coated with different materials that would not be affected by the chemicals being measured or contaminate the foods being canned. While Schäffer’s gauge was officially patented on 18th January 1850, the work was completed and submitted in 1849.

Diagram of Sydney Smith pressure gauge — Sydney Smith’s diaphragm gauge, patented 1853, an improvement of the first patent of 1847.

During the period of Bourdon’s development of his gauge – which lasted some years – the man who eventually produced it commercially for him was also working on pressure gauge designs. This was Felix Richard in Lyon. I think it is fair to say that the English speaking world has little knowledge of French inventors and scientists, but they were often ahead of the British, and were more often stymied by French bureaucracy than anything else – which continued to be the case when the French were building their railways, and led to their downfall in the Franco-Prussian war. (The Prussians took their troops to the front line by train!) Lucien Vidie (1805-1866) who had developed an aneroid barometer with a dial scale took Bourdon to court in a protracted legal battle (six years) which he won, because his barometer worked on a very similar style to Bourdon’s pressure gauge. Bourdon’s tube was a variant of Vidie’s capsule internally, although it would appear that Schinz also used some of Vidie’s ideas. As Schinz never patented it across wider Europe there was no court case to answer.

One of the earliest patents for a steam gauge was put out in the US in 1835 by Enos Allen. However, this was more like a fusible plug than any sort of gauge and while Allen managed to get the US government to make it compulsory for all steam ships in particular – he was thinking of the Mississippi paddle boats when designing this item, it was soon superceded.

Bourdon took his invention to London in 1851, to the Crystal Palace for the Great Exhibition – where it was seen and admired by all for its simplicity of design and use.

Edward Ashcroft, a young Irish-American visiting the Great Exhibition bought the rights to produce the Bourdon gauge in the States and it was in production over there by 1852. He made ‘improvements’ and re-patented the gauge but his improvements were not as good as they could have been. The advantage of making an ‘improvement’ to a patent meant that all the money would go to Ashcroft rather than a royalty to Bourdon. Ashcroft went on to become an extremely successful businessman and whose company still continues to this day, although part of a much larger conglomerate, but still operating under its own name.

Bernhard Schäffer and Christian Budenberg did not have the funds to go to the Great Exhibition in London in 1851. They had started their business a year previously and like many new start-ups were suffering from lack of funds for anything except the essentials.

Line drawing of E H Ashton (USA) pressure gauge — Edward Ashcroft’s ‘improvement’ of Bourdon’s gauge, patented in the US, 1853.

Having enough money to buy the raw materials to make the gauges was causing problems, and they relied on loans from family members to keep going. In the early days they relied on income from contracts to make optical and scientific equipment for Engells & Co. in Switzerland and Georg Oberhauser in Paris. However, in later exhibitions the Schäffer gauge won many medals. Both the Bourdon and Schäffer gauges are still produced in vast quantities today which shows that simplicity of design and function stand the test of time.