This week in 1875

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The invention consists of two large vertical brushes made of horsehair.

I still find going through automatic carwashes a somewhat unnerving experience - like being swallowed by a psychedelic nylon whale. The sooner the procedure is over the better. So I’ve never really pondered at any great depth where the technology originated.

Browsing through the early Engineer archives may just have provided the answer, though.

Pictured is an invention by the Earl of Caithness for cleaning train carriages. The article of April 1975 reports on a test of the device near the running sheds of the Great Northern Railway, at King’s Cross.

The device could clean a train carriage in just over four minutes, compared with 25 minutes for one man by hand

‘The invention consists essentially of two large vertical brushes made of horsehair driven by a little steam engine.  Water is thrown upon the side of each railway carriage, 2ft in advance of the brush, from a vertical iron pipe pierced with small holes, placed at an average distance of 8in. from each other,’ the article reads.

The invention consists of two large vertical brushes made of horsehair

‘The time occupied in so doing was four minutes and a-quarter, and although this was the first experiment tried, the results were gratifying.’

Indeed, Lord Caithness himself was quoted in the article as saying: “I am told it takes a man twenty-five minutes to clean one carriage by hand.” The toils of manual labour not being something he was probably accustomed to, of course.

Still, the article wasn’t without some more in-depth post-analysis of the cleaning process.

‘During those four minutes it became evident that three conditions at least affected the results. The chief of these was the velocity with which each carriage was drawn by the locomotive, those which were passed most rapidly being less perfectly cleansed than those drawn more slowly. Another condition was the amount of pressure of the brushes against the sides of the carriage, which was completely under the control of the man who used the apparatus. A third condition was the distance between the holes in the vertical pipes.’

Certainly something to ponder next time your car is dutifully swallowed and ejected in a clean state.