THE NOMINAL HORSE POWER OF ENGLISH TRACTION ENGINES


| May/June 1955



Belgrave, Llandrindod Wells, Radnor, Great Britain

We print herewith the letter accompanying the article 'The Nominal Horse Power of English Traction Engines' by Mr. W. Michael Salmon.

First I must say how pleased I was to see my letter to you in print and especially the two photos of my engines. I had never intended or expected that you should print my letter, but nevertheless it seems to have caused some interest among your folk for I already have letters here to answer from your readers. This is most encouraging.

Now Mr. Pratt of Capel St. Mary, who is a very good friend of mine, tells me that you have asked him about our rating of engines by their NHP and he asked me to answer you on that point. You will understand that I am in no way specially qualified to do so, except that I have handled engines of a variety of different sizes, and discussed the point with men of lifelong experience. All the figures quoted are entirely estimates from my experience, and not out of books, so some people may tend to query some of them. As one of your readers has written me on the same point I have done my comments on a separate sheet so that I can send a carbon copy to him without typing it all out twice, so please find this enclosed.

May I wish you every success for the ALBUM and yourselves in the New Year. Yours truly.

The method of indicating the size of traction engines by the 'nominal horse power' is as old as the engines themselves and its origins are lost in the mists of time. It is not based on any accurate scientific method, or mathematical calculation, and serves merely to convey an approximate idea of the size and capability of the engine relative to other similar engines.