Firth Hardometer by Thos Firth & John Brown Ltd of Sheffield. Although classed by the makers as a catalogue, the publication givesfull details of the machine's design, its dimensions, principles of operation,
 construction, the various models,  calibration, hardness conversion charts, Theoretical Notes on Brinell and Diamond tests, determining hardness of surface layers and thin sections, changing the ball or diamond, preparation of samples, making and reading the impression, table showing the correct objective to use and much advice about getting the best from the machine, etc.