ABSTRACT
In 1885 themagazine Inventions and Inventors published a chart of portraits of notable inventors. Included among them was John Joly, the young Assistant to the Professor of Civil Engineering at Trinity College Dublin. He had embarked on the design of a remarkable sequence of physical instruments. From then until the turn of the century he published prolifically on new instrumentation and registered at least 40 patents. The products of his industry and imagination included a telegraphic barometer, a photometer, the meldometer, the aphorometer, a hydrostatic balance, a sea sounder, the steam calorimeter, a solar sextant, an ampere meter, a method of colour photography, sound recording by photography, a rain gauge, an electric furnace, and many more. Even in that energetic age of Kelvin, this was an impressive display of talent and ambition. He must have seemed destined to find his fortune in the commercial world. In fact his most promising business venture, based on a practical system of colour photography, ran into legal contests and never brought a large return-or so he claimed. Instead of continuing along that Edisonian path, he veered off into geology, and became one of the founders of modern geophysics.
