ABSTRACT
R. L. Edgeworth and his friends, however, did actually perform experiments in telegraphy over short distances as early as 1767. The earliest mechanical calculators, were invented in the seventeenth century. They were of two principal kinds, comprising, on the one hand, logarithmic slide rules, and, on the other, calculating machines designed to perform certain operations in arithmetic by the agency of interlocking wheels. The chapter deals with a miscellaneous group consisting of the following: an improved oil-lamp, coal-gas illumination, improved coin-minting, the copying press, the weigh-bridge, and the windmill ventilator. During the closing years of the eighteenth century, William Murdock, whose other work has already been described, experimented with coal-gas for purposes of illumination. His apparatus consisted of an iron retort with tinned copper and iron tubes through which the gas was conducted to a considerable distance, and was kindled there, as well as at intermediate points, through apertures of various shapes and sizes.
