The china trade and the American “granite” trade had their best days from 1870 to 1876. No doubt the general expansion of trade and the temporary absence of foreign competition were the chief factors in producing this prosperity. But a great deal was due to the increased use of steam power and the introduction of automatic machinery, and also to the institution of the Potteries Board of Conciliation and Arbitration. The clay filter press, with its steam slip-pumps—patented by Needham and Kite in 1856—had replaced the old method of evaporating the moisture out of the clay slip; and during the seventies a mechanical steam-driven “blunger” and a similar “pug-mill” did away with the old laborious “blunging” and “wedging” in the preparation of the clay body. Then that form of the thrower’s wheel, known as the plate “jigger”—which revolved the flat plate moulds—came to be driven by steam instead of by a boy at the wheel handle; and instead of the skilled hand of the flat-presser, a mechanical “form” or “jolly” was used to press the “bat” on to the mould, and give the plate the right contour and thickness.[204] Such machines for making plates had been invented as long ago as 1845, but for twenty years the objections of the workmen and practical imperfections had postponed their introduction. The “form” used to be applied by hand, and the plates consequently varied in thickness, and it required great skill on the part of the presser to make them properly. The machine, on the other hand, made every plate exactly alike, and made them ten times as quickly as the old hand process. This machine did away with the work of the old skilled “flat-pressers,” and was in general use by 1870. A similar machine, with a somewhat more complicated “jolly,” or “form,” made hollow-ware, such as basins and cups, or even bellied ware, such as ewers or chamber-pots. These came into use gradually from 1870 onwards, and replaced much of the work of hollow-ware pressers and throwers. Then in the eighties came a machine for flattening out those bats of clay which were to be pressed on to the “jigger” moulds and “jollied” into flat or hollow ware.[205] About the same time, too, the steam drive came to be used for turning the thrower’s wheel and for the turner’s lathe—fitted with various devices for controlling the speed of revolution. The manufacture of potters’ machinery is now a considerable industry, and, thanks to the energy and inventive readiness of Messrs Boulton of Burslem, this industry also is centred in the Staffordshire Potteries, and has as wide a range of markets as the Staffordshire pots themselves.