Wheeler, Daniel, a 19th-century British engineer and inventor, was the creator of a revolutionary device for kilning and roasting malt, which he patented in 1818 as an “Improved Method of Drying and Preparing Malt.” See floor malting, kilning, and malt. In traditional kilns, the germinated grain was dried by placing it in a layer on a perforated, usually metal, floor. Then the maltster would light a wood, coal, or coke fire underneath, and the hot, often smoky, combustion gasses passing through the grain would carry the moisture away through a flue. In the process, of course, some of the malt would invariably get slightly to severely scorched, while some of it might remain fairly green. The average malt color, therefore, would always be some shade of brown, and the malt would always pick up smoky flavors from the fuel—more so from dirty-burning coal or certain types of wood, less so from clean-burning coke. In Wheeler’s invention, by contrast, the perforated-floor kiln was replaced by a revolving metal drum. Thus, the malt was never exposed directly to the kiln’s fire. Wheeler had picked up the idea for his “improved method” from watching coffee being roasted. In Wheeler’s adaptation of the coffee roaster for malt-making, malt could now remain smoke-free. It could also be dried more homogeneously. Importantly, maltsters could now for the first time adjust the temperature and length of the drying processes with ease and thereby control the color and flavor of the finished malt—from gently kilned pale malt all the way to severely roasted black malt. This new flexibility in malt drying led not only to a vast array of new malts; it also spawned a revolution in beer-making. Simply put, new malts begat new beer styles, including various types of porter, stout, and pale ale on the British Isles, and märzen, Vienna, pilsner, Oktoberfest, and helles lagers on the Continent.
It was around that time, too, that the hydrometer—especially a practical model developed in 1790 by the English chemist William Nicholson—came into wide use in the brewing industry. See hydrometer. This new gadget told brewers for the first time, in no uncertain terms, that pale malts generally produce more sugar extract per pound than do dark malts. With the hydrometer in the brewhouse and the new plethora of pale and color malts in the loft, brewers no longer needed to rely on traditional brown malt and variations in the grist-to-water ratio to make different beers. Instead, they could now make any shade and flavor of beer by simply mixing extract-rich pale malts with various amounts and types of dark malt, and do so much more economically and efficiently than ever before. Among the early adopters of the new brewing techniques made possible by the Wheeler malts were such London brewers as Whitbread and Barclay Perkins, as well as the St. James’s Gate Brewery in Dublin, makers of Guinness.