The mere enumeration of the various results of Mr. Roberts's inventive skill during the period of his settlement at Manchester as a mechanical engineer, would occupy more space than we can well spare. But we may briefly mention a few of the more important. In 1816, while carrying on business on his own account in Deansgate, he invented his improved sector for correctly sizing wheels in blank previously to their being cut, which is still extensively used. In the same year he invented his improved screw-lathe; and in the following year, at the request of the boroughreeve and constables of Manchester, he contrived an oscillating and rotating wet gas meter of a new kind, which enabled them to sell gas by measure. This was the first meter in which a water lute was applied to prevent the escape of gas by the index shaft, the want of which, as well as its great complexity, had prevented the only other gas meter then in existence from working satisfactorily. The water lute was immediately adopted by the patentee of that meter. The planing machine, though claimed, as we have seen, by many inventors, was constructed by Mr. Roberts after an original plan of his own in 1817, and became the tool most generally employed in mechanical workshops--acting by means of a chain and rack--though it has since been superseded to some extent by the planing machine of Whitworth, which works both ways upon an endless screw. Improvements followed in the slide-lathe (giving a large range of speed with increased diameters for the same size of headstocks, &c.), in the wheel-cutting engine, in the scale-beam (by which, with a load of 2 oz. on each end, the fifteen-hundredth part of a grain could be indicated), in the broaching-machine, the slotting-machine, and other engines.