rolling mills,[1] where formerly the fly-wheel was considered a sine qua non. There was a necessity for reversal in the case of the plate mills, but the application of chain-closure there seems to have led to its use in other cases where no such necessity existed. Coupled engines are used for non-reversing factory engines also, — locomotives and marine engines may have suggested the arrangement, while its own intrinsic value has confirmed and extended its adoption. In blowing-machines, too, no less than in steam-engines, we see the same thing; by increasing the number of cylinders, by adding separate regulating cylinders having pistons driven by cams, as well as by other arrangements, frequent endeavours have been made to substitute chain-closure for force-closure.[2] We have unquestionably in all these things a distinctly recognisable tendency shown towards certain alterations of older machine-forms into others which furnish more direct solutions of the actual problem, the production of certain determinate motions.
- ↑ See for instance the reversing rolling mill engine on Mr. Ramsbottom's system in The Engineer, July 17, 1874.
- ↑ A special, but very interesting, case of the use of a second cylinder instead of a heavy moving mass, has been treated in detail (but from a somewhat different point of view) by the Translator, under the heading "Steam Economy in Pumping Engines" in Engineering, Nov. 13 and 27, 1875. Mr. Arthur Rigg's proposed "turning gear" for single marine engines is also a case in point. Instead of using two identical chains, as in Fig. 149, he makes the second chain auxiliary only. See Trans, of Last. Naval Architects, 1870.
