A handy little grinding machine by the same well-known firm is shown in Fig. 41; a liquid-paint mixer, in Fig. 42; and a single pug mill for paint or putty, in Fig. 43. Neither of these machines requires any special description, as the mode of application is evident from the illustrations. [Illustration: Fig. 41.--WRIGHT’S SMALL PAINT MILL.] This firm are also the manufacturers of Clark’s patent paint mill, illustrated in Fig. 44. This mill differs from the ordinary mills in having five instead of three rollers. The material is fed in between the two uppermost rollers, being prevented from spreading too much by means of wooden cheeks shaped so as to fit between the rollers and form a kind of hopper in which the material to be ground is placed. From these two rollers it passes to a third and [Illustration: Fig. 42.--LIQUID-PAINT MIXER.] fourth placed below, and receives a final grind from the fifth roller in front of the machine, from which it is delivered to the spout as shown. The rollers are all of granite turned truly cylindrical. They are 15 inches in diameter and are mounted on strong steel spindles. These spindles run on bearings working in guides, by means of which the distance [Illustration: Fig. 43.--SINGLE PUG MILL.] apart of the rollers and the fineness of the grinding can be adjusted. It will be seen that the driving-shaft of the machine is the lowest of the six shown. It drives by means of spur gearing roller number three, and through it the other rollers of the mill. No two rollers working together revolve at the same speed, and hence one rubs over the other, and they thoroughly grind the material between them. In the common three-roller mills it is necessary to pass the material to be ground through the mill twice, but in this machine one passage is sufficient, so that both time and floor space are saved, as the machine, it is claimed, does the work of two ordinary mills. Another noteworthy feature of this mill is that on No. 2 roller is a [Illustration: Fig. 44.--CLARK’S PATENT GRANITE-ROLLER MILL.] lateral motion giving a sidewise movement of ¾ inch. This is also applied to No. 4 roller, and gives the same movement. Each roller can be separately and easily adjusted by means of adjusting screws. The fifth roller is the delivery roller. The weight of No. 2 roller is carried by a strong spring fixed between the bearings of rollers Nos. 2 and 3, so that by the movement of the adjusting screw, the No. 2 roller can be brought down upon No. 3 with the required pressure.