and Miscellaneous Implements at Bristol. 
123 
throw given to the eccentric on the high-speed shaft is such as to 
cause the pitch lines of the two wheels to coincide at every part of 
their revolution, and the outer wheel or roller is consequently 
advanced exactly in proportion to the difference in the number 
of teeth per revolution, and in the same direction. The great 
merit of this invention is the reduction of gearing, and conse- 
quently of expense and friction. A bracket containing adjust- 
able scrapers is secured against each roller, and a rotatory screening 
apparatus is attached when required. As a means of further 
increasing the utility of these mills, chilled rolls can be sub- 
stituted for the serrated teeth ; this is important for grinding 
coprolites. A small farmer's mill costs 45/. 
Thomas C. Fawcett, of Burmantoft Foundry, Leeds, exhibited 
a Plastic brickmaking machine, No. 5648, which deserves 
notice on account of a very ingenious mechanism for causing 
an intermittent action to the pug mill. The machine comprises 
a pug-mill and a cylindrical mould. When the latter has been 
filled with clay, and its revolution prevents more clay entering, 
pressure of the clay against the revolving cylinder would be a 
waste of power, in other words, a loss of force. The object of 
the peculiar mechanism which the drawings illustrate is to make 
the action of the pug-mill so intermittent that it only comes 
into force when the mould or die has done revolving, and 
presents itself at the mouth of the pug-mill to be filled with 
clay. This is effected by a friction clutch on the pug-mill shaft. 
Fig. 28 (p. 124) shows a cross-section of the driver-wheel in the pug-mill 
shaft, with the clutch which connects it with the shaft, by the action of 
the setting-out wedge. 
Fig. 29 shows a front section at a b, and Fig. 30 the setting-out wedge. 
The steel wedge or pin is drawn in and out by means of a cam on the wheel 
of the crank shaft, in front of the machine, that presses the brick. This 
cam, through the agency of a connecting-rod, throws the pin in, opening the 
expansion-levers, and thus starting the pug-shaft, as soon as the mould or die 
has done revolving, and presents itself to the mouth of the pug-mill to be re- 
filled with clay ; then, just as the mould is filled and about to revolve, the 
cam draws out the wedge and stops the pug mill till the mould has revolved to 
another opening, and so repeats the operation. The cylindrical mould is pulled 
round by a small crank and connecting-rod, and a four-toothed ratchet-wheel 
on the shaft of the mould ; this crank being keyed on the top crank-shaft that 
presses the brick, each time it revolves and presses a brick the mould is pulled 
roxmd one-fourth or one mould, the cylinder having four moulds. The pulley, 
or sheave, on the clutch, shown in the drawings, is continually running, being 
driven by a belt from the first driving-shaft. The clutch is keyed to the pug- 
mill pinion shaft, so that when the expansion wedge pushes in, the clutch and 
pulley become, as it were, one solid piece, until the cam on the top shaft 
draws out the wedge, then the pulley runs loose on the clutch. There is 
great simplicity and ingenuity in this arrangement, which effects a consider- 
able economy of power. This machine, catalogued at 175Z., will probably 
press and make 8000 bricks a day. 
