MILLS, KILNS, MALT-HOUSES, ETC. >65 the two pair of stones, b, and of the sack-hole, c, for allowing the corn to be raised by the tackle into the bin floor. The trapdoors of the sack-hole fold upwards, so as to give passage- way to the rising sack, and they fall close down again directly after it has passed. There is a hole between the two flaps for the chain to hang through ; and d is the step-ladder. The fran-iing is of foreign fir ; the plate is 6 inches by 7 inches; and the joists, 12 inches apart, and 6 inches by 2 inches, are mortised into girders 10 inches by 10 inches ; as also are the trimming joists which support the stones, and are 8 inches by 9 inches. Fig. 1116 is a plan of the bin floor, on which the corn to be ground is kept for supplying the stones, for which purpose the bottom of the bins slope to a centre, where there is a wooden trunk passing downwards through the floor, to convey the corn to the stones. The dotted lines represent the sides of these bins, which are generally about 3 feet 6 inches high, and are formed of inch wrought deal boarding nailed on fir bearers. The plate is 6 inches by 6 inches, the girders 8 inches by 10 inches, with the joists 5 inches by 3 inches mortised into them ; e is the sack-hole. Fig. 1117 is the upper floor to 1116 1117 1118 get at the machinery : the plate is 6 inches by 6 inches ; the girders 9 inches by 8 inches ; and the joists 4 inches by 3 inches. Fig. 1118 is a plan of the horizontal framework which carries the wind-shaft, and forms the base of the head or cap of the mill. The plates are 10 inches by 12 inches; the diagonal braces 7 inches by 6 inches ; and the centre brace 10 inches by 8 inches. On the under side of this fram- ing, and bolted to it, is a circular curb or wooden ring, /. There is a similar curb on the top of the fixed building. These curbs are to allow of moving round the head or cap ; for it is necessary, as the wind changes its direction, to turn the sails about so that the axis or wind-shaft may be always in the direction of the wind. This motion is effected by turn- ing the head of the mill roimd upon the fixed part on the curb at the top of the framing of the house of the mill, and is represented in section by I, in fig. 1119, between which and the movable curb, m, attached to the bottom of the frame of the head are fixed a number of rollers. The movable curb, m, of the cap lies upon these rollers, which are kept equi- distant from each other by the centre-pins being fitted into a circular hoop. Bv these means, though the head of the mill with the wheels and sails weighs several tons, they can be made to turn round to face the wind by a slight force ; n is the centre- brace of the head, turning on the pivot, o ; p, the top of the vertical shaft on which, a short distance down, is a wheel called a trundle or lantern, which works into the cog- wheel on the wind-shaft, and so gives the rotatory motion to the shaft ; q is one of the ribs of the head. In fig. 1118, the wind-shaft or horizontal axis, r, is made of cast iron, and is octagonal, thickest at the end next the sails, and having two cylindrical necks 3 X
