730 
Report on Implements at Preston. 
stack, 23 feet square by 15 feet high to the eaves when settled, 
would require 6 pairs of screws and cross-heads, wire rope, reel, 
12 spanners, and 2 hand- wheels, at a cost of 18Z. This small 
outlay includes all that is required, except the logs of wood to 
which the screw-rods are fastened, and a few rough pieces of 
wood laid across them to give better hold of the mass. The logs 
should be G or 7 inches in diameter, and long enough to reach 
nearly to the centre of the stack ; they should be placed 4 feet 
apart. It is obvious that the long screws exposed to the weather 
must be kept well oiled, or they will soon be injured. 
