Chapter 16: The Handling Of Grain

THE ELEVATOR--THE SUCTION PNEUMATIC GRAIN-LIFTER--THE PNEUMATIC BLAST GRAIN-LIFTER--THE COMBINED SYSTEM

THE ELEVATOR

On or near the quays of our large seaports, London, Liverpool, Manchester, Bristol, Hull, Leith, Dublin, may be seen huge buildings of severe and ugly outline, utterly devoid of any attempt at decoration. Yet we should view them with respect, for they are to the inhabitants of the British Isles what the inland granaries of Egypt were to the dwellers by the Nile in the time of Joseph. Could we strip off the roofs and walls of these structures, we should see vast bins full of wheat, or spacious floors deeply strewn with the material for countless loaves. The grain warehouses of Britain--the Americans would term them “elevators”--have a total capacity of 10,000,000 quarters. Multiply those figures by eight, and you have the number of bushels, each of which will yield the flour for about forty 2-lb. loaves.

In these granaries is stored the grain which comes from abroad. With the opening up of new lands in North and South America, and the exploitation of the great wheat-growing steppes of Russia, English agriculture has declined, and we are content to import five-sixths of our breadstuffs, and an even larger proportion of grain foods for domestic animals. It arrives from the United States, India, Russia, Argentina, Canada, and Australia in vessels often built specially for grain transport; and as it cannot be immediately distributed, must be stored in bulk in properly designed buildings.

These contain either many storeys, over which the grain is spread to get rid of superfluous moisture which might cause dangerous heating; or huge bins, or “silos,” in which it can be kept from contact with the air. Experiments have proved that wheat is more successfully preserved if the air is excluded than if left in the open, provided that it is dry. The ancient Egyptians used brick granaries, filled from the top, and tapped at the bottom, in which, to judge by the account of a grievous famine given in the book of Genesis, their wheat was preserved for at least seven years. During last century the silo fell into disrepute; but now we have gone back to the Egyptian plan of closed bins, which are constructed of wood, brick, ferro-concrete, or iron, and are of square, hexagonal, or round section. They are set close together, many under one roof, to economise space; as many as 2,985,000 bushels being provided for in the largest English storehouse.

Such vast quantities of grain require well-devised machinery for their transport from ship to bin or floor, weighing, clearing, and for their transference to barges, coasting vessels, or railway trucks. The Alexander Grain Warehouse of Liverpool may be taken as a typical example of a well-equipped silo granary. It measures 240 by 172 feet, and contains 250 hexagonal bins of brickwork, each 80 feet deep and 12 feet in diameter. The grain is lifted from barges by four elevators placed at intervals along the edge of the quay. The elevator is a wooden case, 40 or 50 feet high, in which an endless band furnished with buckets travels over two rollers placed at the top and bottom. These are let down into the hold and scoop up the grain at the rate of from 75 to 150 tons per hour, according to their size. As soon as a bucket reaches the top roller it empties its charge into a spout, which delivers the grain into a bin, whence it is lifted again 32 feet by a second elevator to a bin from which it flows by gravity to a weighing hopper beneath; and as soon as two tons has collected, the contents are emptied automatically into a distributing hopper. After all this, the grain still has a long journey before it; for it is now shot out on to an endless, flat conveyer belt moving at a rate of 9 to 10 feet per second. It is carried horizontally by this for some distance along the quay, and falls on to a second belt moving at right angles to the first, which whisks it off to the receiving elevators of the storehouse. Once more it is lifted, this time 132 feet, to the top floor of the building, and dropped on to a third belt, which runs over a movable throwing-off carriage. This can be placed at any point of the belt’s travel, to transfer the grain to any of the spouts leading to the 250 bins.

Here it rests for a time. When needed for the market it flows out at the bottom of a bin on to belts leading to delivery elevators, from which it may be either passed back to a storage bin after being well aired, or shot into wagons or vessels. From first to last a single grain may have to travel three miles between the ship and the truck without being touched once by a human hand.