The coal used in the city and neighborhood of London is chiefly brought from the northern coal district of England by large iron propeller colliers. From them it is unloaded on to a wharf, where it is screened or sifted by being thrown on an inclined riddle, the size of the lumps having some influence on the price, which is generally from $5 to $10 per tun, according to quality. It is then put in sacks, containing one hundred weight, or sometimes two each. These are loaded on large carts drawn by enormous horses, with scales and weights to each cart, and, if desired by the purchaser, the sack is weighed by the driver. When the honesty of the coal merchant and the integrity of the driver is well established, the weighing of the sack is seldom required. And in the purchase of a cartload of sacks, some three or four of them, taken promiscuously, are tested by the scales, and if found correct, the weighing of the remainder of the load is dispensed with. This mode of buying and selling coal is the result of many years' experience in the vast city of London.