As the climate is so much warmer in summer in the United States than in England, these kilns should have not less than fourteen chambers in the one case, and sixteen in the other. The reason is this : First, in the semi-dry process, in order to be safe from crush ing down as a result of too rapid drying, the setting should be at least six chambers ahead of the burning. Between the cham bers, in which the setters are at work, and from which the drawers are taken out, there should be three vacant chambers, or it will be too hot for men to work in the summer ; and be tween the chamber from which the brick are being taken out and the chamber just finished firing, there should be not less than three chambers cooling—if four, so much the better every way. By this it will be seen that sixteen chambers are needed ; besides, it is more economical, inasmuch as the air necessary to burn the coal as it is put in through the top has farther to travel through the hot brick, and consequently its heat is inten sified in proportion, and so on the other side, in firing, every particle of heat is utilized ; so much so that it is possible to stand in the smoke-chamber, at the bottom of the shaft, with out inconvenience from either heat or smoke.
Secondly, where brick are dried before setting in the kiln, fourteen chambers will do, still leaving the same vacancies be tween setters and drawers in summer, but the same advantages accrue on the ground of economy, as in the case of semi- dry process. With these kilns you can use coal that cannot be used in any other, and, if available, gas ; or oil is as applicable as to any other kiln. As to the men, a man accustomed to good setting in the ordinary kiln soon becomes proficient with these kilns. The setting must be done well and uniformly, and the man professing to set more than ten thousand per day himself is not the man for the business in these kilns. What is needed is good workmanship, and not bustling; the two qualifications are never found combined.