"In the side wall of the byre, and opposite to the heads of the cattle, are constructed three ventilators; these are placed at the distance of about two feet four inches from the ground, in the inside of the byre, and pass out just under the roof. The inside openings of these are about thirteen inches in length, seven in breadth, and nine in depth; and they serve two good purposes. The breath of cattle being superficially lighter than atmospheric air, the consequence is, that in some byres the cattle are kept in a constant heat and sweat, because their breath and heat have no way to escape; whereas, by means of the ventilators, the air of the barn is kept in proper circulation, which conduces as much to the health of the cattle as to the preservation of the walls and timber of the byre, by drying up the moisture produced from the breath and sweat of the cattle, which is found to injure those parts of the building." MILKING. The operation of milking should, if possible, always be performed by the same person, and in the most gentle manner; the violent tugging at the teats by an inexperienced hand is apt to make the animal irritable and uneasy during the operation, and unwilling to be milked. Many of the diseases of the teats and udder can be traced to violence done to the parts under the operation of milking. Young animals are often unwilling to be milked: here a little patience and kindness will perform wonders. It is not the quantity of milk that gives value to the dairy cow; for the milk of one good cow will make more butter than that of two poor ones, each giving the same quantity of milk. Its most abundant principles are cream, caseous matter or curd, and whey. In these are also contained a saccharine matter, (sugar of milk,) muriate and phosphate of potassa, phosphate of lime, acetic acid, acetate of potassa, and a trace of acetate of iron. The three principal constituents (cream, curd, and whey) can easily be separated: thus the cream rises to the surface, and the curd and whey will separate if the milk becomes sour, or a little rennet is poured into it. When milk is intended to be made into cheese, no part of the cream should be separated. Good cheese is, consequently, rarely produced in those dairies where much butter is made; the former being robbed for the sake of the latter.