=Cylinder Arrangements.=--If the plant be sufficiently large so that the machine equipment can be afforded in two units then it would be proper to install freezers. Supposing then that the plant justifies this arrangement the compressors would be connected to the brine tank for chilling purposes, and to the closed cooler for circulating purposes. The gland end of the compressors would be arranged so that they could be operated independently upon the freezer space at will. =Why Brine Circulation.=--The chief reason for using brine in the moderate sized plant is that with a reasonably large brine capacity there is a reserve cold (so to speak) stored in the brine which will permit of stopping the compressor, the brine continuing in circulation by pumping, and there is less likelihood of changes in temperature. Direct expansion chilling requires an almost constant machine operation. =Air Circulating.=--The chilling of packing houses and methods involved are various, each with its advocates. In Europe and where English methods are followed the system is chiefly forced draft. This system has been used to some extent in the United States, but the majority of the coolers are handled with lofts, and circulation therefrom is of natural sequence. The cellars and freezers are handled by pipes hung in the rooms. =Force Draft.=--The force draft or indirect cooling system consists of forcing chilled air, cooled by passing through batteries of expansion coils operated dry, or over which brine is passed, through a series of ducts, and withdrawing it; thence passing it through the coils and repeating. It is not favored among American packers owing to a belief that it increases shrinkage, and tends to darken beef; that large quantities of cold air are lost through open doors; because of the expense of operating fans, as well as the room taken up by ducts and the interference occasioned with meat rails. =Coil Room Systems.=--The overhead bunker system as described under “_Construction_” in this work details the application of the United States practice. Accepting the use of the coil room system and of still storage the question arises as to the application. A visit of inspection to the various packing plants throughout America will impress one with the fact of the existence of a wide variation of opinion and practice with regard to the methods of applying refrigeration for packing house purposes. There are two principal applications--direct expansion, wherein the ammonia gas is circulated through the coils throughout the premises, and brine circulation, open or closed, where chilled brine is circulated throughout the works. =Brine Chilling.=--The two types of brine chilling, open and closed, produce the same result, except as to the actual brine cooler, of which there are several, namely: (1) Brine tank in which are submerged ammonia expansion coils.