154 REFRIGERATION AND REFRIGERATOR INSULATION ON BOARD SHIP. 
house, one can-always throw a large part of the machine capacity to any given box 
where special need exists. To do this with a small machine would almost certainly 
rob some other box, if indeed there happened to be another box to rob. One cannot 
emphasize too strongly, therefore, the importance of having ample capacity in small 
refrigerating machines. 
In installing cooling surface in refrigerators it is often necessary to arrange the 
layout as one can rather than as one would like to do it. 
If efficiency in the use of the cooling surface is the only consideration a lower 
temperature can be secured in the refrigerator by placing the coils directly on the 
ceiling than in any other way. An arrangement of this kind, of course, is sure to 
keep the box rather moist and, except in rare instances, is not permissible. 
In a great many cases the only thing that can be done is to place the cooling sur- 
face directly on the walls of the box. There are, with this arrangement, several dis- 
advantages. In the first place, goods stored on shelves close to the coils are apt 
to be pushed against them, and constant care is essential, and unfortunately rarely 
given, to keep the coils clean. Goods placed near the coils are also colder by far 
than goods toward the middle of the refrigerator. There is no direction given to 
the circulation of the air—that is to say, there is apt to be considerable eddying be- 
tween the rising and the falling currents of air so that the circulation is often rather 
sluggish. 
There is often considerable trouble from deposit of moisture on the walls of the 
box in this arrangement. When the box stands closed for a considerable period the 
walls and ceiling become quite cold by direct radiation to the coils. When the door 
of the refrigerator is open the cold air inthe box rushes out, and warm air, often 
heavily laden with moisture, comes in. This warm air strikes the surfaces and im- 
mediately deposits moisture, often to sogreat an extent as to cause serious drip- 
ping from the ceiling on to the stored goods. Frosting on the walls is of course 
caused in the same way, but is not so serious on account of the element of dripping 
on to goods being absent. 
This deposit of moisture on the ceiling of the refrigerator is especially apt to 
occur at a point farthest from the cooling surface on the walls. This is due, un- 
doubtedly, to the sluggish motion of the air in this part of the refrigerator, the cir- 
culation being considerably better nearer the coils. The air which has been more or 
less dried by the deposit of moisture on the cooling surface gradually dries the 
surfaces with which it comes in contact as it circulates. 
The best arrangement of cooling surface in the refrigerator is either to place it 
in a loft above the box, 7. e., above the storage compartment, or in a space alongside 
of this compartment, with ample air passages to permit the circulation of the air be- 
tween the two compartments. This arrangement is, of course, inefficient as regards 
the use of the cooling surface, but gives a very much more satisfactory refrigerator. 
Moisture is deposited on the coils, the air passes back to the refrigerator partially 
dried, and, if the box is properly proportioned, the air in passing over surfaces of 
the refrigerator, as well as over the goods, dries them and keeps them in good shape. 
