REFRIGERATOB CARGOES	411
carrying space except for the hatches. These, however, are insulated,
really being wooden boxes about 10 inches deep, cork filled. They are
neat fitting when shipped, the upper ones usually being caulked with
oakum to reduce air leakage. Sometimes further precaution is taken
by spreading a 3-meh layer of sawdust over them, "blind" hatches
being shipped overall in the usual manner. Ail ventilators are fitted
with wooden insulated plugs which are clamped in position from inside
the hold.
The illustration shows the method of insulating a refrigerating
chamber showing some of the sections lifted and the brine pipes on the
bulkheads.

Fig. 5.
The Cooling is obtained by means of pipes of about 1J inches diameter
through which is circulated brine of a density of about 1047 ounces at a
delivered temperature of about 10° F. These pipes are secured to the
wooden sides, bulkheads, and deckheads of the holds, more piping
being fitted in the upper than in the lower portion of the spaces {hold or
deck). 3-inch square battens are nailed athwartships on the floors,
being spaced about 14 inches, and 2-inch square battens are nailed
vertically to the sides and bulkheads. These battens prevent the meat
from being stowed closely against the boarding and consequently
losing the air circulation. All pillars, ladders, etc., are lagged with
rope. When the hold is loaded, the temperature is ascertained by
means of thermometers which are lowered through pipes from the
weather deck.
The Preparation of the Hold for meat is important. The pipes and
sides of the ship, which are varnished, are washed down with a disin-