4 BULLETIX 1290, U. S. DEPARTMENT OF AGRICULTURE 
dampers and plugs, the manipulation of which controls the flow of 
air into the different holds. Two air passages extending athwart - 
ships connect the port and starboard air chambers. One of these 
serves as a common discharge chamber and the other as a common 
suction chamber for both fans, which are located in the suction 
chamber. 
On referring to Figure 1 the method of operation for securing the 
circulation of air is obvious. To cause the air to circulate across the 
hold from port to starboard, the dampers B in the suction chamber 
and C in the discharge chamber are closed, and dampers D in the 
suction chamber and A in the discharge chamber are opened. This 
arrangement allows the fans to draw the air through the dampers 
D from the port ducts, which empty into the port air chamber, and 
discharge it under pressure into the discharge chamber, thence 
through the damper A into the starboard air chamber and into the 
ducts leading into the holds. On reaching these ducts in the holds 
formed by the apron and the ship's side the air is forced along the 
cold brine pipes and out into the hold through the small holes which 
pierce the apron. It then circulates across the hold and is drawn 
into the port-side ducts through the holes in the apron along the brine 
pipes into the port air chamber, thus completing the circuit. To re- 
verse the direction of the air movement through the hold it is only 
necessary to regulate the appropriate dampers. As far as the writers 
have been able to learn, this is the first time that this type of instal- 
lation has been used in the American fruit trade. 
During the investigation, which continued from September to 
December, 1922, four consecutive test trips were made on this vessel, 
the first leaving Xew York in the middle of September and returning 
October 2, this being the first voyage the vessel made after the in- 
stallation of its refrigerated fruit-carrying equipment. 
As one purpose of this test was to determine the efficiency of this 
type of refrigeration equipment in carrying fruit, it was necessary 
to measure the fruit temperatures in different parts of the load, to 
take air temperatures at various points where the air entered and 
left the hold, and to determine the brine temperatures in the banks 
of brine coils back of the aprons, over which the air circulated before 
and after leaving the hold containing the fruit. The brine tem- 
peratures were taken in the usual way with mercurial thermometers 
placed in the incoming and outgoing brine pipes. The temperature 
of the air as it entered the fan chamber from the holds and as it 
went into the holds was taken with thermometers. The temperatures 
of both fruit and air within the holds were measured with electrical- 
resistance thermometers attached to cables, so arranged that readings 
of the temperature within the hold could be made without entering, 
it. With these resistance thermometers it was possible to get both 
air and fruit temperatures in various parts of the hold. 
CITRUS-FRUIT GROWING IN PORTO RICO 
Citrus fruit in Porto Rico is grown on both sides of the island, 
and in some cases well into the interior. Around San Juan there are 
many orange and grapefruit groves which are well cultivated and 
cared for and have the advantage of modern packing-house facili- 
