REFRIGERATION AND REFRIGERATOR INSULATION ON BOARD SHIP. 159 
deck plates, it is very difficult to do the work with sheet cork. It would be difficult to find a 
rougher place, or a place where it would be more impossible to fit sheet cork, than in such 
places; it is, commercially, impossible to make tight joints with the sheet cork between 
the frames and about all the rivets and landings of plates, and particularly about fore-and- 
aft stringers. This is a class of construction to which sheet cork does not lend itself as 
an insulator. I have had considerable experience in connection with this problem of refrig- 
eration and insulation in vessels, and have found that a material which can be packed in 
behind boarding gives probabilities of the best results, such as granulated cork, mineral 
wool, cowhair, etc. Tests show that 4 inches of sheet cork and 7 inches of granulated 
cork have about the same heat-resisting effect, and assuming 8 inches for the granulated 
cork (penalizing the granulated cork), we would have a cubic foot of granulated cork equal 
in heat-insulating effect to half a cubic foot of sheet cork. The sheet cork costs some 54 
cents against the granulated cork’s 16 cents. This seems to indicate that in large installa- 
tions, at any rate, the sheet cork is prohibitive. That has been my experience. 
On page 154 the author suggests there is a possibility of provisions or other goods being 
stored directly against pipes. It is customary to put wooden battens over the face of and 
clear of the pipes, to keep the meat and provisions from touching the pipes. On large’ ves- 
sels only the overhead pipes are left exposed. All side piping has to be protected, and the 
bulkheads, where there are no pipes, have battens, to allow ventilation behind them. We 
have no difficulty in maintaining even temperature throughout ships carrying frozen meat— 
there is a difference of less than one degree in the various parts of the ship which are re- 
frigerated. In chilled-meat cargoes, we maintain temperatures to within half a degree, and 
only have coils on the sides and overhead. 
As to the question of leaking of air into the room, when the door is open, the air strik- 
ing on the walls and ceilings, that will occur if air locks are not provided; and where the 
rooms are of sufficiently large capacity to enable the use of air locks or a small entrance 
chamber it should be done, obviously. 
On page 156, first paragraph, the author states:—‘In cases where the escape of gases 
would not be serious and where, on the other hand, cost of operation would be an impor- 
tant item, and where large quantities of refrigeration were required—especially in cases 
where a separate engine-room could be provided for the machine—the ammonia and car- 
bonic acid type of machine has been the ruling type. In merchant service there are a 
number of these machines placed directly in the engine-room. It is unnecessary to dwell on 
the importance of locating the machine in this way to the engineer who has been through 
the experience of an accident or the unexpected escape of gases.” 
It does not seem reasonable to class carbonic acid and ammonia together in this con- 
nection. One is a poisonous gas and the other is not. Unless the carbonic acid escapes in 
such enormous quantities with very poor ventilation so that it cannot get away, it will do 
no harm. Carbonic acid is safe to all intents and practical purposes for use with machines 
placed in the main engine-room. 
I would not recommend an ammonia machine, except in the smallest sizes, to be placed 
on the lower platform. The machines of even the small sizes are usually placed on the top 
sides. The smallest ammonia machines (1 ton capacity) so placed rarely contain more than 
30 pounds of gas, and leakages that occur are not serious at all. 
On page 156, end of third paragraph, the author refers to the wear on piston rods and 
