34 
BULLETIN 17, U. S. DEPARTMENT OF AGRICULTURE. 
The insulation of the ear hi relation to temperature is its most vul- 
nerable and its most important part, the construction of the ice 
bunker coming next in importance. In the past the insulation has 
not been sufficiently heavy to maintain the low temperatures pro- 
duced by the refrigerant, and the source of refrigeration, the bunker, 
has not been able to distribute its product evenly throughout the car. 
LEGEND ■ 
if 
n{- 
m{: 
n 
vf: 
TnEPr-lCGRAPH TOP OF LOAD, BUNKER END, A/EXT TO S/DE WALL 
-.- —~ : -~s~---: ■■-£-■- ----.-_---.£_ : ~s- s: s . ■■- ss.e, : - 's ~f c = s~~-e^ 
" " BOTTOM r> T, r, r, t, t, 77 
t» t» //VS'DE CEr/TEP OF SAMEGAPPEL, BUHKER EHD, M/DDLE 
■ An/O CEHTER 
f E^ECTP/C Tr*EPMCMETEP Crj TCP CF BAPPEL , CENTER OP CAR, M/DOLE 
YI <— 1 — •— • — " " UMDER " " » " " 
I r, r, /A/S/OE CEA/TER OF SAME BARREL 
n&v{- 
< ATMOSPHERIC TEMPERATURE 
Fig. 19.— Thermograph, and electric thermometer records (warm weather), floor insulation of car wet. 
The insulation hi the side walls and floors of the cars used by six 
different lines shows no radical differences in quantity or quality. 
though the general construction hi certain cases is preferable. The 
roofs are varied hi the essentials of construction. Theoretically it is 
the roof of the car which is most severely taxed to prevent the trans- 
mission of heat. A critical study of the types of roof construction as 
given hi the foregoing pages indicates that the most efficient cars 
studied were those with the roofs which were the best insulated and 
built. It is probable that in the future more attention will be paid to 
both roof and floor insulation and that the floor will be built with the 
insulation more effectively protected against moisture. 
