8 BULLETIN 379, U. S. DEPARTMENT OF AGRICULTURE. 
HOT BOXES. 
‘The frequent occurrence of hot boxes around the machine also was 
assigned as a cause for many of the explosions. It was asserted that 
the boxes were allowed to become hot and helped to set fire to the 
machine. 
The investigators endeavored to obtain information relative to 
the presence of hot boxes, but the difficulties encountered along this 
line were increased by the fact that the average operator was not 
willing to admit that hot boxes occurred frequently in his machine. 
_ At the time of the investigation it was difficult to determine definitely 
whether a boxing had been melted by the fire or had been heated to 
the melting point before the fire started. During the conduct of the 
field investigations personal observation of machines while running 
indicated that a large number of boxings run hot all the time. In 
some cases the “ oiler” could be seen carrying water from the engine 
and pouring it on the boxes. The results of 113 investigations based 
on statements of separator men can be summarized as follows: 
INOTNOtMOKES os) eeiiegs Vie ae 72 | One to three each day___________ 2 
Mceasionars |= 2). ae eae 33 | Qne-to two each day ees 1 
QOnepeachday2e = ise eae on 5 
Although difficulty was encountered in obtaining data which were 
considered authentic, the investigations show conclusively that the 
presence of a hot box is not essential in order that an explosion may 
take place. This does not mean that a hot box may not be a con- 
tributory cause to an explosion if the heat generated is of sufficient 
intensity and so located as to cause ignition. 
DAMAGE TO SEPARATOR. 
The damage to the separators varied from very slight damage to 
total destruction. In cases where fire-fighting equipment had been 
provided the damage was much smaller than in the machines where 
no precautions had been taken. In 146 explosions and fires the 
results can be summarized as follows: 
No. cases. Per cent. No. eases. Per cent. 
Complete loss ______-____ 40 27.4: | Slight damage _________ 20 . 13540 
A TEIAOSS 658s tn So es 49 3,0) || ANON Gala Se eee ee ees 37 25.'e 
The total damage reported for all machines was about $60,000. In 
many cases after complete loss the owner was compelled to dis- 
continue threshing for the season, and a serious situation was threat- 
ened unless some remedy was found. 
DAMAGE TO GRAIN. 
In almost all cases the flame from the explosion and fire was blown 
into the straw pile, and in many instances spread to the stacked 
grain and also to the unthreshed grain in the field. As a result sey- 
