6 BULLETIN" 86, U. S. DEPARTMENT OF AGRICULTURE. 
None of the hoops failed during the test. A {-inch oak barrel 
should probably have not less then eight hoops of the sizes of those 
used on the barrels tested, as the swelling of the wood might break 
the hoops. 
Variation in strength of barrels of the same design is due in large 
measure to the variability of the wood composing the head and 
staves. Test specimens taken from these barrels show that some of 
the staves may have less than one-fourth the strength of others. (See 
Table 1, p. 4.) Evidently no attempt had been made to grade the 
staves on the basis of strength, the only criterion of fitness being that 
the staves should be clear and straight grained. The dry weight per 
cubic foot of clear straight-grained wood is a splendid guide as to 
probable strength, the heavier, denser wood being the stronger. The 
advisability of grading staves and heading with reference to the 
strength might well be considered. 
TESTS OF MADE-UP BARRELS. 
BARRELS. 
In order to try out the effect of some of the changes in design as 
suggested above, barrels were made up with f -inch staves, {-inch head, 
and eight hoops. The staves and hoops were from the two 8-hoop, 
f-inch barrels, the heads from {-inch barrels and previously tested 
under internal pressure. In order to make these heads fit, it was 
necessary to joint fifteen-sixteenths inch off of oue stave of each 
barrel. The bilge and quarter hoops were not changed, but were 
permitted to drive farther onto the barrels. The head hoops were 
shortened \\ inches and were driven flush with the ends of the staves. 
(In the original tests the head hoops were driven beyond the ends of 
the staves, as shown in I and II of fig. 1.) The spacing of the hoops, 
weight, capacity, etc., of these barrels are shown in III, figure 1. 
In assembling the barrels the hoop joints were placed at random. 
INTERNAL-PRESSURE TESTS. 
The two made-up barrels were tested under internal pressure. The 
results of these tests showed them to be fully equal to the barrels 
with {-inch heads and staves. One of these barrels withstood a 
pressure of 34 pounds per square inch up to the time the head began 
to fail, when the pressure was released. The increased capacity of 
the barrel under this pressure, due primarily to the springing of the 
heads, was 8J pounds of water. On release of the pressure the barrel 
resumed its original form with no apparent leakage. 
The head of the second barrel was broken out by a pressure of 38 
pounds per square inch. 
Neither of these made-up barrels showed any leakage between the 
staves during the tests. 
