739 
anagem 
and charge-to-gauge distances betwcen the unbaffled and baffled ball-crusher 
gauges in these gauge blocks, it was found that the ratio of the deformation 
of the spheres in the unbaffled gauges to the deformation in the baffled 
gauges was 0.835. No significant difference in the scatter between the two 
members of the pair of baffled or unbaffled gauges was observed, 
(b) Light diaphragm-gauge blocks. -- A gauge block was designed to 
hold two diaphragm gauges, keeping the size and mass of the entire assembly 
as small as possible. These gauges were mounted by their back plates and a 
piece of steel pipe about ) ft long was used to keep them oriented toward 
the charge. Effectively there were two diaphragm gauges side by side, facing 
the charge. The weight of the entire mount including the gauges was 70 1b 
compared with 200 lb for the composite gauge block. No difference in ab- 
solute deformation or in reproducibility of deformation was observed between 
the two types of blocks. 
(c) Small crusher=gauge mounts. —— Due to the simplicity of operation 
of the ball-crusher gauges and the knorm theory of their operation, it was 
desirable to use as many of this type of gauge on each shot as possible. 
To this end, a number of different types of small ball-crusher gauge mounts 
were designed and tested. Effects of the different types of mounting upon 
absolute level and reproducibility were notcd. 
(i) Vertical drop-line mounts, Two vertical gauges were mounted 
(distance between centers 1-7/8 in.) pointing downward on one of the 3-1/) 
in. x l-in. faces of a piece of steel 13-1/2 x 3-1/4 x 1 in. (weight 1) Ib) 
which was fastened to the drop linc supporting one of the composite gauge 
blocks, The gauges were | ft above the level of the spacer line, A similar 
mount was constructed with gauges mounted in the same position except that 
the length of the block was such that tho total weight was 1/2 lb. No 
Significant differences were found in absolute level or reproducibility of 
ball—crusher gauge reading due to the different weight of mounting. Com 
parison of the side-on orientation of unbaffled gauges in these vertical 
mounts with the face-on baffled gauges mounted in thc composite gauge blocks 
(after correcting for differences in gauge-to-charge distances) gave a ratio 
of from 0.80 to 0.82 for the unbaffled deformation to the baffled deforma— 
tion. No correction was made for the difference in gauge orientation. This 
result was consistent with that reported for baffling in Sec, 13 (et), 
(ii) Crusher-gauge mount on the momentum-gauge frame, A pair of ball- 
crusher gauges was mounted face-on towerd the charge and a second pair 
mounted side-on toward the charge (face downward) in the momentum gauge 
frame. These gauges were all effectively unbaffled but there was the possi- 
bility of reflection from the momentum gauges on the frame to the ball- 
crusher gaugese For one serics of tcsts the ratio of the side-on gauge 
deformation to the face-on gauge deformation was 1,05, while for another 
series of tests this ratio was 1.07. 
(iii) Small block face-on versus side-on mounts. Further tests of 
side-on versus face-on gauge orientations and of the weight of backing of 
ball-crusher gauges were made by constructing small blocks which clamped 
