1086 
III. INSTRUMENTATION anD RIGl/* 
The rig used for the tests is shown in Fige 1. The charge and 
gauges were on a straight line 40 feet below and parallel to the surface 
of the water. This line was attached at the forward end to a tow line 
leading up to the vessel "Reliance", and a sea anchor at the aft end of 
the line served to maintain tension as the gear was towed through the 
water. The charge was at the center of this line, and the piezoelectric 
and mechanical gauges were located forward and aft of the charge re- 
spectively. All parts of the gear were suspended from surface buoys, 
and charge-to-gauge distances were determined by steel spacer oables. 
The mechanical gauge instrumentation consisted of: 
(1) Two hegyy gauge blocks (Fig. ,1B) each containing two UERL 5 
diaphragm Baageee two Modugno gauge 3/ and two NOL ball crusher oe | 
All gauges are held face on to the charge by means of the strain of the 
spacer lines on a rigid tail extending 4 feet out from the back of the 
block. The ball crusher and Modugno gauges in these blocks were baffled 
by the face of the blook (cae 3-5 inches from center of the gauge to the 
nearest edge). The diaphragm gauges were unbaffled except by the faces 
of the gauges themselves. Lot V-B thin plates were used in the diaphragn 
gauges farthest from the charge, and lot V medium plates in those close 
to the oharge.e 
(2) Five light ball crusher gauge blocks (Fig- 1A) each holding four 
NOL ball crusher gauges. These gauges were side-on to the charge, and 
were unbaffled except for the face of the gauge itself. 
(3) One momentum gauge rig (Fig. 1C), holding two Hartmann type "i" 
and three Hartmann type "A" momentum gauges. 
Piezoelectric gauges with 2 inch and inch diameters were used; the 
smaller were 4 or 8 pile and the larger were 2 or 4 pile gauges. They 
were mounted on a_30 foot copper tube which served as a shield for the 
central sonductor4/ and a cable attached to the end of the copper tube 
was run back to a compensating network located on a float barrel about 
150 feet from the chargee From the float barrel the cable was led along 
the surface to the "Reliance", where it was terminated in a compensating 
network within the master control panel, then to the vertical amplifiers 
of modified Duliont 208 cathode-ray oscilloscopes. The main gauge cable 
used was Army-Navy type RG-41/U. 
Previous tests had shown that in order to eliminate a jagged rise 
line which had been noted on gauges at large distances from the charge, 
it was necessary to: (1) run the cable from the two pairs of gauges 
nearest the charge to the surface separately from the cables for the 
other two pairs of gauges, and (2) position the pair of gauges farthest 
from the charge at least 25 feet from the cable. The three pairs of 
gauges nearest the charge were held about 6 inches from the cable by 
H-frames having a 1 foot crosstree (Fig. 1E), whereas the pair of gauges 
farthest from the charge were mounted on a larger frame which held them 
23 feet from the cable by means of a 5 foot crosstree. 
*The list of references has been deleted. 
sore 
