A detailed discussion concerning the 
significance of hydrographic wire angle and 
azimuth information has been provided by 
Carruthers (2. Carruthers et al., 1954). 
In a subsequent paper (3. Carruthers, 
1959) he has described an instrument for 
measuring wire angle and set. Due to various 
mechanical disadvantages of the Carruthers 
indicator its performance in the field proved 
to be somewhat unreliable. A new design 
approach was pursued, resulting in the devel- 
opment of a more efficient hydrographic wire 
slope and azimuth indicator. 
THEORY OF OPERATION 
In this new indicator, (Fig. 2) a verti- 
cally orienting and magnetic north-seeking 
unit of practically neutral buoyancy is housed 
spherically to allow the inner unit to pre- 
serve its northward and vertical orientation, 
regardless of the disposition of its housing. 
A float secured to one end of the inner mem- 
ber insures its vertical orientation, while 
magnetic needles attached to this unit cause 
it to seek magnetic north. The spherical 
shape of the inner member permits its being 
locked accurately, relative to the wire 
orientation. 
DESIGN The plastic hollow inner sphere is 
provided with a spherical glass float at its 
upper pole. Two magnetic needles are mounted 
along the horizontal axis of the inner sphere. 
Sufficient ballast to cause the inner sphere 
to approach neutral buoyancy in salt water is 
attached to its lower pole. A glass bead 
bearing is fixed to either pole of the inner 
sphere. The outer housing is composed of two 
flanged plexiglass hemispheres bolted to- 
gether through short plastic spacers placed 
between the flanges. This space is occupied 
by a pair of caliper clamps, each of which is 
pinned at one end and free to swing horizon- 
tally between the flanges. The unpinned 
clamp ends are bound together with elastic 
bands. Upon messenger impact a wedge spread- 
ing the clamp ends apart is removed, allowing 
the clamps to lock securely under elastic 
tension around the inner sphere. Both inner 
sphere and outer housing are free-flooding. 
The upper hemisphere of the outer housing 
is inecribed with latitudinal lines represent- 
ing the degrees of inclination. The inner 
sphere is marked around its equator with a 
compass rose; longitudinal lines pass through 
every 10°. Thus both wire slope and azimuth 
may be read directly. Due to the convergence 
247 
of the longitudinal lines at the poles of the 
inner sphere, precise reading of azimuth becomes 
increasingly difficult with wire slopes of Te 
or less. Because the diameter of the inner 
sphere is slightly less than that of its 
spherical housing, slight horizontal displace- 
ment is possible. However, the caliper clamps 
are designed to correctly re-center the inner 
sphere if this displacement occurs. A framework 
supports the outer housing longitudinally and 
may be clamped to the hydro wire with a slotted 
bolt-and-wing nut arrangement. This framework 
contains the caliper clamp releasing wedge and 
plunger rod, as well as the messenger release 
mechanism, which consists of a short rod butted 
against the plunger rod and mounted on a compress- 
ion spring. 
STERILE BIOLOGICAL SAMPLER 
INTRODUCTION 
Investigations by the Department of 
Microbiology concerning the distribution and 
biology of salt water yeasts and fungi have 
given rise to a need for water samples of two 
liters or more which are free from micro- 
biological contamination from sources other than 
the point at which the samples are gathered. 
Available sterile samplers (4. ZoBell, 1946 and 
5. Sirokin, 1961) have had inherent depth and 
capacity limitations. 
THEORY OF OPERATION 
DESIGN The sampler subsequently designed 
operates on the principle of a bellows. (Fig. 3). 
A pliable air evacuated and sterilized container 
is fitted with a tape-sealed check valve and 
secured to a hinged framework by means of 
pockets attached to both sides of the pliable 
container. This framework consists of two 
fork-ended plates, hinged together, under- 
spring torsion. Upon messenger impact, a plunger 
rod is depressed simultaneously disengaging two 
levers which hold the plates together, thus 
permitting the hinged plates to swing apart. 
The lower lever also serves to remove the tape 
seal from the valve. The collapsed pliable 
container is thereby pulled open into its full 
3 dimensional configuration, and, in so doing, 
water is forced into the container. After 
equilibrium is achieved, no more water may 
either enter or escape from the container. 
The messenger release mechanism is activated by 
the plunger rod upon messenger impact. A small 
quantity of sterile salt water, initially intro- 
duced into the container facilitates valve 
action. 
