Expendable oceanography probe

An expendable oceanography probe of the free-falling type comprising:

• a hollow cylindrical housing;
• a front end weight element hermetically fitted into the lower end of said cylindrical housing;
• a sensor mounted on the external surface of said front end element for detecting information relating to water to be tested, said external surface of said front end element being a flat surface:
• an oscillating circuit electrically coupled to said sensor and the oscillating frequency of which is changed according to the signal from said sensor;
• an electroacoustical disk transducer to operate in radial vibration mode and electrically coupled with said oscillating circuit for radiating a sound signal corresponding to the detected information into water around the probe;
• a transducer holder hermetically mounted on the upper end of said cylindrical housing and having an end surface facing outwardly of the probe, a center axle on the end surface and a cylindrical wall around said end surface;
• and a rear end disk plate, said transducer having a center hole and being mounted within said cylindrical wall and over said center axle with said center axle extending through said hole and said rear end disk plate attached to said axle for holding said transducer on said transducer holder, said probe having an apparent density in the range of about 1.9 grams/cm.sup.3 to 2.8 grams/cm.sup.3, the center of gravity of said probe being positioned at a point between the lower end and one third the length of the probe from the lower end and along the central longitudinal axis of said probe.