Abstract: A measurement cell for an electric conductivity measuring instrument capable of measuring an electric conductivity. An electric conductivity measuring instrument includes a measurement cell, two electrodes, and a resistance calculation device. The measurement cell has a double cylindrical structure composed of a glass cylindrical cell, through an inside of which seawater as a measurement target passes, and an insulating protective cylindrical cell. The protective cylindrical cell is formed from a material having mechanical properties such that a Young's modulus is in a range of more than 0 and 1.5 GPa or less, and a Poisson's ratio is in a range of 0.49 or more and 0.5 or less, and achieving a systematic error of 0.001 g/kg or less in a salt content in the deep sea at a depth of 3000 m or more.

Abstract: Provided is a profiling float that can minutely and surely control effective buoyancy acting on the float in itself, and usage of the profiling float. The profiling float according to the present invention is equipped with a float chamber forming an airtight internal space, a fluid storage part provided in the float chamber and storing a fluid for control of buoyancy, a bladder provided at the exterior of the float chamber, in the interior of which the fluid for control of buoyancy is filled to change a volume thereof, thereby controlling buoyancy acting on the profiling float, a pump mechanism for transferring the fluid for control of buoyancy between the bladder and the fluid storage part, and a driving source for driving the pump mechanism, wherein the pump mechanism is composed of a gear pump.

Abstract: Provided is a profiling float that can minutely and surely control effective buoyancy acting on the float in itself, and usage of the profiling float. The profiling float according to the present invention is equipped with a float chamber forming an airtight internal space, a fluid storage part provided in the float chamber and storing a fluid for control of buoyancy, a bladder provided at the exterior of the float chamber, in the interior of which the fluid for control of buoyancy is filled to change a volume thereof, thereby controlling buoyancy acting on the profiling float, a pump mechanism for transferring the fluid for control of buoyancy between the bladder and the fluid storage part, and a driving source for driving the pump mechanism, wherein the pump mechanism is composed of a gear pump.