Abstract: A folding square framework which may serve as a support for a tensile canvas or membrane. This framework, which may be mounted on a fixed column or wall, may fold, around hinges set at 54.3° to the longitudinal axes of each member of the framework, at each corner, compactly together such that all four sides of the framework are rested parallel with one another, perpendicular to the plane of the unfolded structure.

Abstract: An electromagnetic shearflowmeter for remote oceanic applications is disclosed, wherein a pair of housings, each having disposed therein an electric coil, are spaced to define an open cylinder through which a fluid in which the shearflowmeter is immersed may flow relatively free of obstructions. Electrodes are embedded symmetrically in the surfaces of the housings for sensing electromagnetic signals deriving from activation of the coils and which signals are modified as a function of the rate and direction of flow through the open cylinder of the fluid in which the apparatus is immersed. A plurality of such apparatus may be operated at different depths along a common mooring to measure differentials of flow, also called shear, within the fluid system. An electronic amplification circuit having an excellent common mode-rejection ratio and common mode range, used in conjunction with the other apparatus, is also disclosed.