A Warp tension recorder was deviced to investigate the acting tension between the back-rest and the lease-rod. The essential part of the recorder consists of a small crank shaft, a recording needle fixed to the shaft, and a drum driven by the bottom shaft of the loom. A stripe of warp threads, about five cm in width, pass round the small crank-pin and act. to give a clockwise rotation to the crankshaft, but the moment of force is balanced by an anti-clockwise moment of force produced by the elongation of a herical spring connected to the recording needle. This needle receives to-and-fro motions during the weaving operation and records them on the recording paper fixed round the drum. To indicate the four positions of the crank of the loons (front, bottom, back and top center) on the tension curve, it is so arranged as to give small spots on the curve by electric spark. Special arrangement is deviced to give up-and-down motion to the recorder corresponding to the movement of the back rest.
It was proved analytically and experimentally, that the error due to the inertia of the moving parts was negligible. The deformation of the spring improperly eases the strain of the threads on the tester and apt to cause some error on the result, but this is eliminated by the introduction of a reasonable graduation method.
As an example of application of the recorder, several kinds of tension cycles were taken under various weaving conditions and their characteristics were discussed.

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