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Construction and operation of a device to measure gel rigidity is described. A commercially available force gauge capable of recording peak force measurements of up to 200±0.1 g is mounted on an easily constructed device consisting of a frame with a motor which moves a platform supporting a Petri plate up or down at a controlled speed. The force gauge probe pierces the gel in the Petri plate, at which time the peak force is recorded to give an estimate of gel hardness. Using both agar and gelrite, an example of the use of the device is given. Tests on a series of different calcium concentrations in gels of varied strengths demonstrate that the patterns of gel hardness differ. Finally, the rigidities of three typical media (half-strength Litvay, DCR, and Murashige and Skoog) on both gel types are compared.