Featured in the Great Exhibition of 1851, Dr. Merryweather of Whitby's Tempest Prognosticator was designed to warn of approaching storms. Described as an ingenious device for the protection of life and property, it houses 12 leeches, disposed each in a transparent glass bottle, arranged in a circle "in order that the leeches might see one another and not endure the afflictions of solitary confinement". Atmospheric pressure agitates the leeches, who rise and move whale bone buttons, sounding the bell and so warning of approaching tempests. See 10423321 for a reconstruction.