Credit: ©The Royal Society
    Image number: RS.14233

    Diagram explaining the raising of a weight by inflating a bladder

    Date
    4 March 1663
    Creator
    Unknown, Artist
    Object type
    Archive reference number
    Manuscript page number
    p172
    Material
    Dimensions
    height (page): 350mm
    width (page): 230mm
    Subject
    Physics
       > Mechanics
    Content object
    Description
    This diagram is one of a series of figures (RBO/2i/168, 169, 172, 174 and 175) in John Wallis's explanation of the raising of a weight by inflating a bladder. In this diagram, B is a large bladder, whose neck at N is fastened to a board or post. The bladder can be inflated through a quill at Q, and P is a weight attached to the other end. Wallis observed that a weight of over 70 pounds could be lifted in this fashion.

    Wallis read his paper at the meeting of the Royal Society on 4 March 1663.

    For an earlier discussion of this experiment by William Croone, see RBO/1/108.
    Transcription
    Having praemissed these Principles in staticks; I shall now propose the Phaenomenon or experiment whereof I am to give an Account. Suppose B to be a large bladder whose neck at N, is made fast to a Board or Post, so fixed as not to stir, yet so as that through a Quill Q, the bladder may be glown up; and at the bottom the weight P, fastened to it. It is found by experience, that by a Man's breath blowing the Bladder at Q, the sides being Distended and consequently the Length contracted, a weight of 50, 60, 70 pounds or more (according to the strength of his Lungs who blows it) will be lifted up a considerable height.
    Transcribed by the Making Visible project
    Object history
    At the meeting of the Royal Society on 4 March 1663, ‘Dr. Wallis brought in his account of the experiment, wherein a weight is raised by the blowing of a bladder; demonstrating it by the principles of statics applied to the particular case; and it was ordered to be registered’ (Birch 1:206).

    At the meeting of the Royal Society on 6 November 1661, ‘Mr. Croune read his Experimental account of the raising up of a weight hung at the bottom of an empty bladder; which was ordered to be registered’ (Birch 1:53).
    Related fellows
    John Wallis (1650, British) , Mathematician
    Associated place
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          > United Kingdom
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