Credit: ©The Royal Society
    Image number: RS.16633

    Powder mill for gunpowder

    Date
    22 July 1663
    Creator
    Unknown, Artist
    Object type
    Archive reference number
    Manuscript page number
    p125
    Material
    Dimensions
    height (page): 353mm
    width (page): 233mm
    Subject
    Content object
    Description
    Figure of a trough of a powder mill used to make a new kind of gunpowder (designed by Prince Rupert), which was more powerful than the best English powder. The trough, which is an oval shape, should be about 19 inches deep and at its widest breadth, 14 inches to the centre. The manner of making the gunpowder (mixing 2 ounces of brimstone and 2.5 ounces of coal to every pound of saltpetre) was reported and ordered to be registered at the meeting of 22 July 1663.

    This manuscript is a copy of Register Book no. 2 (RBO/2i) and some letters to the Royal Society, all from between 1662 and 1664.

    This image can be found in the Register Book at RBO/2i/286. Another copy can be found at MS/776/468.
    Transcription
    For this purpose, you must have ready a very just ballance with two pretty big copper seales, and a pile of Silver weights and then see how big your stamping Mortar is, if you mean to worke your powder with your hands, or the wooden-trough, of a Powder-Mill, wherein it is to be pounded for accordingly you are to order your Dose, that so you may not doe too much or too little, and that the Powder may be wrought enough. E.h. If the trough of the Powder-mill have about 19 inches in depth, and 14 inches in the midst, where tis largest for to be of a right shape and proportion as it ought, it must be ovall, after the manner in the figure, the Powder falling from the top, whether it wont up by all the sides, handsomely down again, into the midst under the Pestles.
    Transcribed by the Making Visible project
    Object history
    At the meeting of the Royal Society on 22 July 1663, ‘[Sir Robert Moray] related, that prince Rupert had made a new kind of gunpowder, in strength so far exceeding the best English powder, that trial being made with a powder-trier, it was found to be in the proportion of 21 to 2. It was desired, that a trial of it might be made before the society’ (Birch 1:281). The text and figure are printed in Birch 1:281-85.
    Related fellows
    Prince Rupert (1619 - 1682, German)
    Associated place
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