Hygroscope
Date
7 October 1663
Creator
Unknown, Artist
Object type
Archive reference number
Manuscript page number
p1
Material
Dimensions
height (page): 362mm
width (page): 234mm
width (page): 234mm
Subject
Content object
Description
Drawing of a hygroscope, used to make measurement of the dryness and moisture in the air, in a paper on weather by Robert Hooke. The instrument relies on a ripe wild oat beard attached to a dial, which curls and straightens depending on the moisture in the air. Hooke indicates that the dial should be created in the manner described by Emmanuel Magnan.
The original drawing is at Cl.P/4i/25/001.
The original drawing is at Cl.P/4i/25/001.
Transcription
The Degrees of Dryness and Moysture in the Air; which may be most conveniently observed by a Hygroscope, made with the single beard of a wild oats perfectly ripe, set up right and headed with an Index, after the way describe by Emmanuel Magnan; The conversations and degrees of which may be measured by divisions made on the rim of a Circle, in the Center of which, the index is turned round; the beginning or standard of which degree of Rotation, should be that to which the index points, when the beard being thoroughly wet, or covered with water is quite unwreathed and become straight
Transcribed by the Making Visible project
Transcribed by the Making Visible project
Object history
At the meeting of the Royal Society on 7 October 1663, ‘Mr. Hooke’s paper concerning the observables for making a history of the weather was read, and ordered to be reviewed by the president and Sir Robert Moray, and then to be registered, and sent to the several persons, who had been engaged in this work of observing the changes of weather, as Dr. Power, Mr. Beal, etc.’ (Birch 1:311).
Figure printed in Thomas Sprat, The History of the Royal-Society of London for the Improving of Natural Knowledge (London: Printed by T. R. for J. Martyn ..., and J. Allestry ... 1667), p. 173.
Figure printed in Thomas Sprat, The History of the Royal-Society of London for the Improving of Natural Knowledge (London: Printed by T. R. for J. Martyn ..., and J. Allestry ... 1667), p. 173.
Related fellows
Robert Hooke (1635 - 1703, British) , Natural philosopher