Micrometer
Date
1667
Creator
Unknown, Artist
Object type
Archive reference number
Manuscript page number
p5
Material
Dimensions
height (page): 94mm
width (page): 200mm
width (page): 200mm
Subject
Content object
Description
Figure of a micrometer, with an additional slip of paper glued on the back.
Adrian Auzout's report of some astronomical observations, using an instrument which could divide a foot into 24,000 or 30,000, in Philosophical Transactions of the Royal Society, vol. 1, no. 21 (January 1667) triggered a letter from Richard Towneley in Lancashire claiming priority for William Gascoigne (c. 1620-1644). Gascoigne had applied a micrometer in the optical path of a telescope for measuring small angles by 1639. His micrometers came into the hands of Richard Towneley (whose uncle Christopher Towneley had been Gascoigne’s patron), who claimed to have improved on the instrument, though the details of the improvement are unclear. Robert Hooke substituted the solid sights with hair sights. Towneley’s letter was printed in Philosophical Transactions, vol. 5, no. 21 (May 1667) and the figures of the instrument, drawn by Robert Hooke, in Philosophical Transactions, vol. 2, no. 29 (November 1667).
This figure is copied in RBO/3/227 and RBO/3/227a.
Adrian Auzout's report of some astronomical observations, using an instrument which could divide a foot into 24,000 or 30,000, in Philosophical Transactions of the Royal Society, vol. 1, no. 21 (January 1667) triggered a letter from Richard Towneley in Lancashire claiming priority for William Gascoigne (c. 1620-1644). Gascoigne had applied a micrometer in the optical path of a telescope for measuring small angles by 1639. His micrometers came into the hands of Richard Towneley (whose uncle Christopher Towneley had been Gascoigne’s patron), who claimed to have improved on the instrument, though the details of the improvement are unclear. Robert Hooke substituted the solid sights with hair sights. Towneley’s letter was printed in Philosophical Transactions, vol. 5, no. 21 (May 1667) and the figures of the instrument, drawn by Robert Hooke, in Philosophical Transactions, vol. 2, no. 29 (November 1667).
This figure is copied in RBO/3/227 and RBO/3/227a.
Object history
The instrument was first mentioned at a meeting on 4 April 1667, 'Dr. Croune produced a letter of Mr. Townley to him, dated 25 March, 1667, taking notice of Monsr. Auzout's pretended invention of dividing a foot into 30,000 parts, and taking thereby angles to a very great exactness; and shewing, that Mr. Gascoygne had before the late civil wars both invented and used such an instrument, which Mr. Townley had by him, and of which he would send a more perfect description, if desired. Dr. Croune was requested to desire that description, and the observations made with the instrument; and Mr. Townley's letter was ordered to be entered in the Letter-Book' (Birch 2:164). Towneley's letter appears not to have been entered.
Hooke subsequently suggested he could improve on Towneley's instrument (Birch 2:187f.,197f., 204, 208).
4 November 1667, 'Mr. Hooke's description of an instrument contrived by Mr. Townley for dividing a foot into many thousand parts, and thereby measuring the diameters of planets with great exactness, was read and ordered to be registered. It was ordered, that one of the astronomical instruments for dividing a foot into many thousand parts, as it was contrived by Mr. Hooke, should be made for Mr. Hevelius, at the charge of the society, and sent to him, as from them, by Mr. Oldenburg' (Birch 2:210-11).
Printed in Robert Hooke, 'A description of an instrument for dividing a foot into many thousand parts... as it was promised, no. 25', Phil. Trans. vol. 2, no. 29 (November 1667), pp. 541-44.
The original drawing was by Hooke: 'If the residence of the worthy promiser of this instrument, Mr. Richard Townley, had not been so remote from London, nor some other impediments intervened (after it was come to hand), First on the Publisher's, then on the Engraver's side; the following particulars concerning the same, promised some months ago, had been imparted to the publick a good while before this time: For the Draught of the Figures, representing the New Instrument itself, and the Description of the same, we are obliged to the ingenuity of Mr. Hook' (ibid., pp. 541-42).
Hooke subsequently suggested he could improve on Towneley's instrument (Birch 2:187f.,197f., 204, 208).
4 November 1667, 'Mr. Hooke's description of an instrument contrived by Mr. Townley for dividing a foot into many thousand parts, and thereby measuring the diameters of planets with great exactness, was read and ordered to be registered. It was ordered, that one of the astronomical instruments for dividing a foot into many thousand parts, as it was contrived by Mr. Hooke, should be made for Mr. Hevelius, at the charge of the society, and sent to him, as from them, by Mr. Oldenburg' (Birch 2:210-11).
Printed in Robert Hooke, 'A description of an instrument for dividing a foot into many thousand parts... as it was promised, no. 25', Phil. Trans. vol. 2, no. 29 (November 1667), pp. 541-44.
The original drawing was by Hooke: 'If the residence of the worthy promiser of this instrument, Mr. Richard Townley, had not been so remote from London, nor some other impediments intervened (after it was come to hand), First on the Publisher's, then on the Engraver's side; the following particulars concerning the same, promised some months ago, had been imparted to the publick a good while before this time: For the Draught of the Figures, representing the New Instrument itself, and the Description of the same, we are obliged to the ingenuity of Mr. Hook' (ibid., pp. 541-42).
Associated place