Diagram, inside of micrometer by [Robert Hooke?] Figure of a part of the micrometer, representing the inside of the part. Figure is drawn on a slip of paper which has been enclosed. Subject: Astronomy Similar figure published in Philosophical Transactions as 'A description of an instrument for dividing a foot into many thousand parts, and thereby measuring the diameters of planets to great exactness, &c. as it was promised, Numb. 25.' [1667]