Diagram, micrometer by [Robert Hooke?] Figure of a micrometer on the first page. Labelled fig. 4. This is a closeup of a piece of the micrometer, with a handle and measuring guide to pull the piece accordingly. Parts are lettered. Subject: Astronomy 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]