Image of a distant body; and the micrometers of Malvasia, Auzout and Picard are the natural developments of this discovery.
To obviate this difficulty Felice Fontana of Florence (Saggio del real gabinetto di fisica e di storia naturale, 1 755) first proposed the use of spider webs in micrometers,' but it was not till the attention of Troughton had been directed to the subject by Rittenhouse that the idea was carried into practice.'
P. io) claim that became universal; the methods of illumination were improved; and micrometers with screws of previously unheard of fineness and accuracy were produced.
This determines the reading of the position-circle corresponding to position-angle 90° or 270 °.2 When it is remembered that the measurements of the Struves, Dembowski, Secchi, the Bonds, Maclear and of most modern European astronomers have been made with Fraunhofer or Merz micrometers it is not too much to say that fig.
The great improvement now introduced into all the best micrometers is to provide a screw s, which, not as in the Fraunhofer micrometer, moves only one of the wires, but which moves the whole micrometer box, i.e.
How would you define micrometers? Add your definition here.