. Carnegie Institution of Washington publication. 10 cm. in diameter and 3 mm. thick. A groove was cut in the circumferenceof the wheel, so that a silk thread t could be wrapped around it. The otherend of the thread was wound around a brass screw s, about 6 mm. in diameter,turning in a nut, preferably of fiber, which was fastened to the edge of thetable by a small brass clamp. In this way it was possible to control the motionof individual fringes crossing a fiducial line in the field of the telescope. Thissimple device worked surprisingly well, a smoothly running micrometer beingpresupposed. I
. Carnegie Institution of Washington publication. 10 cm. in diameter and 3 mm. thick. A groove was cut in the circumferenceof the wheel, so that a silk thread t could be wrapped around it. The otherend of the thread was wound around a brass screw s, about 6 mm. in diameter,turning in a nut, preferably of fiber, which was fastened to the edge of thetable by a small brass clamp. In this way it was possible to control the motionof individual fringes crossing a fiducial line in the field of the telescope. Thissimple device worked surprisingly well, a smoothly running micrometer beingpresupposed. In fact, it was possible to set a fringe to a few millionths of acentimeter. Later the micrometer-head was grooved and a finer turning-screw suitably attached to the base B of the apparatus. (Cf. § 70, below.) The fringes should be widened as far as convenient, by rotating the gratingon the axle e, figure 2, by aid of the set-screws d. In this case they climb upor down the transverse strip as 5 in figure 4 is slowly rotated. Fringes movinghorizo
Size: 1684px × 1484px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookidcarnegieinst, bookyear1917
