GB465583A - Improvements in instruments of sextant-type - Google Patents

Abstract

465,583. Sextant-type instruments. LEPETIT, A. Jan. 8, 1937, No. 589. Convention date, March 16, 1936. [Class 97 (ii)] [Also in Group XIX] A casing 18, Fig. 7, has two compartments of which one, 18<1>, contains a spirit level 1, Fig. 1, its illuminating devices 2, 5, and the mechanism 9-12 for moving the rotatable mirror 7, and the other 18<2>, contains an optical system 6, 7, 8, enabling the image of a star and the image of the spirit level to be brought into coincidence. The image of the level 1 is transported through the partition 19, separating the two compartments, by the reflecting prism 13, 14. In daytime the level 1 is illuminated by the removable device 2 which has striated plates 21, directing light on to the prism 3, and at night the device 2 is replaced by the lamp 5. The battery supplying the lamp 5 through a rheostat may be housed in a third compartment adjacent the compartments 18<1>, 18<2>. A diaphragm 4 with three apertures defines the line of view, and may be moved by a handle 17 to cut off the illumination for observation at night or to permit full illumination during the day. A spring (not shown) keeps the worm 10 pressed against the sector 9 to avoid lost motion. The inclination of the mirror 7 may be determined from graduations on a drum 11 integral with the mirror 7 and on the micrometer knob 12. The latter carries a paper disc 40 on which the setting may be marked by a pencil 32, Fig. 8, after each observation. The pencil 32 is pivoted on a spring plate 34 and may be moved to make a radial mark on the paper disc by the fork 35, lever 36, and spring plunger 39. A lamp is mounted in a small housing provided with mirrors to direct light on to the drum 11 and micrometer knob 12.