Improvements in or relating to Goniometers, Geodesic and similar Instruments.

摘要

9974. Schneider, E. May 7. Goniometers; theodolites.-Relates to a graduated scale and index for anglemeasuring instruments, such as goniometers, theodolites, &c., the object being to reduce the possibility of errors due to rotation of the oparating-device in the wrong direction. Agoniometer mis operated through worm gear o, h by means of a crank e, on the shaft of which is mounted a disk g carrying diametrically-opposite index marks c, d. A fixed semicircular scale a has a zero mark band graduations numbered in the same circular direction, the graduations being all contained in the semicircle. A screen i fixed to the scale a covers the lower half of the diak g, so that one only of the marks c, d is visible at a time. Thus the visible index mark always moves in the direction in which it is desired t) displace the instrument.