Patent GB-191504227-A (GB)
Title: Improvements in or relating to Means for Determining Distances and Direction of Movement of Objects.
Inventor: BERRY ARTHUR FRANCIS
Filed: 1915-03-17
Abstract: 4227. Berry, A. F. March 17. Range-finders.-In a long home base rangefinder of the type in which the range is indicated by pivoted needles which are automatically adjusted in accordance with the positions of the sighting-devices, each needle is moved by an electromagnetic device comprising a coil in circuit with a rheostat controlled by one of the sighting-devices and a source of current of constant voltage; means may be provided for indicating the probable range of the object at a predetermined time after the moment of observation, and the sighting-devices may be capable of adjustment to any altitude for observing aircraft, and have associated with them recording-means providing data from which the altitude and course of the aircraft may be determined. Two or more needles, each adjusted by a separate sighting- device, may be provided at each range-indicator, and one or more indicators may be provided. Each needle is carried by an armature in a coil, and the rheostats and the coils associated with them are connected with a common source of current in parallel circuits. The needles a, b, Fig. 11, may be provided with hand-operated arms 21, 22 which may be adjusted in advance of the needles an angular distance equal to the observed displacement in any desired number of seconds so as to indicate the probable range after that number of seconds. Angular scales 23, 24, additional hand-operated arms, and a reflecting-surface beneath the arms may be provided to facilitate reading. The needles and arms may be graduated to show the range directly. The sighting-devices each comprise telescope i, Fig. 6, rotatable about a pivot n carried by a plate o rotatable about a hinge-pin 5 in the line joining the sighting- devices. The rheostat h may be carried by the plate o and be regulated by a contact s on the telescope i; or it may be stationary and be regulated by a contact sliding on a curved cursor carried by the telescope. As shown in Fig. 6, the sighting-device is provided with means for recording a series of observations of the bearing and altitude of the observed aircraft and the time of each observation. An arm u is geared to turn about a vertical axis w in unison with the rotation of the telescope i about the pivot n. A clock z slidably mounted on the arm u is adjusted in accordance with the inclination of the plate o by means of a spring 14 and a cord 11 connected to a circular arm 13 carried by the plate o. The arm u may be depressed by a finger-piece v so that a marker 1 records the time of the observation in the appropriate position on a record sheet x graduated by radial and circular lines. Simultaneous records at the other sighting-devices may be obtained by providing contacts 18, 19 which, when the arm u is depressed, complete a circuit 20 through electro-magnets by which the corresponding arm at each sighting-device is also depressed. The records obtained at the sighting-devices enable the position of the aircraft at each observation and its course to be plotted on a map.