Patent GB-190922523-A (GB)
Title: Improvements in Indicating Device for Optical Measuring Instruments.
Filed: 1909-10-04
Granted: 1910-07-07
Abstract: 22,523. Zeiss, C., [Firm of]. Oct. 8, 1908, [Convention date]. Range-finders.- Consists in an improvement in the indicating - device of optical measuring - instruments, in which the scale indication of a quantity Y dependent upon an angle X varies with the different settings of X, but at the same time a second variation of this indication, owing to the quantity Y being dependent upon a second variable Z, is provided for. The change of indication of the Y-value corresponding to an alteration of the Z-value is effected by a displacement of the index and the scale relatively to each other in the direction of the scale, which is divided in such a manner that equally long scale parts correspond to the variations undergone by the Y-indications when the Z-value varies, the apparatus, through which the variation of the Y-indication is produced when the angle X is set, being adapted to the said scale. If the quantity Y be dependent upon the product of X and a third variable W, or of X and a function dependent only on W, an apparatus may be constructed so that it can be set according to the actual value of Wand the Y-indication corresponding to that multiple of X. given by the value of W or its function. A depression telemeter fitted with 'an indicating-device according to the invention is shown in Figs. 1 and 4. The inclination X of the telescope a is set by rotating the nut b on the screw bolt c' fixed to the base-plate. The nut b carries a cam b<o>, which is marked with a scale of distances Y in kilometers and acts upon the Z-scale d marked in metres and mounted on the slide e so as to be rotatable about a vertical axis. The appropriate Z-mark is used as an index for reading the Y-scale. Figs. 6 and 7 show the application of the invention to a tachymeter or instrument for measuring distances by the length of the target. In the present case it is supposed that a staff of known length is set upright at the target. The distance Y is derived from the angle X under which the staff is seen in the instrument and from the angle Z between the horizontal plane and the direction from the tilting axis of the telescope to the centre of the staff. The angle X is set by rotating a disk g, which is mounted on the flange f<o> of the tube carrying the ocular of the telescope and carries a glass plate g<1> with a central sighting-mark g<2> and a curve g<4>, the telescope being directed so that the sighting- mark g<2> coincides with the lower end of the staff and the disk g rotated to bring the curve over the upper end of the staff. The angle Z is measured by directing the telescope to the centre of the staff and reading off the angle of inclination to the horizontal, and setting the index i, which is rotatably mounted on the disk g, to the corresponding angle on the Z-scale marked on the disk. The outer point of this index moves over the Y-scale on the margin of the flange f<o> as the angle X is set by rotating the disk g. A tachymeter in which the setting of the angle Z is automatically transmitted to the Y-indication is shown in Fig. 8. The framelike index p of the Y-scale, which is displaced to indicate the range by turning the collar n<o> of a telescope until one end of the one image produced by a Rochon-prism coincides with the other end of the other image, is displaced by a pin p‹ of the index engaging a curved slot q<o> of the standard q as the angle of inclination Z of the telescope is varied. An example of the case where there is a third variable W is shown in Figs. 13, 15, 16, and 17. The instrument shown is of the kind described in Specification 22,713/06, the calculation of a side of a triangle from one of the other two sides and from the two corresponding sides of a triangle similar to the former one being rendered unnecessary by the present improvements, which enable the distance Y, Fig. 12, of the object to be found when the base-line Z and angles V and W of the triangle are given. The sighting-telescope 10 is mounted on the top of the parts 6, 7, 8, and 9 clamped together, the part 6 pivoting in a part 4 itself pivoted by a sleeve 2 on the pivot 1 of the instrument stand. The flange of the pivot 6 carries a non-rotatable disk 12, which has a graduated circle and is guided by the part 7 so as to be capable of displacement in the line of the telescope. An annular projection 13 of the disk 12 serves as a pivot for a part 14 carrying an index 15 and guided by a slotted arm engaging a bolt 5 upon the part 4. The groove 17 of a cam - disk 16 rotatably mounted between the parts 7 and 8 is engaged. by a pin 18 of the disk 12. A ring 19 carrying the scale for distances Y is rotatably mounted on the part 8 and is provided with an indexmark 21 for the Z-graduations, which are. drawn on the uppermost part 9. The index 20 for the Y-scale is placed on the cam disk 16. The instrument is placed at the vertex of the angle, V, the telescope is sighted in the Y-direction by turning about the pivot 1, and the sleeve 2 is clamped. The telescope is then sighted in the Z-direction and the pivot 6 is clamped, the positions of the parts being shown in Figs. 15 and 16. The cam-disk 16 is then rotated until the angle W is set by the index 15, as shown in Fig. 17, on the graduated circle of the disk 12 instead of the angle V. The ring 19 is then rotated to bring the index 21 of the Z-scale opposite the known value of Z, and the index 20 then indicates distance of the target on the Y-scale. The instrument can also be used for the indirect laying of ordnance. Specifications 7972/96 and 24,790/07, [Class 106, Registering &c.], are also referred to.