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elevation but also the true length of time fuse has to be found. This the range-finder cannot do. Hence it is that the range-finder for field artillery, although a valuable auxiliary, is not of the same importance as in purely defensive positions, such as batteries for See also:

HARBOUR (from M.E. hereberge, here, an army; cf. Ger. Heer and -beorg, protection or shelter. Other early forms in English were herberwe and haiborow, as seen in various place names, such as Market Harborough.. The French auberge, an inn, derived through

harbour See also:

defence, and See also:

LAND

land forts. RANGE-FINDER and passing through the object-glasses, each is received by an arrangement of prisms about the centre of the See also:

TUBE (Lat. tuba)

tube, and reflected through the right See also:

eye-piece. Two partial images are thus seen. The images could be See also:

UNITED

united by the rotation of one of the reflectors, but owing to the small See also:

BASE

base used the necessary See also:

MOVEMENT

movement would be so extremely small that it would be practically impossible to measure it. The difficulty has been surmounted by utilizing fixed reflectors and effecting coincidence by means of a prism of small See also:

ANGLE (from the Lat. angulus, a corner, a diminutive, of which the primitive form, angus, does not occur in Latin; cognate are the Lat. angere, to compress into a bend or to strangle, and the Gr. ayKOS, a bend; both connected with the Aryan root ank-, to

angle. The deflecting prism is situated in the See also:

LINE

line of the See also:

beam of See also:

LIGHT

light from the reflector at the right-See also:

hand end of the tube. Its multiplying See also:

ACTION

action is of See also:

GREAT

great delicacy.

The angle available for subdivision, to measure ranges between infinity and 250 yds., is only one-third of a degree. In a travel of 6 in. the prism renders accurate measurements possible within the required limits. To bring images of distant objectives into coincidence, the prism must be moved towards the eye-piece, and for near objectives in the opposite direction. The range See also:

scale is attached to the prism. A consequent See also:

ADVANTAGE

advantage is that the accuracy of the See also:

INSTRUMENT (Lat. instrumentum, from insincere, to build up, furnish, arrange, prepare)

instrument is not affected by back lash arising from See also:

WEAR

wear, or irregularity in the actuating mechanism. When once installed, the instrument is always ready for use. Should See also:

ADJUSTMENT (from late Lat. ad juxtare, derived from juxta, near, but early confounded with a supposed derivation from justus, right)

adjustment be required it is readily and easily applied. It is not within the See also:

SPHERE (Gr. vclsa?pa, a ball or globe)

sphere of this See also:

ARTICLE (from Lat. articulus, a joint)

article to enter into the detail of the adjusting mechanism. For further particulars the reader is referred to the Proceedings of the Institution of See also:

MECHANICAL

Mechanical See also:

ENGINEERS, MILITARY

Engineers, 30th See also:

JANUARY

January 1896. The working of the range-finder is so See also:

SIMPLE

simple that its use is quickly learnt by any See also:

man who can read, and with little instruction and practice he can " take a range " in 8 to 12 seconds. Besides its principal purpose, in connexion with gunnery, there are See also:

minor uses in See also:

NAVIGATION (from Lat. navis, ship, and agere, to move)

navigation and nautical See also:

SURVEYING

surveying to which the range-finder can' be applied. With the high speeds of See also:

MODERN

modern See also:

war-vessels, guns and their See also:

OBJECTIVE, or OBJECT GLASS

objective approach each other so quickly that unless ranges can be communicated from the instrument to the guns with rapidity and accuracy the range-finder is deprived of much of its value.

In connexion with the See also:

NAVAL

naval range-finder an apparatus is provided, which though not See also:

PART

part of the range-finder is sufficiently important to claim passing See also:

NOTICE

notice. The apparatus consists of a transmitting and a receiving instrument of clockwork mechanism electrically controlled. In See also:

APPEARANCE (from Lat. apparere, to appear)

appearance they resemble the See also:

ORDINARY (med. Lat. ordinarius, Fr. ordinaire)

ordinary See also:

engine-See also:

ROOM

room See also:

TELEGRAPH (Gr. Tike, far, and rypaq5eiv, to write)

telegraph, on the dials of which ranges take the See also:

PLACE (through Fr. from Lat. platea, street; Gr. IrAar6s, wide)

place of orders. The transmitter can communicate with a number of receiving See also:

INSTRUMENTS

instruments, disposed as required in different parts of the See also:

SHIP

ship. 2. Before the introduction of the Marindin range-finder described below, the See also:

BRITISH

British See also:

army in the field used the " mekometer." The instruments used by the See also:

CAVALRY (Fr. cavalerie, Ger. Kavallerie or Reiterei, derived ultimately from late Lat. caballus, horse)

cavalry and See also:

INFANTRY

infantry are smaller and lighter than those of the artillery See also:

PATTERN

pattern, but the principle involved is identical. The mekometer is practically a See also:

box See also:

SEXTANT

sextant. Two instruments are used simultaneously at the ends of a base of fixed length. One sextant, called the right-angle instrument, is fitted with See also:

INDEX

index and See also:

HORIZON (Gr. 6pfTwv, dividing)

horizon glasses permanently inclined at 45°. It consequently See also:

MEASURES

measures a right angle. In the other sextant, called the See also:

READING

reading instrument, a graduated See also:

DRUM (early forms drome or dromme, a word common to many Teut. languages, cf. Dan. tromme, Ger. Trommel: the word is ultimately the same as " trumpet," and is probably onomatopoeic in origin; it appears late in Eng. about the middle of the 16th century)

drum takes the place of the usual index See also:

ARM (a common Teutonic word; the Indo-European root is ar, to join or fit; cf. the Lat. armus, shoulder, and the plural word arma, weapons, Gr. apphs, joint, and the reduplicated apapilKSV, to join)

arm and scale. The drum is graduated spirally with a scale of ranges.

Both reading and right-angle instruments are fitted with a See also:

vane of See also:

gun See also:

metal with a See also:

white See also:

STRIP

strip down the centre to facilitate observations. Telescopes of See also:

low See also:

POWER [WILLIAM GRATTAN] TYRONE (1797-1841)

power can be fitted to the instruments, and two cords of 50 (or 251) yds. are provided with which to measure the base. Two observers attach the ends of the See also:

CORD (derived through the Fr. corde, from the Lat. chorda, Gr. xop(5rt, the string of a musical instrument)

cord of fixed length (usually 50 yds.) to their instruments and See also:

SEPARATE

separate until it is taut. The Meko- observer with the right-angle instrument moves into such See also:

METER, ELECTRIC

meter. a position that coincidence of See also:

IMAGE (Lat. imago, perhaps from the same root as imitari, copy, imitate)

image will be given between the objective and the vane of the instrument at the other end of the base, i.e. he makes See also:

ABC a right angle (fig. 3). When the right angle is established, the observer at C turns the graduated drum of the reading instrument until the image of the vane of the right angle instrument coincides with the direction of the objective. The range AC is then read on the drum. The ranges on the drum are measures of the angle BAC when the base BC is 5o yds. The mekometer is open to the objection which is See also:

COMMON

common to all range-finders requiring more than one observer. There is always a danger that observers may cause coincidence on different objectives Rightangle \ Reeding instrument h.Wetrument B •- Base ---•---- C FIG. 3. The Marindin range-finder was from 1908 gradually introduced in the infantry to replace the mekometer.

It was the invention of See also:

CAPTAIN (derived from Lat. ca put, head, through the Low Lat. capitanus)

Captain A. H. Marindin, of the See also:

Black See also:

WATCH (in O. Eng. wcecce, a keeping guard or watching, from wacian, to guard, watch, wacan, to wake)

Watch (Royal Highlanders). The principle of the instrument is that of coincidence, as in the See also:

Gautier See also:

CHRISTIE, RICHARD COPLEY (183o–Igor)

Christie, Le Cyre, Souchier, and See also:

BARR

Barr and See also:

STROUD

Stroud. But it differs from the last mentioned in that the right prism is made movable, and this movement (necessarily extremely small) is a See also:

FUNCTION

function of the recorded range. The See also:

STEEL, FLORA ANNIE (1847– )

steel tube, forming the base of the instrument, which carries the prisms,is supported inside an See also:

ALUMINIUM (symbol Al; atomic weight 27.0)

aluminium See also:

OUTER

outer tube in such a way that no See also:

DIRECT

direct See also:

SHOCK, or COLLAPSE

shock is communicated to it. The RMarindia ange- appearance of the outside of the instrument, together Finder-with the names of the various parts, is shown in fig. 4. The instrument can be used in two See also:

main positions, viz. horizontally, Instrument ready for use. FIG. 4.-Marindin Range-Finder. for ranging on upright See also:

OBJECTS

objects, or vertically, for ranging on See also:

HORIZONTAL

horizontal targets.

For instance, in the See also:

DIAGRAM

diagram (fig. 5) of a road See also:

RUNNING

running uphill, the instrument could be held in any of the three positions indicated, b and would give See also:

GOOD, JOHN MASON (1764-1827)

good ranges, but probably the best range would be obtained if held as at c. If it is required to use the instrument FR/POO See also:

BAR Instrument closed.

End of Article: FYE

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