Helping San Diego, California and beyond since 1997.
Do you need
volunteer, community service, work, military or court hours?
|
|
Helping San Diego, California and beyond since 1997.
|
|
Click here and add this page to your favorites!
|
Encyclopedia Britannica - Main :: FRA-GAE |
|
|
FYE PIEOES OEFLECFIRG PRISM OBJECT GLASS REFLECTOR in length), in which of error. For field artillery, however, a range-finder is only an auxiliary
elevation
auxiliary
RANGE-FINDER and passing through the object-glasses, each is received by an arrangement of prisms about the centre of the tube, and reflected through the right eye-piece. Two partial images are thus seen. The images could be united by the rotation of one of the reflectors, but owing to the small base used the necessary movement
instrument is not affected by back lash arising from wear, or irregularity in the actuating mechanism. When once installed, the instrument is always ready for use. Should adjustment be required it is readily and easily applied. It is not within the sphere of this article to enter into the detail of the adjusting mechanism. For further particulars the reader is referred to the Proceedings of the Institution of Mechanical Engineers, 30th January 1896. The working of the range-finder is so simple that its use is quickly learnt by any 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 minor uses in navigation and nautical surveying to which the range-finder can' be applied.With the high speeds of modern war-vessels, guns and their 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 naval range-finder an apparatus is provided, which though not part of the range-finder is sufficiently important to claim passing notice. The apparatus consists of a transmitting and a receiving instrument of clockwork mechanism electrically controlled. In appearance they resemble the ordinary engine
2. Before the introduction of the Marindin range-finder described below, the British army in the field used the " mekometer." The instruments used by the cavalry and infantry are smaller and lighter than those of the artillery pattern, but the principle involved is identical. The mekometer is practically a box sextant
sextant
measures
Two observers attach the ends of the cord of fixed length (usually 50 yds.) to their instruments and separate until it is taut. The Meko- observer with the right-angle instrument moves into such meter
the objective and the vane of the instrument at the other end of the base, i.e. he makes 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
The mekometer is open to the objection which is 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 Captain A. H. Marindin, of the Black Watch (Royal Highlanders). The principle of the instrument is that of coincidence, as in the Gautier Christie, Le Cyre, Souchier, and Barr and Stroud. But it differs from the last mentioned in that the right prism is made movable, and this movement
The steel tube, forming the base of the instrument, which carries the prisms,is supported inside an aluminium outer tube in such a way that no direct 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 main positions, viz. horizontally, Instrument ready for use. FIG. 4.-Marindin Range-Finder. for ranging on upright objects, or vertically, for ranging on horizontal
For instance, in the diagram (fig. 5) of a road running uphill, the instrument could be held in any of the three positions indicated, b and would give 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 BAR Instrument closed. EYEPIECE End of Article: FYE If you wish, you can link directly to this article.
<a href="http://jcsm.org/StudyCenter/Encyclopedia/FRA_GAE/FYE.html"> FYE </a> |
|
|
(Previous) FUZE |
(Next) FYNE, LOCH |
|
Sponsored Advertisements