Online Encyclopedia

Search over 40,000 articles from the original, classic Encyclopedia Britannica, 11th Edition.

INCLINOMETER (Dip CIRCLE)

Online Encyclopedia

Originally appearing in Volume V14, Page 356 of the 1911 Encyclopedia Britannica.

» Make a correction to this article.
» Add information or comments to this article.

Encyclopedia Home :: I27-INV

Spread the word:

del.icio.us it!

See also:

INCLINOMETER (Dip CIRCLE)

INCLINOMETER (See also:
DIP (Old Eng. dyppan, connected with the common Teutonic root seen in " deep ")
Dip CIRCLE) . Two distinct classes of See also:

INSTRUMENTS

instruments are used for measuring the dip (see See also:

MAGNETISM, TERRESTRIAL) or inclination of the See also:

earth's magnetic See also:

field to the See also:

HORIZONTAL

horizontal, namely (I) dip circles, and (2) See also:

INDUCTION (from Lat. inducere, to lead into; cf. Gr. ilrayu yli)

induction inclinometers or earth inductors. Dip Circles.—In the See also:

case of the dip circle the direction of the earth's magnetic field is obtained by observing the position of the See also:

AXIS (Lat. for " axle ")

axis of a magnetized See also:

NEEDLE (O. Eng. ncedl; the word appears in various forms in Teutonic languages, Ger. Nadel, Dutch naal, the root being ne-, to sew, cf. Ger. nahen, and probably Lat. nere, to spin, Gr. vi)ats, spinning)

needle so supported as to be See also:

FREE

free to turn about a horizontal axis passing through its centre of gravity. The needles now used consist of See also:

FLAT (a modification of O. Eng. flet, an obsolete word of Teutonic origin, meaning the ground beneath the feet)

flat See also:

LOZENGE (from the Fr. losenge, or losange; the word also appears in Span. losanje, and Ital. losanga; perhaps derived from a word meaning a stone slab laid on a grave, which appears in forms such as Provencal lousa, Span. losa, the ultimate origin of whic

lozenge-shaped pieces of See also:

STEEL, FLORA ANNIE (1847– )

steel about 9 cm. See also:

long and 9.1 cm. thick, and weigh about 4'1 grams. The See also:

AXLE (in Mid. Eng. axel-tre, from O. Norweg. oxull-tre, cognate with the O. Eng. exe or eaxe, and connected with Sansk. dksha, Gr. a wv, and Lat. axis)

axle, which is made of hard steel, projects on either See also:

side of the needle and has a See also:

DIAMETER (from the Cr. &a, through, µErpov, measure)

diameter of about 0.05 cm. Needles considerably larger than the above have been used, but experience showed that the values for the dip observed with needles 23 cm. long, was about 1' less than with the 9 cm. needles, and A. Schuster (Phil. Mag., 1881 (5], 31, p. 275) has shown that the difference is due to the appreciable bending of the longer needles owing to their See also:

WEIGHT

weight. - When in use the dip needle is supported on two See also:

AGATE

agate See also:

KNIFE (0. E. cuff, a word appearing in different forms in many Teutonic languages, cf. Du. knijf, Ger. Kneif, a shoe-maker's knife, Swed. knif; the ultimate origin is unknown; Skeat finds the origin in the root of " nip," formerly " knip "; Fr. canif is a

knife= edges, so that its axle is on the axis of a See also:

VERTICAL (from Lat. vertex, highest point)

vertical divided circle, on which the positions of the ends of the needle are either directly observed by means of two See also:

READING

reading lenses, in which case the circle is generally divided into thirds of a degree so that it can by estimation be read to about two minutes, or a See also:

CROSS

cross 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 carries two small microscopes and two verniers, the cross wires of each See also:

MICROSCOPE (Gr. µucp6s, small, asenreiv, to %view)

microscope being adjusted so as to bisect the See also:

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

image of the corresponding end of the needle. Two V-shaped lifters actuated by- a handle serve to raise the needle from the agates, and when lowered assure the axle being at the centre of the vertical circle. The supports for the needle, and a See also:

box to protect the needle from See also:

DRAUGHTS (from AS. dragan, to draw)

draughts, as well as the vertical circle, can be rotated about a vertical axis, and their See also:

AZIMUTH (from the Arabic)

azimuth read off on a horizontal divided circle.

There are also two adjustable stops which can be set in any position, and allow the upper See also:

PART

part of the See also:

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

instrument to be rotated through exactly 1800 without the See also:

NECESSITY (Lat. necessitas)

necessity of reading the horizontal circle. When making a determination of the dip with the dip circle, a number of See also:

SEPARATE

separate readings have to be made in See also:

order to eliminate various instrumental defects. Thus, that side of the needle on which the number is engraved being called the See also:

FACE (from Lat. fades, derived either from facere, to make, or from a root fa-, meaning " appear "; cf. Gr. cbatvstv)

face of the needle, and that side of the protecting box next the vertical circle the face of the instrument, both ends of the needle are observed in the following relative positions, the instrument being in every case so adjusted in azimuth that the axle of the needle points magnetic See also:

east and See also:

west: i. Face of instrument east and face of needle next to face of instrument; ii. Face of instrument west and face of needle next to face of instrument; iii. Face of instrument west and face of needle away from face of instrument; iv. Face of instrument east and face of needle away from face of instrument. Next the direction of magnetization of the needle is reversed by stroking it a number of times with two strong permanent magnets, when the other end of the needle dips and the above four sets of readings are repeated. The See also:

OBJECT

object in reading both ends of the needle is to avoid See also:

ERROR (Lat. error, from errare, to wander, to err)

error if the prolongation of the axle of the needle does not pass through the centre of the vertical circle, as also to avoid error due to the eccentricity of the arm which carries the reading microscopes and verniers. The reversal of the instrument between (i.) and (ii.) and between (iii.) and (iv.) is to eliminate errors due to (a) the See also:

LINE

line joining the zeros of the vertical circle not being exactly horizontal, and (b) the agate knife-edges which support the needle not being exactly horizontal. The reversal of the needle between (ii.) and (iii.) is to eliminate errors due to (a) the magnetic axis of the needle not coinciding with the line joining the two points of the needle, and (h) to the centre of gravity of the needle being displaced from the centre of the axle in a direction at right angles to the length of the needle. The reversal of the poles of the needle is to counteract any error produced by the centre of gravity of the needle being displaced from the centre of the axle in a direction parallel to the length of the needle.

For use at See also:

sea the dip circle was modified by See also:

Robert Were See also:

Fox (See also:

ANNALS (Annales, from annus, a year)

Annals of See also:

ELECTRICITY

Electricity, 1839, 3, p. 288), who used a needle having pointed axles, the points resting in jewelled holes carried by two uprights, so that the See also:

MOVEMENT

movement of the See also:

SHIP

ship does not cause the axle of the needle to See also:

CHANGE (derived through the Fr. from the Late Lat. cambium, cambiare, to barter; the ultimate derivation is probably from the root which appears in the Gr. «a urmu', to bend)

change its position with reference to the vertical divided circle. To counteract the tendency of the axle to stick in the See also:

BEARINGS

bearings, the instrument is fitted with a knob on the See also:

TOP (cf. Dan. top, Ger. Topf, also meaning pot)

top of the box protecting the needle, and when a reading is being taken this knob is rubbed with an See also:

ivory or See also:

horn disk, the See also:

SURFACE

surface of which is corrugated. In this way a tremor is caused which is found to assist the needle in overcoming the effects of See also:

FRICTION (from Lat. fricare, to rub)

friction, so that it takes up its true position. In the Creak modification of the Fox dip circle, the upper halves of the jewels which See also:

FORM (Lat. forma)

form the bearings are cut away so that the needle can be easily removed, and thus the reversals necessary when making a See also:

COMPLETE

complete observation can be performed (see also MAGNETO-See also:

METER, ELECTRIC

METER). Induction Inclinometers.—The principle on which induction inclinometers depend is that if a coil of insulated See also:

WIRE (A.S. wir, a wire; cf. Swed. vire, to twist, M.H.G. wiere, a gold ornament, Lat. viriae, armlets, ultimately from the root wi, to twist, bind)

wire is spun about a diameter there will be an alternating current induced in the coil, unless the axis about which it turns is parallel to the lines of force of the earth's field. Hence if the axis about which such a coil spins is adjusted till a sensitive See also:

GALVANOMETER

galvanometer connected to the coil through a commutator, by which the alternating current is converted into a See also:

DIRECT

direct current, is undeflected, then the axis must be parallel to the lines of force of the earth's field, and hence the inclination of the axis to the horizontal is the dip. The introduction and perfection of this type of inclinometeris almost entirely due to H. See also:

WILD, JONATHAN (c. 1682-1725)

Wild. His form of instrument for field observations' consists of a coil ro cm. in diameter, containing about See also:

ROOD (O.E. rod, a stick, another form of " rod, O.E. rodd, possibly cognate with Lat. rudis, a staff)

rood turns of See also:

SILK

silk-covered See also:

COPPER (symbol Cu, atomic weight 63.1, H=1, or 63.6, O = 16)

copper wire, the resistance being about 40 ohms, which is pivoted inside a See also:

metal See also:

RING (O.E. hring; a word common to Teutonic languages; and probably cognate with the Lat. circus, Gr. KtpKOS or KpLKOS, Skt'. chakra, wheel, circle, cf. also " harangue "); in art, a band of circular shape of varying sizes, made of any material and used f

ring. This ring can itself rotate about a horizontal axle in its own See also:

PLANE

plane, this axle being at right angles to that about which the coil can rotate. Attached to the axle of the ring is a divided circle, by means of which and two reading microscopes the inclination of the axis of rotation of the coil to the horizontal can be read.

The bearings which support the horizontal axle of the ring are mounted on a horizontal annulus which can be rotated in a groove attached to the See also:

BASE

base of the instrument, as so to allow the azimuth of the axle of the ring, and hence also that of the plane in which the axis of the coil can move, to be adjusted. The coil is rotated by means of a flexible See also:

shaft worked by a small cranked handle and a See also:

TRAIN (M. Eng. trayn or trayne, derived through Fr. from Late Lat. trahinare, to drag, draw, Lat. trahere, cf. trail, trace, ultimately from the same source)

train of See also:

GEAR (connected with " garb," properly elegance, fashion, especially of dress, and with " gar," to cause to do, only found in Scottish and northern dialects; the root of the word is seen in the Old Tent. garwjan, to make ready)

gear wheels. The terminals of the coil are taken to a two-part commutator of the See also:

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

ordinary See also:

PATTERN

pattern on which See also:

REST (O. Eng. rest, reste, bed, cognate with other Teutonic forms, e.g. Ger. Rast, Riiste, rest, and probably Gothic Rasta, league, i.e. resting or stopping place)

rest two copper brushes which are connected by flexible leads to a sensitive galvanometer. The inclination of the axis of the coil can be roughly adjusted by See also:

hand by rotating the supporting ring. The final See also:

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

adjustment is made by means of a See also:

MICROMETER (from Gr. wcp6c, small, jArpov, a measure)

micrometer See also:

SCREW (O.E. scrue, from O. Fr. escroue, mod. ecrou; ultimate origin uncertain; the word, or a similar one, appears in Teutonic languages, cf. Ger. Schraube, Dan. skrue, but Skeat, following Diaz, finds the origin in Lat. scrobs, a ditch, hole, particularl

screw attached to an arm which is clamped on the axle of the ring. When making a measurement the azimuth circle is first set horizontal, a striding level placed on the trunnions which carry the ring being used to indicate when the adjustment is complete. The striding level is then placed on the axle which carries the coil, and when the bubble is at the centre of the See also:

scale the micro-scopes are adjusted to the zeros of the vertical circle. A box containing a long See also:

COMPASS (Fr. corn pas, ultimately from Lat. cum, with, and passus, step)

compass needle and having two feet with inverted V's is placed to rest on the axle of the coil, and the instrument is turned in azimuth till the compass needle points to a lubber line on the box. By this means the axis of the coil is brought into the magnetic See also:

meridian. The commutator being connected to a sensitive galvanometer, the coil is rotated, and the ring adjusted till the galvanometer is undeflected. The reading on the vertical. circle then gives the dip. By a See also:

SYSTEM

system of reversals slight faults in the adjustment of the instrument can be eliminated as in the case of the dip circle.

With such an instrument it is claimed that readings of dip can be made accurate to o•1 minutes of arc. The form of Wild inductor for use in a fixed See also:

OBSERVATORY

observatory differs from the above in that the coil consists of a 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-See also:

WOUND (O. Eng. wund,connected with a Teutonic verb, meaning to strive, fight, suffer, seen in O. Eng. winnan, whence Eng. " win ")

wound See also:

ARMATURE (from Lat. armatura, armour)

armature, but without See also:

IRON [symbol Fe, atomic weight 55.85 (0=16)]

iron, of which the length is about three times the diameter. This armature has its axle mounted in a See also:

FRAME

frame attached to the sloping side of a See also:

stone See also:

PILLAR (0. Fr. piler, Mod. pilier, Late Lat. pilare, from pila, column)

pillar, so that the axis See also:

cos rotation is approximately parallel to the lines of force of the earth's field. By means of two micrometer screws the inclination of the axis to the magnetic meridian and to the horizontal can be adjusted. The armature is fitted with a commutator and a system of gear wheels by means of which it can be rapidly rotated. The upper end of the axle carries a plane See also:

MIRROR (through O. Fr. mirour, mod. miroir, from a sup-posed Late Lat. miratorium, from mirari, to admire)

mirror, the normal to which is adjusted parallel to the axis of rotation of the armature. A See also:

THEODOLITE

theodolite is placed on the top of the pillar and the See also:

TELESCOPE

telescope is turned so that the image of the cross-wires, seen by reflection in the mirror, coincides with the wires themselves. In this way the axis of the theodolite telescope is placed parallel to the axis of the armature, and hence the dip can be read off on the See also:

ALTITUDE (Lat. altitudo, from altus, high)

altitude circle of the theodolite. 1 Repertorium See also:

FUR (connected with O. Fr. forre, a sheath or case; so " an outer covering ")

fur Meteorologic der kaiserl. Akad. der Wissensch. (St See also:

PETERSBURG

Petersburg, 1892), 16, No. 2, or Meteorolog.

Zeits. (1895), 12, p. 41.

End of Article: INCLINOMETER (Dip CIRCLE)

Additional information and Comments

There are no comments yet for this article.

» Add information or comments to this article.

Please link directly to this article:
Highlight the code below, right click, and select "copy." Then paste it into your website, email, or other HTML.

Site content, images, and layout Copyright © 2006 - Net Industries, worldwide.
Do not copy, download, transfer, or otherwise replicate the site content in whole or in part.

Links to articles and home page are always encouraged.

[back]
INCLEDON, CHARLES BENJAMIN (1763–1826)

[next]
INCLOSURE, or ENCLOSURE