KLINOMETER, or Clinometer (from xajvω, which denotes inclination, and μsrgov), the name of an instrument contrived by the late Lord Webb Seymour, a nobleman who devoted his life to the cultivation of science. This instrument is intended to be used by the geologist for measuring the inclination of stratified rocks, and the azimuth in which that inclination lies.

If a plummet-level be applied to an inclined plane in that position in which the edge or base of the plumnιet-level is horizontal, and if the edge of the plummet-level be then turned round ninety degrees in the inclined plane, the angle formed by the plumb-line with the line which is perpendicular to the edge of the plummet-level is equal to the inclination of the inclined line to the horizon. On the same principle the inclination of a plane to the horizon is measured by the klinometer.

In the klinometer represented at Plate XCIV. fig. I, AC is a circular plate, the circumference of which is divided into 360 degrees; it has three short íëet on its under surface, one of which is seen at S.

The feet on, the under side of the plate are of wood, which is preferred to metal, as less liable to slip when placed on an inclined surface. The ends of the feet are in a plane parallel to the upper surface of the circular plate. The fibre of the wood is set perpendicular to the plate, to diminish the derangement which may happen by the expansion of the wood from moisture.

The arm CG is moveable round the centre of the circular plate. D is an oval hole, through which is moveable the catch of a sliding bolt; this bolt passes on the under side of the circular plate; the catch of the bolt is made flush with the surface of the circular plate. The bolt serves to fix the arm CG ou the circular plate. When the [7:12:744]instrument is to be used, C is the axis round which the arm CG turns. When the three short feet of the circular plate are placed on the inclined surface of a stratified rock, the arm which bears the spirit level EE is moved down to the lowest point of the quadrant DD, and the arm CG is moved round till the bubble stands in the middle of the level; the arm CG and the level are then in the intersection of the inclined stratum with a plane parallel to the horizon: the degree on the edge of the circular plate at which the arm CG now stands is noted, and the arm CG is to be moved round through ninety degrees of the circular plate upwards; when the arm CG is arrived at this second position, it is in the line of the greatest inclination of the stratified rock. The arm which bears the spirit level EE is then to be raised, by turning it on the centre of the quadrant; and when the bubble stands in the middle of the level, the arm will indicate, on the limb of the quadrant, the degree of inclination of the stratified rock. The magnetic needle in the box 00 will, at the same time, show the magnetic azimuth, formed by the vertical plane, which contains the angle of greatest inclination; and this magnetic azimuth is to be converted into true azimuth by applying the number of degrees that the needle varies from the true meridian, at the particular time and place where the observation is made. The box OO has both the top and the bottom made of glass, so that the needle may be observed both when the instrument is placed on the upper surface, and when the instrument is applied to the under surface, of an inclined plane. When the instrument is not in use, the arm CG, with the quadrant and compass, are unfixed, and taken off from the circular plate, by withdrawing the catch of the bolt which is seen at d. The compass-box 00 is turned round an axis, which is seen below the spirit level EE, so that the compass-box comes into the same plane with the quadrant, and then the quadrant, compass-box, and arm, CG, pack into a flat box. The circular plate ACS is now separate from the other parts of the instrument, and lies flat in another part of the box made for packing the instrument. Lord Webb Seymour’s account of this instrument is published in the Transactions of the Geological Society, vol. iii. 1816.