Page:Transactions of the Geological Society, 1st series, vol. 3.djvu/393



X. Description of a Clinometer.

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[Read May 30th, 1814.]

every description of stratified rocks the importance of determining the position of the plane of stratification, by referring it to some standard, is so obvious that to insist on it would be a needless intrusion upon the time and attention of this Society. The object of the present paper is to submit to the Society a description of an instrument contrived for the above purpose, accompanied by drawings, and to add an explanation of the method of using it. This instrument has received the name of the Clinometer.



The Clinometer consists of two parts, the plate and the quadrant. Plate 25, exhibits both lying horizontally, the quadrant in the position in which it lies packed in its case. Plate 26 shews the two parts put together, lying upon an inclined surface, and adjusted for an observation to determine its position. In both plates every part of the instrument is represented of the real size, and the references in the description are made to both by the same letters.



The plate represented by A, is circular and of brass. On the under surface, near the edge, it is thickened by a ring to give it greater strength. It is supported by three feet a a a, placed at equal distances just within the ring, and made of wood, with their ends flat and broad, of a form somewhat oval, and having its length