386 Lord Webb Seymour on a Clinometer. 



in the direction of the margin. Wood is preferred to metal for 

 the feet, as less likely to slip on a smooth surface ; and they are 

 made broad at the end, to prevent the position of the plate and 

 the firmness of its rest from being too much affected by the minute 

 inequalities of a rough one. The flat ends of the feet are adjusted 

 to a plane parallel to the upper surface of the plate ; and the fibre 

 of the wood is set perpendicularly, in order to prevent any derange- 

 ment from the expansion and contraction of the wood attending 

 the changes of moisture. On the upper surface near the edge, is 

 a circle divided into degrees, which are numbered from zero to 90" 

 through the four quarters successively in the Same order ; and it 

 is of no consequence whether this is done from left to right, or 

 from right to left. In the center of the plate is a circular hole b^ 

 to receive an axis on the under side of the base of the quadrant. 

 For securing it, there is a bolt cc^ which slides below, and is 

 worked by a catch d rising through an oval hole in the plate and 

 made flush with its surface. 



B represents the quadrant, which has all its frame-work of brass. 

 CC is its base, which traverses upon the plate ; at <? is the button 

 of the central ^xis, which is secured in the center of the plate by 

 the hollowed end of the bolt beneath, and at /'is the clamp and 

 milled-head screw, for fixing the quadrant to the edge of the plate 

 in any direction. At / is a rectangular aperture, through which 

 the divisions of the plate are seen, and read off by an index on rhe 

 •middle of the bevelled side of the aperture nearest to the central 

 axis. D D is the graduated arch, fixed firmly to the base, and at 

 right angles to the plane of its under surface. It is divided into 

 degrees, which are numbered from below. At h i« the head of a 

 short axis passing through the center of the arch, and revolving 

 w'uh the motion oi the radial bar m 7W, which carries with it the 



