26 OUTLINES OF PIELD-GBOLOt PA. 



in tin- < linom< a-pt to get broken. A nun h 



more portable and serviceable 1'nrm <>i < lit. ,,y In- 



made by the geologist himself. It consists of two thin 

 leaves of wood, each two inches broad and six inches 

 long, neatly hinged together, so as to open out and form 

 a foot rule when required. On the inside of one of these 

 a small brass pendulum is so fixed that when it 

 swings freely and hangs vertically, it forms an angle of 90, 

 with the upper edge of the leaf to which it is attached. 

 An arc, graduated to 90 on each side of the \vrtical. is 

 drawn on the wood, or on paper or brass fastened to the 

 wood, so that when the leaf is moved on either side, the 

 exact number of degrees of inclination is shown by the 

 pendulum on the graduated arc. The corresponding face 

 of the opposite leaf is hollowed out just enough to let the 

 two leaves fit closely, and keep the pendulum in its pi act- 

 when the instrument is not in use. This form of clino- 

 meter, made of boxwood and bound with brass, may be 

 obtained of instrument makers. 1 It is light and strong, 

 and its durability may be understood from the fact that 

 the instrument which I carry in the field has been in use 

 for more than forty years. 



If at any time the geologist has occasion to lighten 

 his equipment for some long mountain expedition, where 

 every additional ounce of weight begins to tell by the 

 end of the day, and where, therefore, for the sake of 

 doing as much and holding out as long as possible, he 



1 This and the other instruments referred to in the text may l>e 

 obtained from Troughton an<l Simms, London ; Turnhull ai 

 Edinburgh ; Robinson and Sons, Dublin : or from any of the numerous 

 dealers in minerals now to be found in this country and abroad. 



