xv BOI !M>OOR-\VOkK in 



instead of a geological diagram is so great that the 

 1 Acid-work suffers diminution. Hence I would 

 that the field-work be done first, and that the 

 observer, having thus been over the ground and chosen 

 his points of view, should return with his sketch-book 

 <>lour-box, and use them with no inward conscious- 

 ness that he ought to be up and wielding his hammer. 

 An occasional thoroughly wet day, when work out of 

 doors is impossible, affords an excellent opportunity for 

 he drawings, rocks, drawing sections, 



< up notes, and indeed for all other kinds of in- 

 door employment. 



hapter I spoke of certain jxmions of his 

 labours which the field-geologist could only accomplish 

 within doors. I propose now to describe three kinds of 

 indoor- work, (i) Section-drawing; (2) chemical and 

 mechanical testing of rocks ; and (3) the examination of 

 rocks with the microscope. 



SBCTtON-DRAv, 



construction of geological sections is placed here 

 among the indoor employments of the field-geologist, 

 although if they are to be as full and perfect as possible, 

 their outlines must be traced on the ground. A section 

 on a true scale, vertical and horizontal, may be prepared 

 hv measurement on the ground in the ordinary way with 

 chain and theodolite. Hut this is an operation of 

 ordinary land need not be described 



here. Or if the country has been accurately contoured, 



