LLUSTRATIONS. 



PLATES. 



Page. 



PLATE I. Fig. 1. Basalt (Trap). Fig. 2. Diabase (Trap) 77 



II. Fig. 1. Gabbro (Trap) . Fig. 2. Diorite (Trap) 77 



III. Fig. 1. Gneiss. Fig. 2. Mica-schist 77 



IV. Fig. 1. Quartzite. Fig. 2. Limestone 77 



V. Fig. 1. Granite. Fig. 2. Syenite 77 



TEXT FIGURES. 



FIG. 1. Abrasion machine 18 



2. Dorry machine for determining hardness 20 



3. Ball mill 27 



4. Briquette die 28 



5. Briquette machine 29 



6. Impact machine to determine cementing value of rock 30 



7. Diagram showing point of failure in cementation test 31 



S. Impact machine for determining toughness 34 



9. Brick rattler 37 



10. Core drill 



4 



