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Subject C.— The Ventilation of Mines and Composition of Gases. 1. What is meant by "ventilation" in mines 1 Why is it required '( How is it produced '{ Explain fully. 2. Give the symbols, specific gravity, and composition of gases met with in mines, and explain how the presence of these gases is detected. 3. If the workings in a mine contained 1,000,000 cubic feet of air, of which 5 per cent, was CO 2 , how much atmospheric air would be required to dilute the air in the mine to render it harmless to workmen ? 4. How can the presence of CO 2 be detected m a mine ? What is the lowest percentage that can be detected ? What effect has it on the workmen ? Explain fully. 5. How is natural ventilation effected, and also how is ventilation effected by mechanical means % 6. The openings into a mine are by two shafts, each having a cross-sectional area of 100 square feet; the air in the downcast shaft has a temperature of 60° Fahr., and the air in the upcast shaft has a temperature of 87° Fahr. : show by calculation the ventilating-power. Subject D. — Tapping Water in Mines, and. the Mode of constructing Dams in Underground Workings to keep the Water back. 1. In sinking a shaft, when at a depth of 100 ft. you encounter a layer of porous rock containing water ; the layer is 20 ft. thick : what steps would you take to prevent the water getting down the shaft as the sinking proceeds ? Describe fully. 2. It is desired to use an old crosscut (at a depth of 300 ft.) as a dam for collecting all the water from this level to the surface, and so to prevent the water getting down the shaft to the 1,000 ft. level ; the crosscut is 7 ft. by 5 ft. ; the water is to be dammed back to a height of 4 ft. : show how you would construct the breastwork ; and what material would you use ? 3. A dam is to be constructed in a crosscut to old workings ; the rock is solid ; the water wili rise 600 ft. above the dam :|give sketch of construction of dam, and show by calculation the total pressure on the structure ; give details, the material you would use, and why. 4. At 400 ft. in depth from collar of shaft a level was constructed on a down grade of 5-J in. per chain for a distance of 600 ft. ; the water was then allowed to accumulate antil it rose 40 ft. above the chamber ; at this stage a tannel driven from the opposite side of the hill (to meet the level from shaft) was 3,000 ft. in length, and (by survey) was found to be within 20 ft. of meeting : explain fully the steps you would now take to insure the perfect safety of the workmen when the connection was made. 5. A winze was sunk 100 ft. and timbered with black-birch ; it was then allowed to stand until the water rose to the top of winze ; ar uprise to connect with the bottom of the winze is withii 25 ft. : explain fully the precautions (if any) that you would now take to insure the safety of the workmen before you broke through to the bottom of the winze. Subject E. — Blasting, and the Use of Explosives. 1. Give relative strengths of blasting-gelatine, gelignite, rackarock, and dynamite, taking blastingpowder as TOO ; also give the composition of each. 2. Show by sketch how you would fire eight holes simultaneously with Bickford's igniter. 3. In case of a misfire, what time would you allow to elapse before going back, and what kind of pricker (if any) would you use ? 4. If a charge of blasting-gelatine requires ten ordinary plugs, how many plugs of gelignite would you use for the same charge ? 5. How do you fashion both ends of your scraper ? 6. Out of what material do you make your tamping-bar ? 7. When in a frozen condition, does blasting-gelatine become less powerful '( If not, would you use it without thawing ? If you thawed it, how would you do it ? 8. Give weight and composition of charges in Nobel's Nos. 3, 6, and 7 detonators respectively. 9. Suppose you charged three holes, one each with dynamite, gelignite, and blasting-gelatine, what number of the above detonators would you use for each ? 10. With what weight of blasting-gelatine would you charge a hole in medium-hard rock where the hole is 4 ft. 6 in. deep, and the line of least resistance is 2 ft. 9 in. ? Show how you arrive at it. Subject F.— A Knowledge of Arithmetic and the Method of keeping Mining Accounts. 1. Five samples were assayed from a quartz lode —namely, 2 ft. in width gave 16 dwt. 13 gr. of gokTto the ton ; 3 ft. gave 7 dwt. 23 gr. ; 4 ft. 9 in. gave 8 dwt. 4 gr. ; 1 ft. 7 in. gave 34 dwt. J gr. ; 2 ft. 6 in. gave 17 dwt. : show by calculation the average value of the cross-section of the lode where the samples were taken from, taking the value of the gold to be £3 13s. 4d. per ounce.