201

a—3

Subject II. — The Various Methods adopted in securing Shafts and Workings in a Mine, showing the Relative Advantage and Efficiency of each Glass of Material used. 1. Show (with sketches) some of the various modes of setting timber in a mine, and state the advantages of each. 2. Upon what system would you work a mine liable to spontaneous combustion, and how would you deal with a gob fire in such a mine ? 3. What are the chief points to be considered in selecting a system (pillar, stall, or long-wall) in working a coal-seam ? 4. How is creep and thurst brought on, and what would you do to prevent it ? 5. Describe the mode of working thick coal-seams lying at an angle of over 40 degrees.

First Day.—Time : 2 p.m. to 5 p.m. Subject 111. — The Various Methods of hewing and cutting Goal of Different Glasses to advantage, and securing the Ground while so engaged. 1. Make a sketch of a section of stoping showing the arrangements of lifts, &c ; pillars, 30 yards by 20 yards. 2. Sketch and describe fully some methods of working narrow-edge (highly inclined) seams of coal. 3. Do you consider a pillar as strong if it has hard ribs of stone or coal and soft ones alternately as one of uniform density ? Give your reasons. 4. Enumerate the circumstances which govern the size of pillars to be left. 5. What rules should be laid down to prevent accidents from falls of roof and shot-firing? Subject IV. — The Various Methods of Ventilation, and the Construction of Airways so as to produce a Good Circulation of Fresh Air in any Part of a Mine. 1. Do changes in the barometer affect the issue of gases in the underground workings of a coalmine ? 2. Describe with sketches the construction of an air-crossing to pass 20,000 cubic feet of air per minute, giving sizes of material used. 3. What precautions are to be taken in laying out the ventilation of a coal-mine, as to length, size, and form of splits, and number of splits, crossings, doors, stopings, &c. 4. Describe with a sketch any furnace or ventilating-fan you are acquainted with, and state its advantages. 5. What methods have been proposed for detecting small quantities of gas in the air of coalmines ?

Second Day.—Time : 9 a.m. to 12 noon. Subject V. — On the Areas of Airways, the Velocity and Divisions of Currents, and the Deductions to be made for Friction. 1. If 6-horse power be required to circulate 20,000 cubic feet of air in a mine, what horsepower must be employed to pass 35,000 cubic feet through it, the airways remaining in the same condition ? 2. State the benefits from splitting the air. Where should the splits be to obtain the greatest advantage, and where should they join again? 3. In opening up a new mine where the measures have an average dip of 15°, it is proposed to work three coal-seams. State how you would open the slope and fanway and other openings, and how you would conduct your air-current. 4. What is the most effective method of dealing with firedamp in mines ? 5. Upon what does natural ventilation depend ; is it reliable, and, if not, why not ? Subject VI. — On the Nature and Composition of Explosive and Dangerous Gases occurring in Coal-mines, and on Spontaneous Combustion. 1. After an explosion of firedamp what gases result ? 2. Enumerate the noxious gases found in collieries, and state the specific gravity and composition of each. 3. Describe the principle of the safety-lamp, and the construction of one of the safest form. 4. What are the principal nitro-compounds used as explosives, and what methods have been proposed to prevent flame in the use of explosives in collieries ? 5. How does spontaneous combustion occur in coal-mines?

Second Day.—Time : 2 p.m. to 5 p.m. Subject VII. — On the Drainage of Mines, and Pumping Appliances. 1. What arrangements are necessary for renewing the wearing parts of mine-pumps and generally for keeping the pit-work in order ? 2. Explain by means of ink sketches the difference between a " force " or plunger pump and a " lifting " or bucket pump. 3. What size of pumps and engine would you erect to pump 600 gallons of water per minute from a depth of 720 ft. ? Give a general description of the engine you prefer with the principal sizes.