25

('.- 3a

All figures on above sketch are in links/

4—C. 3a.

Subject 4.— Dealing with Old Workings and other Sources of Danger. 1. In working towards the rise in the direction of the old workings of an adjoining colliery containing a large volume of water, what check surveys or measurements would you take if doubtful as to accuracy of information obtained from old working-plans, and what other practical precautions would you insist upon ? 2. If required to carry a main-haulage road through old workings much fallen, what special precautions would you adopt to insure the safety of men employed on the work ? Show by sketches the system of timbering you would apply to fallen ground. 3. Under what conditions would you consider it necessary to withdraw miners from their workingplaces ? 4. What special precautions would you take in reopening an old mine ? Subject s.— Steam Boilers and Engines used- about Mines. 1. Say what type of boiler you consider best for colliery-work, and say where a boiler is most likely to give way from corrosion or other causes. How often should a boiler be cleaned and thoroughly examined ? 2. If the safety-valve of a boiler is 4£ in. diameter, the lever 35 in. long to the centre of the weight and 4| in. from the fulcrum to the centre of the valve, the weight being 78 lb., what is the pressure per square inch ? Show calculation. 5. What is the object of applying a condenser to a steam-engine ? What are the advantages, and what amount of vacuum would you usually expect to obtain ? Subject 6. — Mine Drainage and Haulage, and Appliances for Same. 1. What are the relative advantages and disadvantages of pumping-engines fixed above and below ground ? What plan would you adopt if required to raise 200 gallons of water per minute from each of two mines 100 yards and 200 yards deep respectively ? 2. Describe the class of pump you would use for dealing with a large quantity of water in a- sinking shaft, and show by sketches how you would fix them—the water being met with at a depth of 100 yards, and feeders likely to continue to a further depth of 100 yards. 3. Given an endless-rope haulage up a dip and operated by a friction-clutch, show by sketches the precautions you would adopt against accident from breakage of rope, breakage of clips, or from the friction-clutch being thrown out of gear. 4. A pair of winding-engines having cylinders 30 in. diameter and 5 ft. stroke and working under a steam -pressure of 60 lb. per square inch, what is the greatest diameter the drum can be made in order that the engines may raise a load of 5 tons, allowing a margin of one-third for overcoming friction ? Subject I.—Geology, Surveying, and making Plaits. 1. Describe as concisely as possible any coalfield in New Zealand with which you are acquainted. The following points should be given mention : — (a.) Nature and age of rocks forming the coal-bearing series or formation. (b.) Strike, dip, and general structure of coal-bearing rocks. (c.) Number of workable seams, their thickness, extent, and quality. (d.) Faults, rolls, washouts, &c. 2. In what way or ways do you consider coal to have been formed ?