June 20.] THE NEW ZEALAND GAZETTE. 1889

213. Where, by preference, should the escape-valve of a feed-pump be placed? Why?

214. Scum-cocks are sometimes fitted to boiler-shells at a height convenient for engineers to manipulate when standing in the stokehold; the scum-pipes in such cases are led upward, inside the boiler, to a little above the combustion-chamber tops: what danger may arise from this arrangement?

215. Cocks for testing the water-level of boilers are sometimes fitted within reach of the engineer who is standing in the stokehold; these may have internal pipes leading upward and terminating at various levels: under what circumstances may these become misleading?

216. Why should the pipe which leads from the bottom of the water-gauge column to the bottom of the boiler-front, or back, be covered with non-conducting material? Why, also, should it never have lengthy horizontal bends?

217. In your own experience, how frequently is this pipe removed and cleared?

218. Why, even with the best of water-gauges, is it advisable to occasionally use the drain-cock?

219. Steam-loops have sometimes been inadvertently made in the length of piping leading from the top of the water-gauge column to the top of the boiler: roughly sketch such a loop, and explain the danger arising from its existence.

220. Describe your method of thoroughly testing the water-gauge system to satisfy yourself that all the cocks and pipes are clear. [Your answer can be written on a supplementary sheet of foolscap, which the Examiner will hand you. Hand-sketches, mere lines indicating pipes and circles indicating cocks, should be made. Identify the cocks and pipes by letters or numerals.]

221. Describe the construction of a water-tube boiler, mentioning the type selected.

222. In a water-tube boiler, how is an economizer fitted, and what is its duty?

223. How is the water-gauge fitted? Are glass gauges used?

224. The pressure of the steam in water-tube boilers is sometimes greater than at the engines: why is this, and what percentage above the engine-pressure does it amount to? How is this difference of pressure maintained?

225. Describe any automatic method of feeding water-tube boilers. Of what materials are the tubes made?

226. Describe the construction of any steam-turbine you are acquainted with which is used on board ship. How is the expansion of steam effected? How many propeller-shafts are employed, and how many propellers?

227. Is the same power available to go astern as to go ahead?

228. Of what material are the propellers made?

229. How many pounds of coal per indicated horsepower per hour are burnt with this type of engine? Name the type of boiler in use.

230. Describe one of the several classes of refrigerating machinery in use on board of ship. Several types exist, one being more economical than the rest: which is it?

231. Describe the defects to which the selected type is subject. How are the defects overcome?

232. How frequently are the parts opened out for examination? Name the parts.

233. How frequently are the condensers of refrigerating plants opened for examination? How frequently are the coils tested by hydraulic pressure? On which side of the coil is corrosion most commonly found? Why should this be so?

234. Where ammonia is used in refrigerating machinery, should the machinery by preference be isolated? Why? In reply, give what information you possess bearing on the matter, naming the ships for purposes of identification.

235. Explain how the ammonia is removed from the tubes in which it is supplied, and how passed into the refrigerating-machine.

236. What objection is there to the presence of water in the ammonia?

237. Describe the ammonia process of refrigeration.

238. Of what material are the parts made which are in contact with the ammonia?

239. Are escape-valves fitted to the compressors of ammonia-machines?

240. What is the maximum pressure found in the compressors of ammonia-machines?

241. What kind of pressure and other gauges are used in ammonia machines?

242. Explain how carbonic acid is removed from the tubes in which it is supplied, and how passed into the refrigerating-machine?

243. What objection is there to the presence of water in the carbonic acid?

244. Describe the carbonic-acid process of refrigeration.

245. Of what material are the parts made which are in contact with the carbonic acid?

246. Are escape-valves fitted to the compressors of carbonic-acid machines?

247. What is the maximum pressure found in the compressors of carbonic-acid machines?

248. What kind of pressure and other gauges are used in carbonic-acid machines?

249. In which type of machine is brine used? What is its density? Where does it circulate?

250. Are fans for circulating air used in any of these processes? If yes, why are they necessary?

251. What means are in some cases employed for ascertaining the temperatures of refrigerating-chambers without entering them?

252. What effect may the swabbing of the compressor piston-rods have upon the working of refrigerating machinery?

253. What is a rectifier? Explain its use.

254. Describe the cold-air process of refrigeration.

255. Of what material are the air-suction and delivery valves made? How are the valves kept on their seats?

256. How many compressors are there to a cold-air machine?

257. What is the duty of the expansion cylinder of a cold-air machine?

258. What objection is there to the presence of moisture in the air passed through the cold-air machine?

259. How is water to some extent removed from the air? What is the minimum temperature of the air?

260. What is the maximum pressure found in the compressors of cold-air machines?

261. What kind of pressure and other gauges are used in cold-air machines?

262. In refrigerating-engines generally, to where is the exhaust steam led?

263. Cold-air chambers on board ship are insulated: how insulated, and why?

264. Is it prudent to allow the wires of an electric circuit to pass through the insulation? Explain fully.