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tion, the hotwell pumps are controlled by float gear in the hotwell tanks-- the latter, in case of a shortage of water supply, to prevent the pumps running away, and the former preclud- ing the possibility of water being forced back to the _ turbo-genera- tors, should the non-return valve in the steam inlet to the contact heater fail to act in the. event of the feed pumps suddenly slowing. In most merchant ships, on account of accidents which have occurred, it "has been the general practice to lead the exhaust from the electric engines direct to the main or auxiliary con- densers only, to ensure steady run- ning of the dynamos and to prevent the possible passing back of water from other auxiliary engines into the cylinders of the electric engines. In this present case the electric installa- tion is so large, and the temperature of the hotwell, due to the high vacuum maintained, so low, that it was con- sidered to be essential to utilize 'this exhaust for the heating of tthe feed water, and, by adopting this duplicate system of feed heaters and hotwell control, this end has been attained with a minimum of risk. Owing to the very great length of feed supply pipes from the feed pumps to the forward boilers, there was considerable speculation as to whether the feed supply to each boiler room would have to be entirely dis- tinct. Had this been so, each pair of feed pumps would have required to be worked entirely independently of the others, and, in the event of any hitch occuring, one of the two pairs of stand-by pumps would have had to be at once connected to the par- ticular boiler room in question. In actual running, however, that the four main feed supply pipes could be cross-connected and made common, thus making any demand for Special care and te on this score unnecessary. With regard to the maintenance of 'steady steam at sea, although innumer- able types of rocking and self-cleaning firebars have been devised and tried in connection with automatic. stokers, none of these has been found to give Satisfactory results in merchant ves- sels. The stoking, and especially the cleaning of the fires" wherever. hard... steaming is required, is the same as it was! 50 years ago, and, as a conse- saen Ce, is dependent on. the willing- 'fess afid ability of each unit of the king complement cof the ship. ~The' following hourly abstract on e of the watches on the Lusitania tings home to one's mind the loss it was found- TAE MARINE REVIEW in steam and speed caused by clean- ing fires, especially when the coal is small. It can easily be calculated from this what an appreciable increase in the ship's mean speed could be ob- tained from this cause alone, if the price and supply would admit of the use of some system of oil fuel burning. Mean Corresponding 2 revolutions. speed of ship. Hirst: howr 205.2, 178 about 24 knots) 724,15 Second hour 181 about 24.3 knots J Third hour... 186 about 25.0 knots 25.05 Fourth hour.... 187 about 25.1 knots} Mean for watch 183 about 24.6 knots Regarding the observations from readings taken in the engine room on the official trials. generally, it may be stated 'that on the measured miles the revolutions were obtained: from elec- tric records in connection' with the pallograph: apparatus, "but. "on the lengthened trials they were taken from half-hourly readings of the engine room counters. The vacuum recorded is that of the vapor in the main 'ex- haust orifice forming the top of the condensers, and as measured by a siphon mercury gage, the readings of which throughout are corrected to cor- respond to a 30 in. barometer. The total quantity of feed water is ob- tained from hourly counter readings of the double strokes of the Weir's feed pumps, the average length of stroke and the slip or leakage of each pump being determined, both before and after the trials, by careful tests. The consumption of steam of the auxiliary machinery is obtained by not- ing the amount by which the temper- ature of the total feed water was raised in the feed heaters, and to the amount thus found must be added the steam used in turbo-generators, the ex- haust from which was led direct to the auxiliary condensers on the official trials. As before stated, in actual ser- vice these turbo-generators exhaust into the contact heaters, and thus raise the feed temperature to about 200 de- grees. These connections had to be slightly altered at the time of the trials, and unfortunately, therefore, advantage could not then be taken of this addi- tional source of economy. The torque horsepower was obtained by the Denny-Johnson apparatus, and the records show that, while a pro- pulsive efficiency of the whole installa- tion was obtained which accorded with the original estimate, the steam con- sumption of the turbines . themselves . was very satisfactory. It need hardly be pointed out- that those two, viz., propulsive efficiency and steam con- sumption per unit of power, form an excellent check on each other, for, whatever would unduly favor one, would Us at the expense of the other. z * "filed with ~ Sate of. combustion » of - 'coal. of 29. The Lusitania was floated out of dry dock at Liverpool on July 22, 1907, and was thereafter coaled by the Cunard company, the bunkers for the forward and after boiler rooms being South Wales coal, and those of the two middle: boiler rooms with Yorkshire coal. On her return to the Clyde, on the morning of July 27, a series of pro- gressive runs was made on the Skel- morlie measured mile, as recorded on Table I (at end of paper), with the ship at a mean draught of 32 ft. 9 in. These results are also given in graph- ical form in the diagram on Fig. 5, which gives curves of shaft horsepow- er, revolutions, and slip, on a common speed base. Two other most inter- esting curves have: been added, one-- showing the effective horsepower de--. termined by means of tank -experi-. ments, and the other showing the pro-. pulsive efficiency. It was intended -to ~ repeat 'this trial at the termination -of- the official trials. at a mean draught . of about 30 ft. Unfortunately; how- ever, thick weather on the morning of August 2 prevented this being carried out, but the dotted curve on Fig. 5 in- dicates with sufficient accuracy what might have been expected. On the evening of the 27th the Lusi- tania proceeded on a. pleasure cruise round Ireland, during which consump- tion trials at 18, 21 and 23 knots were carried out, and, after landing. the guests in the forenoon of the 29th, the vessel returned to the Clyde, mak- ing a consumption trial at 1534 knots enroute, the results of these trials be- ing given in the first four columns of Table V. After checking the draught of ship, etc., the 48 hours' full speed continuous trial was commenced at midnight. This trial consisted of two © double runs on a course of 304 knots ~ between Corsewall Point and the Longships, and the results obtained are recorded on Table II, and the | last columns of Table V. The mean_ draught at starting was 32 ft..7 in, and at the finish about 30 ft. 8 in. The coal consumed in the 50. hours during which the engines were running at full speed was found by meas-" urement of bunkers to be about 2,200 tons. This represents an evaporation of 10.1. -pounds of water per pound of coal from. 165. degrees temperature of -- feed, or ft pounds: from and at, 212 'degrees, and a consumption of 'coal! for all..purposes - of. 1.43 "Sounds | "per.|g shaft horsepower per hour, with a 24.3 pounds per square foot of grate sur-. face per hour. The number of stokers on watch was the same as in actual