September i6, 1909] 



NA TURE 



349 



1 1 knots, which would have required on the measured 

 mile only about 40 per cent, of the power developed when 

 running 14-6 knots. With the ship laden more deeply, 

 the average development of power on the voyage was 

 about one-half the maximum developed on the measured 

 mile, and this was disadvantageous to economy in the 

 combination. Even in these unfavourable conditions the 

 Oiaki realised an economy in coal consumption of 8 per 

 cent, on the voyage from Liverpool to New Zealand and 

 back as compared with her reciprocating-engined sister 

 ship ; this represents a saving of about 500 tons of coal. 

 Ordinarily the ship would leave England with sufficient 

 coal on board for the outward passage, so that 250 tons 

 less coal need be carried and a corresponding addition 

 could be made to cargo and freight-earning. Probably as 

 experience is gained the actual economy will prove greater 

 than that realised on the maiden voyage ; but even as 

 matters stand there is a substantial gain, and a prospect 

 of the extended application of the steam turbine to vessels 

 of moderate and low speed. In view of results already 

 obtained, the New Zealand Shipping Company have decided 

 to apply the combination system to another vessel just 

 ordered from Messrs. Denny. 



In designing turbine machinery for vessels of moderate 

 or low speed there must necessarily be conflicting claims. 

 For maximum efficiency in steam turbines a high rate of 

 revolution is necessarv, whereas at moderate or low speeds 

 it is antagonistic to propeller efficiency to run at this high 

 rate of revolution. Engineers are at present much occupied 

 with the study of arrangements by means of which these 

 conflicting claims mav be harmonised and greater total 

 efficiency of propulsion obtained. Having regard to the 

 enormous capital invested in cargo steamers of moderate 

 speed, and the importance attaching to their economic 

 working as influencing the cost of over-sea transport, it 

 will be obvious that it is most desirable to find an arrange- 

 ment in which the high speed of the rotor may be reduced 

 by means of some form of gearing or its equivalent, so 

 as to enable the screw shaft and its propeller to be run 

 at a speed which will secure maximum propeller efficiency. 

 Many proposals have been made, including mechanical 

 gearing and hydraulic or electric apparatus, for transform- 

 ing the rate of motion. Some of these are actually under- 

 going experimental trials, and are said to have given very 

 promising results. One of the most important trials is 

 that undertaken by the Parsons Marine Steam Turbine 

 Company, which has purchased a typical tramp steamer, 

 and is carrying out on her a series of trials in order first 

 to ascertain accurately what are the actual conditions of 

 steam and coal consumption with the present reciorocating 

 engines, and then to. ascertain the corresponding facts 

 when those engines have been removed and a steam turbine 

 with its associated gearing has been fitted. It is interest- 

 ing to note in passing that in the earliest davs of screw 

 propulsion with slow-running engines it was found neces- 

 sary to adoot gearing in order to increase thp rate of 

 revolution of the propellers, whereas at present interest is 

 centred in the converse operation. Furthermore, if any 

 system of gearing-down proves successful, it may be 

 anticipated that its application will be extended to swift 

 turbine-driven steamships, since it would enable i^ood pro- 

 pulsive efficiency to be secured in association with rapidly 

 running turbines of smaller size and less weight than have 

 been employed hitherto. 



The Marine Steam Turbine. 

 The rapid development of the marine steam turbine 

 during the last seven years constitutes one of the romances 

 of engineering, and the magnitude of the work done and 

 the revolution initiated by Mr. Charles Parsons will be 

 more justly appreciated hereafter than it can be at present. 

 In some quarters there is a tendency to deal critically with 

 details and to disregard broader views of the situation as 

 it stands to-day. In May, iqog, there were 273 vessels 

 built and under construction in which steam turbines of 

 (he Parsons type are employed, the total horse-power being 

 more than three and a half millions. In the Royal Navy 

 every new warship, from the torpedo-boat up to the largest 

 battleships and armoured cruisers, is fitted with turbine 

 engines ; and the performances of vessels which have been 

 tested on service have been completely satisfactory, in 



NO. 2081, VOL. 81] 



many instances surpassing all records for powers developed 

 and speeds attained. In the war-fleets of the world this 

 example is being imitated, although in some cases it was 

 at first criticised or condemned. In the mercantile marine 

 as a whole, while the new system has not made equal 

 advance, many notable examples can be found of what 

 can be accomplished by its adoption. It is now admitted 

 that steam turbines enable higher speeds to be attained 

 in vessels of given dimensions ; and in steamers built for 

 cross-channel and special services, where high speed is 

 essential and coal consumption relatively unimportant, 

 turbines have already ousted reciprocating engines. For 

 over-sea service and long voyages an impression has existed 

 that the coal consumption of turbine-engined ships would 

 considerably exceed that of ships driven by triple or quad- 

 ruple expansion reciprocating engines. Critics have dwelt 

 on the reticence in regard to actual rates of coal consump- 

 Tion practised by owners of turbine steamships. Naturally 

 there are other reasons for reticence than those which 

 would arise if the coal consumption were excessive ; but 

 pioneers in the use of turbine machinery may reasonably 

 claim the right of non-publication of results of trials in 

 the malving of which they have incurred large expenditure 

 and taken considerable risks if they think that silence is 

 beneficial to their business interests. Even if it were true 

 that in the earliest applications of the new system economic 

 results had not been obtained equal to those realised in 

 reciprocating engines which have been gradually improved 

 during half a century, that circumstance should not be 

 regarded as a bar to acceptance of a type of engine that 

 admittedly possesses very great advantages in other ways, 

 but should be regarded as an incentive to improvements 

 that would secure greater economy of coal. The evidence 

 available, hfiwever, does not confirm the adverse view, and 

 those familiar with the facts do not admit its truth. One 

 example may be cited as it affects the Canadian service. 

 In June, 1907, it was authoritatively stated that in the 

 Allan liner Virginian the reports which had been circu- 

 lated respecting the excessive coal consumption were un- 

 founded, that the vessel was making passages at speeds 

 of I7i to 17I knots, as against the 17 knots estimated, 

 and the rate of coal consumption was really about i.4_ lb. 

 per indicated horse-power which would have been required 

 to attain this speed if the vessel had been fitted with 

 reciprocating engines. This result compares well with the 

 consumption in ordinary passenger steamers running at 

 high speeds in proportion to their dimensions, although in 

 large cargo steamers and vessels of the intermediate type, 

 working under much easier conditions and at very low 

 speeds in proportion to dimensions, lower rates of con- 

 sumption may be obtained. With these latter vessels the 

 fair comparison is the combination system and not the 

 pure turbine type which is adapted for high speeds. 



The crowning triumph of the marine steam turbine up 

 to the present time is to be found in the great Cunard 

 steamships Lusitania and Matireiania. The passages made 

 this year by the latter ship since she was refitted have 

 been marvellously regular, and the 25 knots average across 

 the Atlantic, which was the maximum contemplated in the 

 agreement between the Government and the Cunard Com- 

 panv, has been continuously exceeded. As one intimately 

 concerned with the design of the Matirelania, who has 

 had large experience in ship design, has made a life-long 

 study of the laws of steamship performance, and had the 

 honour of serving on the committee which recommended 

 the employment of turbines in these great ships, the writer 

 ventures to assert that equal results could not possibly 

 have been obtained with reciprocating engines in vessels 

 of the same form and dimensions. Contrary opinions have 

 been expressed, but they have been either based upon in- 

 correct data or have omitted consideration of the fact that 

 in vessels of such great engine-power it was necessary to 

 have time to perfect the organisation of the staff in order 

 to secure uniform conditions of stoking and steam pro- 

 duction, and to bring the "human element" into acon- 

 dilion which would ensure the highest degree of efficiency 

 in working the propelling apparatus. This necessity for 

 time and training has been illustrated again and _again_ in 

 the case of new types of Transatlantic steamers, including 

 some which held the record for speed prior to the appear- 

 ance of the Cunarders. In the Lusitania and Mauretania 



