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June, 1909 out of the question to apply the tur- bines to the propeller shafting without the use of some form of intermediate gearing. In the first place, in order to have the revolutions per minute such that the weight of machinery would re- main unaltered, it woutd be necessary to adopt propellers with a pitch ra- tio of about 0.55. Now,. the pitch ratio of most turbine-driven propel- lers is in the neighborhood of unity, and although they work behind fine lined ships, their efficiency is decided- ly low. What, then, can be expected from propellers with a pitch ratio of 0.55 working behind the bluff stern of a cargo tramp with a 20 per cent wake? Something might be done by the adoption of some form of gear- ing, but the problem is capable of no easy solution. It is rather difficult to understand this anxiety to discard the well-tried piston engine for the steam turbine in this class of vessel, for the advantages to be gained by so doing are not at all evident. The reciprocating engines. fitted to the or- dinary cargo tramp are very econom- ical in themselves, and are combined with the propellers which are best suited to this class of work. They are thoroughly understood and _ re- quire and generally receive very lit- tle attention when under way. On the other hand, it is impossible to ob- tain a reasonable efficiency from the fine pitch ratio screws associated with the turbine system when work- ink behind such vessels, to name only one difficulty. : Propeller the Weak Point. From the whole of the foregoing remarks and comparisons it is ob- vious that the propeller is the weak point in the turbine system, and that with the efficiencies obtained up to the present the turbine can only com- pete successfully with the least effi- cient classes of reciprocating marine engines. No doubt some :mprovement in this direction may be expected as a more accurate knowledge of the performance of turbine-driven pro- pellers is obtained. An important step in this direction would be the adoption of a practical form of thrust meter, and the direct measurement of thrust horsepower. However, at the best the improve- ment to be expected cannot be of great amount. Thus it would ap- pear that the extent of the success- ful application of the marine steam turbine in» its present form to mer- chant vessels is likely to remain con- Siderably restricted --The Engineer. TAE Marine REVIEW 137 scout Cruiser Trials The navy department recently gave out a preliminary report 'covering the coal consumption ttests of the scout cruisers Salem, Birmingham and Chester. The results tabulated are as follows: Test No. 1. Duration of Trial, 96 Hours. 10 Knots Speed. Birmingham. 'Chester. Salem. Feed water used per day 10.55 10.97 11.66 Coal used, tons per day 31.74 40.44 53.85 Test No. 2. - Duration 'of 'Trial, 50 Hours. 15 Knots Speed. Feed water used perday 13.9 13.2 12.12 Coal used, tons per day 71.23 85.62 107.23 Test No. 3. Duration of Test, 98 Hours. 20 Knots Speed. Feed water used per day 26.1 16.8 1751 Coal used, tons per day 153.47 157.15 202.03 Test No. 4. Duration of Test, 24 Hours. Maximum Speed. (Due to an accident the Birmingham discon- tinued this test after 12 hours.) Feed water used per day 120.4 27.0. 45.625 'Coal used, tons per day 375.72 416.7 415.7 Owing to the damage to the star- board turbine of the Salem, which was not known at the time of the test, the navy department does not consider the tests, as regards the Salem, ac- curate or conclusive, and they will be repeated. No definite announcement has been made as to the nature of the accident to the Birmingham which occurred on her 24-hour maximum speed test. In the case of the Salem it was noted that the starboard turbine ran consid- erable slower than the port with the same steam supplied. When opened up it was discovered that some foreign body nad become caught in the fifth stage between the nozzles and first row of buckets. It had bent over the edges of the buck- ets so as to completely prevent any steam passing through them and had broken about one-quarter of the noz- zle division plates. The foreign body . which caused this has not yet been found, but a loose %-in. nut was found in the fifth. stage lying in the bottom of the casing and did not be- come caught in the moving parts. Examination of the port turbine dis- closed a service bolt 214 in. long, which was not a part of the machine, lying in the first stage against the nozzle openings leading to the sec- ond stage. The damage done here was comparatively slight. The rotors of both machines were also found to have. moved axially so as to allow the moving buckets to rub against the _ stationary guide blades, with the result that in the first- and second stages where the axial clearances are least, the guide blades were worn on the edges; but no blade stripping occurred. As in these stages the guide blades only 'cover a small part of the circumfer- ence, practically all the wear occurred on them and very little on the moy- ing buckets. All blading was found to be entirely free from any erosion due to the ac- tion of the steam, and the surfaces were. as smooth as when first in- stalled. The Fore River Ship Building Co. makes no charge of vandalism regard- ing the damage, believing that the bolts may have been accidentally DAMAGED BUCKETS OF THE CRUISER SALEM,