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34 No 2k 1 NUE Rok Vy re Ww peller surface must be reduced, and this was done for the third series of trials. A point of interest is that the addition of a screw revolving in the neighborhood of the hull gave rise to considerable vi- bration, whereas in the first trials the complete absence of vibration was specially noteworthy. Third Trials--A third set of trials was made.on March 4, 1904, with propellers all of the same pitch (2 ft. 6 in.) and rather smaller diameter (2 ft. 6 in., 2 ft. 4 in., 2 ft. I in.). The speeds obtained were approximately equal to those of the second trials, for the same steam pressures in the H. P. tur- bine, but the speeds of rotation of the turbines were increased by 16 per cent. The increase in the efficiency of the engines was therefore balanced by the reduction in the efficiency of the screws, the slip of which rose to 24.6 per cent for those of the H. P. turbine, and 33.1 per cent for those of the L. P. Number of trial. i Il. Il. Iv. Effective pressure of steam on admission to H.P. turbine--lbs. per sq. in ........ 50 100 150 170 Condenser vacuum--inches............... 28 27.5 at : 27 Speed of vessel (two runs) knots ...... ; pon a - ae lee Mean speed of vessel--knots............ (. | 17.79 | 21.89 | 24.94 | 26.39 Rotation of reciprocating engine--Revs. PeromMINnUte< 2) oe 6 ene 458 508 555 576 Rotation of H.P. turbine -- Revs. per MING 2 a ee ees 836 1,052 1,207 1,258 Rotation of LP. turbine ---- Revs. per MINUte Oss Oe 836 1,065 | 1,282 | 1,307 Slip of propellers: Reciprocating engine--per cent........ 28.7 22.4 17 15.3 H.P. turbine--per cent.............--.-. 13 6 17.4 16.4 14.8 L.P. turbine--per cent .... ............ | 24.0 28.2 27.8 27.8 turbine. It seems to be difficult to obtain more than this with propellers grouped in pairs on each shaft. This arrangement of two propellers, one in front of the other is defective in so far that the second propeller works in water already disturbed by the first propeller. The highest efficiency is certainly ob- tained with a single propeller on each shaft, but in order that the slip should not exceed 25 per cent, which seems to be the maximum for a good duty, the propelling surface, and conse- quently the diameter, must be increased. This can be easily done when the shafts are nearly horizontal. On Messrs. Yar- row's boat, the inclination of the shafts is rather steeper than it should be with propellers having a diameter greater than the pitch. Nevertheless, the speed of 26.4 knots, which has al- ready been obtained, is no doubt capable of being improved upon, and the maximum obtained with reciprocating engines can no doubt be easily reached. In conclusion, it will be seen from what has been said, that steam turbines can be made practigally equal to reciprocating engines for propelling ships at high speeds, but in order to ob- tain their full effect, they must be mounted upon shafts very slightly inclined, and, if possible, with only one propeller on each shaft. The necessity for having horizontal shafts leads to a more sudden rise in the hull aft than is usual when recip- rocating engines are installed. Hence, hulls constructed for reciprocating engines are not generally suitable. for steam turbines. It must not be concluded from the fact that, ceteris paribus, a higher speed is not obtained by merely substituting turbines for reciprocating engines, that the former are there- fore inferior to the latter. A new form of propelling engine obviously calls for new lines of hull. At reduced speeds, the turbines are not economical, and they are inconvenient for go- ing astern and for maneuvering, but this drawback can quite well be remedied by combining turbines with a reciprocating engine working a special shaft and mechanically independent of the turbines. Another arrangement, different from that in the Yarrow boat, whereby the reciprocating engine would sup- ply about 40 per cent of the total power, would give an in- crease of 15 to 20 per cent of the power obtained with a recip- rocating engine alone, besides having the general advantages characteristic of turbines. SUMMARY OF NAVAL CONSTRUCTION. The commandant of the New York navy yard advises the Review that the Connecticut will be launched on Sept. 2g. She is given in the naval summary of construction as 44 per cent completed as against 50 per cent for her sister, ' building at the yard of the Newport News Ship Building & Dry Dock Co., Newport News, Va. Following is the summary: Degree of comple- tion. per cent. Battleships. Junel,'04. July 1,04. Ohio 2... .cn27-o.s. Union. Irom Works. 94.5 96 Nateinia ister oe Newport News Co. 61.2 62.4 Nebraska 0.03. Moran Brothers Co. 49 51 Georgia. «i065 4 Bath Iron Works. 54.13 2: 56.42 New Jersey ...... Fore River S. & E. Co. 58.7 61.8 Rhode Island .....Fore River S..& E. Co. 60.7 = 641 Connecticut ......Navy Yard, New York, N.Y. 42.1 . 44.82 Lousiana. sn... . Newport. News Co. . 49:31 50.76 Vermont .........Fore River S. & E.'Co. 8.9: 10:0. Kansas «..-......-New York'S. B. Co, 9.6 132° Minnesota sae oe Newport News: Co. =: 20.50" 34:27 Mississippi 2... .: Wim. Cramp & Sons. . a5 4.61 Idaho a Wm. Cramp & Sons. 32 4.68 Armored Cruisers. ee : : Pennsylvania ...-Wm. Cramp & Sons. 80.5 $2.7 West. Virginia....Newport News Co. 83.49 87.58 Caltfornia.'< 22. 6.2 Union Iron Works. 0035. 67 OL Colorada; +5. c.2-u, Wm. Cramp & Sons. * 300", 84:0... 864 Maryland . ....Newport News Co. -- 82.8 « » 85.07 South Dakota. eo. Union. Tron, Works: + ne S 58 Tennessee: s.¢2..2.Wmi Cramp :& Sons... ; oh BAe 385 Washington ...... 'New York .S, Br Co, oo 20es 34.4 eae - Protected Cruisers. Chattanooga .....Lewis Nixon. oo 7? 84.23. 88.04 Galveston' .......Wm. R. Trigg Co. ae Sr 84 Bt Ome... ene @ hevyCe, ee ga 43 Milwaukee ....Union Iron Works. 50.5 53 Charleston 2. Newport News Co. as 73 76:3 Gunboats. Dubuque os... ..Gas Engine & Power Co. 42.6 47:7 Paducah .........Gas Engines& Power Co... 35.7.» 38:7 ' * Training Ships: Cumberland -......Navy -Yard, Boston. 42 49° Intrepid: ..........Navy Yard,*Mare Island. 23.3 33:8 See ose : Training Brig. Boxer. ...,..+.,..Navy. Yard, Portsmouth. 42 55 Torpedo Boats. Siriano... Harlan & Holl'swth Co. 06 98 Goldsborough .... Wolff & Zwicker. 99 99 Blakely? i... 2s: Geo. Lawley & Son. 99 - QQ Nicholson 2.055. ; Lewis Nixon. 99 99 O'Brien .- Lewis Nixon. 98 98 The National Association of Engine & Boat Manufacturers has been definitely organized and the executive committee will meet on July 15 to elect officers. The executive commit- tee has been selected as follows: For one year, J. B. Smalley, C. L. Alpemus, C. L. Snyder, E. A. Riotte, A. Massanet; for two years, S. J. Matthews, A. Snyder, H. B. Brautigan, A. E. Eldredge, H. R. Sutphen; for three years, John J. Amory, H. A. Lozier; Jr, J. S. Bunting, H. N. Whittelsey, J. N. Schoon- maker. It is probable that the annual meeting will be held in October. The association is organized for mutual benefit. One of the subjects discussed at the meeting was the question of freight rates. It is found that the freight rate to South America was greater than the total cost of the boat, which was regarded as unreasonable. It was also discovered that there 1s no uniformity whatever in the matter of freight rates.