STEAM TURBINES AND HIGH-SPEED VESSELS. 70s 



thirty-knot destroyers now in her Majesty's service, but have 

 slightly more displacement. The boilers are about twelve per 

 cent larger, and it is estimated that upward of ten thousand horse 

 power will be realized under the usual conditions, as against sixty- 

 five hundred with reciprocating engines. 



The engines of these vessels are in duplicate. Two screw shafts 

 are placed on each side of the vessel, driven respectively by a high- 

 and a low-pressure turbine; to each of the low-pressure turbine 

 shafts a small reversing turbine is permanently coupled for going 

 astern, the estimated speed astern being fifteen knots and a half, 

 and ahead thirty-five knots; two propellers are placed on each 

 shaft.* 



The latter of these two vessels has commenced her preliminary 

 trials, and has already reached a speed of thirty-two knots. The 

 manipulation of the engines is a comparatively simple matter, as 

 to reverse it is only necessary to close one valve and open another, 

 and, owing to there being no dead centers, small graduations of 

 speed can be easily made. 



In regard to the general application of turbine machinery to 

 large ships, the conditions appear to be more favorable in the case 

 of the faster class of vessels such as cross-Channel boats, faster 

 passenger vessels, cruisers, and liners; in such vessels the reduction 

 in weight of machinery, as w'ell as economy in the consumption of 

 coal per horse power, are important factors in the case, and in some 

 vessels the absence of vibration, both as regards the comfort of 

 passengers, and in the case of ships of war permitting greater accu- 

 racy in sighting of the guns, is a question of first importance. 



As regards cross-Channel boats, the turbine system presents ad- 

 vantages in speed, absence of vibration, and, owing to the smaller 

 diameter of the propellers, reduced draught. 



As an instance, a boat of two hundred and seventy feet length, 

 thirty-three feet beam, one thousand tons displacement, and eight 

 feet six inches draught of water could be constructed with spacious 

 accommodation for six hundred passengers, and wdth machinery de- 

 veloping eighteen thousand horse power; she will have a sea speed 

 of about thirty knots, as compared with the speed of nineteen to 

 twenty-two knots of the present vessels of similar size and accom- 

 modation. 



It is, perhaps, interesting to examine the possibilities of speed 

 that might be attained in a special unarmored cruiser, a magnified 

 torpedo-boat destroyer of light build, w'ith scanty accommo(hition 



* On her second trial trip the Viper attainsd a mean speed of 34.8 knots, her fastest 

 trial being over 35 knot?, or about 41 statute miles per hour, with an indicated horse power 

 of 11,000. This vessel is of about 350 tons displacement. 

 VOL. LVI. — 5fi 



