.28 



NA TURE 



[March i, 1900 



contracted with the Admiralty for a 31 -knot torpedo-boat 

 destroyer, the Viper (Fig. 2), which is of the same dimensions 

 as the usual 30-knot vessels of this class, viz. 210 feet length, 

 21 feet beam, and about 350 tons displacement, but with 

 machinery of much greater power than usual in vessels of this 

 size ; they also contracted with SirW. G. Armstrong, Whitworth 

 and Co. for machinery for one of their torpedo boat destroyers. 



The turbine engines of these vessels are similar to those of the 

 Turblna, but are in duplicate, and consist of two distinct sets of 

 engines on each side of the vessel. There are four screw shafts 

 in all, entirely independent of each other, the two on each side 

 being driven by one high and one low-pressure turbine respec- 

 tively of about equal power ; the two low-pressure turbines drive 

 the two inner shafts, and to each a small reversing turbine is also 

 permanently coupled, and revolves idly with them when going 

 ahead. The screw shafts are carried by brackets as usual, and 

 two propellers are placed on each shaft, the foremost in each 

 case having a slightly lesser pitch than the after one. The 

 thrust from the screw shafts is entirely balanced by the steam 

 acting on the turbines, so that there is extremely little friction. 



The boilers, auxiliary machinery and condensers are of the 

 usual type in such vessels, but their size is somewhat increased 

 to meet the much larger horse-power to be developed, and to 

 compensate for the lesser weight of the main engines, shafting, 

 propelleis, as well as the lighter structure of the engine beds. 

 The boilers are of the Yarrow type, with a total heating surface 

 of 15,000 square feet, and grate surface of 272 square feet, and 

 the condensers have a cooling surface of 8000 square feet. The 

 hull and all fittings are of the usual design. 



Let us consider the machinery on one side of the vessel only : 

 the steam from the boilers is admitted directly through a regu- 

 lating valve to the high-pressure turbine driving one shaft, it then 

 passes to the adjacent low-pressure turbine, diiving its shaft in- 

 dependently, thence it flows to the condenser, and both the 

 shafts then drive the vessel ahead ; the reversing turbine revolves 

 with the low-pressure .shaft, and being permanently connected 

 with the vacuum of the condenser no appreciable resistance is 

 offered to its motion under these conditions. To go astern the 

 ahead steam valve is closed and the astern steam valve opened, 

 admitting the steam from the boilers to the reversing turbine, 

 and reversing the direction of rotation of the inner screw shaft. 



On the other side of the vessel the arrangement is the same, 

 and it will be seen that she can be manoeuvred as an ordinary 

 twin-screw vessel, and with great facility and quickness. 



On her second preliminary trial about three weeks ago, the 

 mean speed of four consecutive runs on the measured mile reached 

 34'8 knots, and the fastest run was at the speed of 35 '503 knots, 

 which is believed to be considerably beyond the recorded speed 

 of any vessel hitherto built. The vessel was scarcely completed 

 at the time of this trial, and it is anticipated that still higher 

 speeds will be realised on subsequent and official trials. The 

 speed of 35 '5 knots, or nearly 41 statute miles, represents about 

 11,000 indicated horse-power in a vessel of 350 tons displace- 

 ment, as compared with 6000 to 6500 developed in the 30-knot 

 destroyers of similar dimensions and 310 tons displacement. 



At all speeds there was very little vibration. Her speed 

 astern is guaranteed to be 15I knots. 



The Viper has surpassed the Turbinia in speed, and is at the 

 present time the fastest vessel afloat. 



In regard to the general application of turbine machinery to 

 large ships, the conditions appear to be more favourable in 

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

 passenger vessels, liners, cruisers and battleships ; in all such 

 vessels the reduction in weight of machinery, and economy in 

 the consumption of coal per horse-power, are important 

 factors ; in some the absence of vibration is a question of first 

 importance, as affecting the comfort of passengers, and, in the 

 case of ships of war, permitting of greater accuracy in sighting 

 of the guns. 



The model exhibited represents a proix)sed cross-Channel 

 baat for the Dover and Calais or Newhaven and Dieppe routes. 

 She is 270 feet length, 33 feet beam, 1000 tons displacement, 

 and 8 feet 6 inches draught of water. She has spacious accom- 

 modation for 600 passengers, and with machinery developing 

 18,000 horse-power would have a sea speed of about 30 knots 

 as compared with the speed of 19 to 22 knots of the present 

 vessels of similar size and accommodation. 



It is perhaps interesting to examine the possibilities of speed 

 that hiight be attained in a special unarmoured cruiser, a mag- 

 nified torpedo-boat destroyer of light build, with scanty accom- 



modation for her large crew, but equipped wiih an armament 

 of light guns and torpedoes. Let us assume that her dimen- 

 sions are about double those of the 30-knot destroyers, or of 

 the Viper, with plates of double the thickness, and specially 

 strengthened to correspond with the increased size and speed, 

 length 420 feet, beam 42 feet, maximum draught 14 feet, dis- 

 placement 2800 tons, indicated horse-power 80,000, there 

 would be two tiers of water-tube express boilers, these, the 

 engines and coal bunkers, would occupy the whole of the 

 lower portion of the vessel, the crew's quarters and armaments 

 would be on the upper decks. There would be eight pro- 

 pellers of 9 feet in diameter, revolving at about 400 revolutions 

 per minute, and her speed would be 44 knots. She could 

 carry coal at this speed for about eight hours, and she would be 

 able to steam at from 10 to 14 knots, with a small section of 

 the boilers and supplemental machinery, more economically 

 than other vessels of similar size, and of ordinary type and 

 power, and when required all the boilers could be used, and 

 full power exerted in about half an hour. 



In the case of an Atlantic liner or a cruiser of large size, 

 turbine engines would effect a reduction in weight of ma- 

 chinery, and also increased economy in fuel, tending either to a 

 saving in coal on the one hand, or, if preferred, to some 

 increase in speed on the same coal consumption per voyage. 



In conclusion, it may be remarked that in the history of en- 

 gineering progress, the laws of natural selection generally 

 operate in favour of those methods which are characterised by 

 the greater simplicity and greater economy, whether these ad- 

 vantages be great or small. 



The work in this undertaking has perhaps been slow, but 

 many difficulties were met with besides those of a mechanical 

 nature, and, as is generally the case, the success so far attained 

 has been largely due to devoted colleagues and staff, and in the 

 marine developments to the enterprising and generous financial 

 assistance. 



My thanks are due to the officials of this Institution for the 

 kind assistance they have afforded me in the arrangement of 

 the apparatus. 



NO, 1583, VOL. 61] 



ADVANCEMENT OF ELECTRICAL 

 CHEMISTRY. 

 C\^ reviewing the science of electro-chemistry and its appli- 

 ^■'^ cation to modern manufacturing processes, one is struck 

 with amazement at the enormous strides which have been made 

 within the last ten or twenty years. On studying works on 

 chemistry little more than ten years old, hardly a reference is 

 found to the use of electricity in metallurgy, still less in regard 

 to the manufacture of metallic salts, or of the non-metals, 

 and absolutely none in reference to the preparation of organic 

 chemical bodies, at any rate on a large scale. 



We are told that in 1808 Sir Humphrey Davy discovered the 

 metals — sodium and potassium— by the electrolysis of their moist 

 hydroxides ; we are then informed that they are now manufactured 

 by the much cheaper method of heating the carbonates with 

 charcoal and chalk, or the hydroxides with carbide of iron. To- 

 day we find a retrograde step has been taken, and that they are 

 manufactured by the vastly cheaper method of electrolysing their 

 chlorides or hydroxides. 



Notwithstanding that Faraday aikl others early in the nine- 

 teenth century had shown that metals could be deposited, from 

 the solutions of their salts, upon other metals by means of an 

 electric current, and Faraday hlid, in 1833, formulated his law 

 that "The amount of any substance liberated is proportional to 

 the total quantity of electricity passed through the solution," '^ 

 and that "the amount of different substances liberated by the ' 

 same quantity of electricity are in the ratio of their chemical 

 equivalents"; electricity until quite recently was not used as 

 an adjunct to chemical analysis. Within the last few years 

 electro-chemical analysis has been very much studied, and now 

 most laboratories abroad are fitted with special apparatus for this 

 class of analysis. It is to be feared that in this country we are 

 hardly so advanced. 



Within the last thirty years the process for depositing metals, 

 from their solutions, and so obtaining moulds for casting, &c., 

 has not undergone any very radical changes, but the means at 

 our disposal for carrying out the work have enormously im- 

 proved. 



