March 24, 19 10] 



NATURE 



II I 



the coking of the fuel has not entirely removed the nitrogen 

 which was present in the coal. It also seems that, when 

 nitrogen has once entered pig-iron in the blast-furnace, it 

 cannot be removed by subsequent heating. It seems 

 desirable to ascertain more definitely by further experiments 

 how titanium acts in practice in the removal of nitrogen 

 from steel. 



A very important paper was presented by the Hon. C. A. 

 Parsons on the application of the marine steam turbine 

 and mechanical gearing to merchant ships. The steam 

 turbine has not hitherto been applied to vessels of slow 

 normal speed on account of the high initial cost and inferior 

 economy in steam. No promising scheme has, as yet, 

 been evolved whereby the efficient speed of the turbine may 

 be reduced and that of the propeller increased for vessels 

 of 12 knots sea speed and under. The only approach of 

 meeting these conditions has been in the combination 

 system of reciprocating engines and turbines, in which the 

 lower stages of the expansion are effected in the turbines. 



Provided the losses in transmission, first cost, and cost 

 of maintenance are not too great, the most satisfactory 

 solution for slow-speed vessels would appear to be by 

 means of gearing. Mechanical, electrical, and hydraulic 

 gearing have been proposed or applied, and the author 

 proceeded to give an account of his successful experiments 

 in developing a mechanical gearing. 



Helical and double helical gear wheels of fine pitch were 

 probably first introduced by De Laval in connection with 

 his turbine, and have proved to be very satisfactory and 

 efficient. Mr. Parsons has had several sets made. One 

 of these, made in 1897, gearing from 9600 revolutions of 

 the turbine to 4800 of the dynamo, transmitted 300 horse- 

 power with an efficiency of more than 98 per cent. This 

 gear ran fourteen hours a day for about a year. Recent 

 and better cut gears have given a total loss in the gear- 

 case of 15 per cent., including friction of gear and bear- 

 ings. 



The author was thus led to experiment with a view to 

 obtain comparative figures for a cargo vessel, first fitted 

 with ordinary reciprocating engines, and then with turbines 

 and mechanical gearing of the above-mentioned type. The 

 \ espasian was purchased for this purpose. Her dimensions 

 are : — length on load water-line, 275 feet ; breadth 

 moulded, 38 feet 9 inches; depth moulded, 21 feet 2 inches; 

 mean loaded draught, 19 feet 8 inches ; displacement, 4350 

 tons. The vessel was first fitted with triple-expansion 

 surface-condensing engines of ordinary pattern, cylinders 

 225 inches by 35 inches by 59 inches, and 42-inch stroke. 

 There were two boilers, each 13 feet in diameter and 

 10 feet 6 inches long, of total heating surface 3430 square 

 feet, and grate area of 98 square feet. The working 

 pressure was 150 lb. per square inch. A four-bladed cast- 

 iron propeller was fitted, having a diameter of 14 feet, 

 pitch 16-35 ^^et, and expanded area of 70 square feet. 



Before proceeding on the experimental voyage from the 

 Tyne to Malta, the reciprocating propelling machinery was 

 completely dismantled and overhauled. The machinery was 

 thus brought into an efficient and first-class working order. 

 Suitable tanks were provided for measuring the steam con- 

 sumption. Loaded with a cargo of coal, the Vespasian 

 left the Tyne on June 26, 1909, and careful measurements 

 of coal and water consumption were made throughout the 

 voyage by a special recording staff. 



On the completion of this voyage the vessel returned to 

 the turbine works, the reciprocating engines were removed, 

 and turbines and gearing fitted. The importance of these 

 trials lies in the fact that the only alteration made in the 

 vessel was in the type of propelling engines. Boilers, pro- 

 peller, shafting, and thrust blocks remained the same as 

 for the reciprocating engine. 



The turbine machinery consisted of two turbines in 

 series, one high-pressure and one low-pressure, the high- 

 pressure turbine being on the starboard side of the vessel 

 and the low-pressure on the port side. At the after end of 

 each turbine a driving pinion is connected, having a 

 flexible coupling between the pinion shaft and the turbine, 

 the pinion on each side of the vessel being geared into a 

 wheel which is coupled to the propeller shaft. A reversing 

 turbine is incorporated in the exhaust casing of the low- 

 pressure turbine. The usual air, circulating, feed, and 

 bilge pumps are driven from the forward end of the gear- 

 wheel shaft. The turbine and pinion shaft bearings are 



NO. 2108, VOL. 83] 



under forced lubrication ; the teeth of the gear wheels are 

 lubricated by means of a spray pipe extending over the 

 whole width of the wheel face. 



The high-pressure turbine is 3 feet maximum diameter 

 by 13 feet over-all length, and the low-pressure 3 feet 

 10 inches in diameter by 12 feet 6 inches in length. The 

 turbines were balanced for steam thrust only, the propeller 

 thrust being taken up by a thrust block. A new condenser 

 with a vacuum augmentor was fitted. The gear wheel is 

 cast iron with two forged steel rims shrunk on. This 

 wheel is 8 feet 33 inches in diameter of pitch circle, and 

 has 398 double helical teeth of circular pitch 07854 inch. 

 The total width of face of wheel is 24 inches ; the teeth 

 have an inclination of 20° to the axis. The pinion shafts 

 are of chrome nickel steel, 5 inches diameter of pitch 

 circle, with twenty teeth of 07854 circular pitch. The 

 ratio of the gear is 19-9 to i. 



On completion of the alterations, at the end of February 

 of this year, the vessel was loaded to the same draught 

 and displacement as that recorded for progressive trials on- 

 the Hartley mile with reciprocating engines. In the short 

 interval since the completion of the alterations the vessel 

 has been out to sea on four occasions. 



Mr. Parsons gives full information and curves showing 

 the results of the trials. We abstract the following 

 important figures from these. 



Water Consumption per Hour, for all Purposes- 



Lbs. of water per hour 

 Revolutions Spetd of 



of propeller vessel, knjts Reciprocating 

 engine-; 

 60 ... 8-87 ... 11,750 

 65 ... 9-55 ... 14,500 .. 

 70 ... IO*2 ... 17,500 .- 



Turbines 



10,750 

 12,600 

 14.750 



Savingv 

 per cent.- 



8-5 

 16 



The turbines and gearing have given no trouble, and 

 have worked satisfactorily, with very little noise or vibra- 

 tion, throughout the trials. There is no appreciable wear 

 on the teeth or bearings. It is proposed to put the vessel 

 into commission and run extended trials. Mr. Parsons 

 further added that the saving in weight on installing the 

 turbines amounted to 25 per cent. 



Speakers in the discussion were unanimous in com- 

 mending Mr. Parsons for his success, which is likely to- 

 revolutionise the means of propulsion of tramp steamers, ^ 

 which, as Sir William White remarked, form the back-' 

 bone of mercantile business. Prof. Ewing pointed out the 

 greater simplicity of mechanical gear as compared with 

 electrical, and also directed attention to its much higher 

 efficiency. He thought it most appropriate that the solu- 

 tion of this important problem should have fallen to the 

 lot of the inventor of the steam turbine. The economy of 

 Mr. Parsons 's new system could be simply expressed as 

 the saving of one boiler in six required for ordinary 

 reciprocating engines. 



AN INSTRUCTIVE EARTH MODEL. 

 A T the Hotel Cecil on March 17 Mr. G. R. Gill showed 

 ■^ a large model of the earth which, while large enough 

 to admit of the representation of surface features in detail, 

 can be packed into a comparatively small cabinet. A 

 rectangular box 5 feet by 3 feet by I5 feet is wheeled easily 

 into position, the folding lid is opened, a quadripod arrange- 

 ment is raised and made rigid, a steel axis with aluminium 

 ends is slipped into position, eighteen meridians are fitted 

 into the ends and stay in place by their own elasticity, 

 the three parts which go to form the equator are placed 

 by the side of the box, and this gives the arrangement of 

 the skeleton globe which is shown in Fig. i. 



The slope of the axis is adjustable to any angle, that 

 of 23^" being noted by a bell signal. The globe can be 

 made to rotate by hand or by electric motor. The diameter 

 of the globe is 4 feet 2^ inches, which gives a scale of 

 i/io*. The meridians are made of twelve thicknesses of 

 ven.' thin wood cemented and ri vetted together. 



The equator is then fixed, and from a cupboard thirty- 

 six sections are taken and fitted into place. Fig. 2 shows 

 the operation of inserting the last section, and shows, 

 approximately, the height of the erected globe. The 

 sections are of mild steel faced with papier-mdchi, and are- 



