264 TRANSACTIONS OF SECTION G, 



and reference was made to the anti-tank devices used by the enemy. Reference 

 was also made to the tanks made by the French, and also to the few that were 

 made by the. Germans as a reply. 



There was a section referring to the tactics of tanks and general considera- 

 tions from a tactical and strategical point of view. 



The paper concluded with a reference- to the fact that the British engmeers 

 were able to introduce a new engine of war in advance of anything which the 

 enemy had been able to devise, and that in this advance British engineers 

 kept ahead to the end of the war, the importance of maintaining this position 

 being emphasised. 



2. Portable Military Bridges. By Professor C. E. Inglis.^ 



3 Development of Geared Turbines for the Propulsion of Ships. 



By E. J. Walker.^ 



Although the successful application of the steam turbine to marine propulsion 

 dates back to the year 1897, when Sir Charles Parsons demonstrated in that 

 now historical vessel, the Turbinia, the great advantages of the turbine system 

 when applied to the propulsion of ships, it is only within the last few years 

 that mechanical gearing has been largely adopted in association with steam 

 turbines. 



The author dealt with the application of the steam turbine when directly 

 connected to the propeller shaft both in war and mercantile vessels of high 

 and moderate speeds. 



The chief governing factors in marine steam turbine design are those of 

 economy, weight, and first cost, and it was found in actual practice that the 

 problem of applying the turbine direct to the propeller was satisfactorily solved 

 to fvlfil these conditions for vessels of about 18-knots speed and upwards. 



Up to the year 1909 the steam turbine had not been applied to vessels of 

 slow and intermediate speeds, with the exception, in a few instances, of the 

 combination of reciprocating engines with a low-pressure turbine. 



In view of the success obtained by Dr. De Laval, of Stockholm, with helical 

 gearing in connection with his turbine for land purposes for powers up to about 

 60O b.h.p., Sir Charles Parsons decided to test turbines mechanically geared 

 to the screw shaft in a typical cargo vessel, and in 1901 experiments were 

 carried out, the results of which fully demonstrated the suitability of mechanical 

 gearing for the propulsion of ships. 



Several forms of gearing have been proposed, such as electrical, hydraulic, 

 and mechanical. Electrical and hydraulic transmission gears have been fitted 

 in a few ships, but the greater majority have been fitted with mechanical 

 gearing. 



Although gearing was primarily introduced to widen the field of operation 

 of the turbine by its adoption for vessels of low speed, it was quickly recog- 

 nised that increased efficiency in fast vessels could be obtained by means of 

 reduction gearing. 



The author referred to the progress that has been made in the application 

 of mechanical gearing for both war and merchant ships, and the advantages 

 that have accrued by its adoption. Vessels have been put into commis- 

 sion with installations of geared turbines of 100,000 horse-power each, 

 the horse-power actually transmitted through a single gear being 25,000, and 

 the power through a single pinion reaching 15,500 shaft-horse-power. 



At the present time the total number of vessels with geared turbines for 

 war and commercial vessels built and under construction is 818, corresponding 

 to a total shaft-horse-power of sixteen millions. 



The increased efficiency that has been effected since the earlier days of the 

 ffieam turbine; the measures taken to produce quiet running gears; the advance 



- See Engineering, Sept. 26, 1919, p. 408. 

 3 gee Engineering, Sept. 19, 1919, p. 386. 



