134 SECTIONAL ADDRESSES. 



Shipbuilding is especially interesting inasmuch as it combines in one 

 structure the varied efforts of almost every class of artisan dealing with 

 both iron and steel and cabinet-making and woodworking generally, in 

 addition, of course, to the large and varied amount of mechanical 

 engineering. In marine engineering the last fifty years have, indeed, a 

 most interesting record of progress, and in very early years such firms as 

 Humphreys Tennant, Maudslay, Son & Field, and other firms no longer 

 in existence, introduced a measure of precision into mechanical engineering 

 probably not then existing in any other branch of the industry. High and 

 low pressure triple expansion engines held their own for a considerable 

 period, and it was, I suppose, the interesting trials of the Turhinia which 

 brought about the first change from this method. It is an interesting 

 fact that our fellow-member. Sir Charles Parsons, to whom I have already 

 alluded, should live to see such successful development of his patent, and 

 a recent paper read by him and his co-workers describes in a very 

 interesting manner the gradual developments and changes in design in 

 turbines up to the present time. Such developments range from the 

 Turhinia, which had a displacement of 44^ tons with 2,100 h.p., to the 

 battle cruiser Hood of 41,200 tons and over 150,000 h.p. 



The introduction of geared turbines, so as to arrive at relatively 

 efficient speed as between engine revolutions and propeller revolutions, 

 has brought about valuable economies and helped the turbine principle 

 to maintain its reputation. The development of internal combustion 

 engines for marine purposes has made great strides in recent years. 

 Various types of these engines are already in active service, and a horse- 

 power of 36,000 on four propellers has already been achieved with 

 efficiency ; probably the limit has not yet been reached. The use of oil 

 instead of coal on board ship, especially for passenger purposes, represents 

 many advantages, and anyone who has visited the stokehold of a large 

 passenger liner with the hundreds of men stoking with coal must realise 

 the immense advantage, both physical and otherwise, which results from 

 oil burning directly on the boilers. All inconvenience caused by dust in 

 re-coaling is avoided, and the boiler tenting is carried out by young 

 mechanical engineers, doing away with all the labour required by coal 

 burning. In a vessel of large tonnage the saving in wages and maintenance 

 of several hundreds of stokers represents an enormous economy in many 

 directions. The question of larger horse-power and/or electrically driven 

 ships is one of the problems which marine engineers are at present turning 

 their minds to. 



A new development which is now being introduced is the use of con- 

 siderably higher steam pressures in boilers. The first application of this 

 was the King George V., a boat built last year on the Clyde, and our section 

 has been favoured with a paper from Mr. Harold Yarrow dealing with 

 some of the problems which have arisen in introducing high pressures. 

 As you will have gathered from his paper, these problems are not solely 

 those of the engineer who has to build the boilers. They are closely 

 associated with steel and metallurgical questions incident to the special 

 manufacture of parts of the boilers owing to the much greater strength 

 required. Many of my audience, no doubt, have been interested in the 

 valuable information we have received from the paper in question. 



