Recent Advances in Mechanical Science. 



\^\ 



converting it into power, we can only obtain a very small per 

 centage usefully (only from ten to twelve per cent). A little 

 anecdote, to illustrate the value of coal, may not be out of place 

 here. Some of those present mav have heard it, but it will 

 bear repetition for the sake of those who have not done so. — I 

 was travelling down some time ago from Dublin to Belfast in a 

 compartment of the train occupied by four gentlemen, evidently 

 from their conversation connected with, and interested in, 

 railway work. Among other subjects, they were comparing 

 the relative cost of fuel on several lines of railway, and they 

 made out that in an ordinary freight train a ton of cargo was 

 carried for twenty-five miles at a speed of fifteen miles an hour 

 for one pennyworth of coal. T happened to have the data of 

 carrying power, coal consumption, and speed of some large 

 cargo vessels, and I worked out the corresponding facts for the 

 results which had been obtained afloat. 1 was somewhat 

 astonished with the figures obtained, but they were quite 

 correct. It was simply a new way of looking at it, and it gave 

 me a respect for coal which I had not before possessed, and 

 which it would be well if this nation would realise before it 

 allows our coal fields to be emptied into foreign countries with 

 no national gain to us, very little gain for the coal proprietors, 

 and only benefiting the colliers, who consume the best part of 

 their earnings in intoxicating liquors. 



Taking such a vessel, I found her results to be : — average 

 sea speed, 15 miles ; coal carried, 6,500 tons; consumption, 51 

 tons per 24 hours. This works out (at 13/- per ton for coal, 

 which is about the cost of coal when put on board ship in, say 

 Liverpool) that one ton of cargo is conveyed no less than 294 

 miles for one penny worth of coal. 



Ship. 



D.W. 



in tons. 



Coal 



per day. 



Speed. 



Miles. 



One ton of cargo carried for id. 



Coalati2/-perton, 



At 13/- per ton. 



Imaum, 



Gaekwar, . . . 



Alex. Elder, 



X,... 



6420 



6575 

 6510 

 6500 



36 tons 

 27 » 

 33 » 

 51 » 



Knots. 



II 

 13 



per hour. 

 13-24 



I2-0 

 12-6 



15 



Miles. 



391 

 486 

 410 

 318 



Miles. 

 365 

 448 

 378 

 294 



