THE LOCOMOTIVE. 



26. Iji the progress of the English railways, locomotives have 

 been, from time to time,^ast aside, and put, as it were, upon the 

 retired list ; but this has often arisen, not from the circumstance 

 of their being superannuated, but because the conditions of the 

 traffic had undergone such a change that the natural powers of 

 these engines were not suited to it. Immediately after the com- 

 mencement of the operation of the railway system, the traffic aug- 

 mented so rapidly as to exceed all the previsions of those who 

 constructed and organised the first railways. The weight and 

 strength of the rails were successively increased, as well as the 

 weight and magnitude of the trains, and the weight and power of 

 tine engines underwent a corresponding augmentation* 



A regularly kept journal of the life of some of the oldest loco- 

 motives working on the English railways would be a record of 

 profound interest. Whether such a register exists, I am not 

 aware; but none such has, I believe, ever been published. 



27. From a comparison of the total mileage of each class of the 

 locomotive stock with the number of engines in service, the average 

 mileage of each engine can be ascertained. 



As an example of such a calculation, let us take the Belgian 

 railways for 1847. 



The total number of engines in active service was 154, and their 

 total mileage was 2,366885 ; this divided by 154 gives 15369 as 

 the average annual mileage of each engine, the average daily 

 mileage being therefore 42 miles. 



28. It may be asked, whether a locomotive engine, once lighted, 

 may not be worked almost indefinitely ? 



It is known that many steam-engines used in the manufactures 

 and in mining are kept for several months together in unceasing 

 action night and day ; and the engines used in steam-ships are 

 often kept in incessant operation throughout a voyage of 3000 

 miles. Why therefore, it may be demanded, may not a locomo- 

 tive engine be worked for a much longer distance without inter- 

 ruption, and thus distribute the expense of lighting and cleaning 

 over a greater extent of mileage, and thereby diminish the cost 

 per mile ? 



Although the mileage of the engine might be augmented much 

 beyond its present amount, it is nevertheless indispensable that it 

 should not exceed a certain practical limit. The locomotive engine, 

 an iron horse, requires intervals of repose as much as do the horses 

 of flesh, blood, and bones. It becomes fatigued, so to speak, with 

 its work, and its joints become relaxed by labour, its bolts loosened, 

 its rubbing surfaces heated, and often unequally expanded and 

 strained. Its grate-bars and fire-box become choked with clinkers, 

 its tubes become charged with coke; and were its labour continued 

 136 



