ON THE PROGRESS OF SCIENCE. IX 



Germany, exhibited a small steel cannon as the most notable achieve- 

 ment hitherto effected in this branch of metallurgy. Four years 

 subsequently, in 1855, M. Krupp sent to the Paris Exhibition a steel 

 ingot that weighed five and one-half tons ; while to the one held last 

 year in London he sent a crank axle that weighed no less than 

 twenty tons. 



Some extracts gleaned from a recent report by Mr. Fairbairn, the 

 eminent English engineer, on the steam " Machinery of the London 

 Exhibition of 1862," will also be found interesting in this connection. 

 Mr. Fairbairn states "that in 1859 the steam engines employed in 

 the various factories, steamships, and locomotives of Great Britain 

 amounted to 10,950,000 horse power, but that at the present time 

 this sum has increased to 12,000,000 horse power, and this maybe 

 taken as the steam motive force in the British Islands." 



Mr. Fairbairn further goes on to say, " that nearly all engines at 

 the present time work the steam expansively ; that is to say, they are 

 so arranged in the construction of the valve motions as to cut off the 

 communication with the boiler at one-third, one-half, or two-thirds of 

 the stroke, as the case may be, in regard to pressure, or the power to 

 overcome the resistance of the load. Some engineers go so far as to 

 cut off the steam at one-sixth and one-eighth, and expand the re- 

 maining five-sixths or seven-eighths of the stroke. Formerly the 

 principle of expansive working was very imperfectly developed ; but 

 that system is now thoroughly understood, and is in almost every case 

 resorted to. The result of its introduction has been an immense 

 economy ; for the quantity of work now done with the same quan- 

 tity of fuel is more than double what was formerly accomplished 

 on the old non-expansive principle. It must, however, be borne in 

 mind that this cannot be effected without an increase of the pressure 

 of steam, and hence follows the necessity of having the boilers of in- 

 creased strength and improved construction. The neglect of these 

 precautions has resulted in serious and fatal accidents, attended with 

 a considerable loss of life and property. Irrespective of increased 

 pressure, and working the steam expansively, the speed of the engine 

 has been increased about one-third since the days of Watt. In his 

 time the piston of the stationary engine travelled at the rate of two 

 hundred and forty feet per minute ; now it averages from 300 to 320 

 feet ; and this, combined with high-pressure steam worked expansively, 

 increases the power of the engine, in some cases, upwards of two-fold, 

 and, as already stated, doubles the quantity of work done with the 

 same quantity of fuel. Thus an important saving is effected to this 



