434 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



sino-ly or in pairs, by hollow cylindrical bars pierced with 

 holes, and so arranged as to revolve readily. The new fire- 

 bars rest on supports which are themselves cylindrical and 

 hollow; they are supported lengthwise by a plate fixed be- 

 neath the door of the fire-box, and fitting into a neck made at 

 the near end of the bar. AVith this construction, it is affirm- 

 ed, the duties of the stoker are rendered much less important 

 and troublesome, and a very material economy of fuel is ef- 

 fected. The foUowino; advantao'eous features are claimed for 

 it : The layer of coal resting on the grate may be doubled 

 in thickness, thus obviating the necessity of frequent charg- 

 ing and the entry of cold air into the fire-box. The interior 

 of these hollow bars being always visible to the stoker, he is 

 able to observe any choking of the air passages as soon as it 

 takes place. It is only necessary for him then to give the 

 bars a fractional turn with the winch, and a clear surface, free 

 from slag and scale, is presented to the fuel. This is accom- 

 plished without opening the doors and admitting an excess 

 of cold air. The rotation of the bars has the additional ben- 

 eficial efi*ect of clearing the obstructed part and throwing 

 down into the ash-pit the ash and other non-combustible 

 impurities, the retention of which retards combustion. The 

 economy of fuel which is claimed for the new construction is 

 of even more importance than the economy of labor. 



AMERICAN MINIJ^G METHODS. 



One of our Comstock mining engineers, lately returned from 

 a tour of inspection through the mining districts of Germany, 

 communicates to a California daily his conviction that there 

 is no engineering in Germany to compare with that on the 

 Comstock lode, and no mines in which the mechanical appli- 

 ances are so ingenious and effective. He supports this asser- 

 tion by a graphic description of the crude and primitive 

 methods in vogue abroad. He remarks that in the deep 

 mines of Bohemia the hoisting apparatus consisted merely 

 of open tubs, and the operating machinery was so poorly con- 

 structed that he dared not venture to descend. In most of 

 the German mines, he found that the men were compelled to 

 walk up or down to the scene of their labors, either by going- 

 down an incline, or by using long parallel stilts, which move 

 up and down alternately about six feet at a time. The mode 



