L. MECHANICS AND ENGINEERING. 435 



of ascending and descending on these is to step from one to 

 the otlier, as each ascends or descends, where a misstep would 

 be attended with fatal consequences. His remark that in the 

 Comstock the men went down to the lowest levels and came 

 up in two minutes without the slightest exertion was re- 

 ceived politely but incredulously. The character of the min- 

 ing tools employed is criticised in the same uncomplimentary 

 strain, and the assertion is made that an average day's work 

 upon the Comstock would seem incredible to the miners of 

 continental Europe. 



STATISTICS OF STEAM. 



Statisticians calculate that there are now in work some 

 200,000 steam-engines, with a total power of 12,000,000 horses, 

 corresponding to the muscular strength of 100,000,000 men. 



CASING FOR STEAM-PIPES, ETC. 



The following composition is recommended by Dr. Spring- 

 miihl for coating steam boilers, pipes, etc., by laying it on 

 from three quarters of an inch to one and a quarter inches 

 thick, according to the size of the object : White pipe-clay, 

 30 parts ; fire-clay, 25 parts ; powdered charcoal, 20 parts ; 

 rye-flour, 7 parts ; boiled linseed-oil, 5 parts ; cow's urine, 3 

 parts. 



CASING FOR STEAM-PIPES. 



The German Journal of Woolen 3Ianiifactitres gives the 

 following for casing steam-pipes : Mix fuller's earth, that has 

 been used and collected in sinks for this purpose as well as to 

 prevent the filling of streams, with fully the same quantity 

 of coal-ashes, and add to the pasty mass as much calf's hair 

 as it will take up. Before laying it on add one eighth its 

 quantity of calcined gypsum, and lay it on in thin coats. If 

 the first layer does not adhere well, unused fuller's earth may 

 be used for it. 23 (7, VII., 50. 



ANTI-FOULING COMPOSITION. 



It is said that the copper sheathing of the two royal En- 

 glish yachts Alberta and Elfin v/ave in 1873, at the command 

 of the Admiralty, painted with Jesty's patent anti-foul ing 

 composition, in order to prevent the adhesion of sea-grass and 



