402 



REPORT — 1894. 



Barrus, Boston, 1891, p. 18, and in ' Experimental Engineering,' Carpenter, 

 p. 386. 



VI. The Wire-draiving Metliod. — This was first proposed by Professor 

 Peabody. Mr. Barrus and others have devised modified forms of the 

 apparatus. It depends on the principle that slightly moist steam is super- 

 heated by -wire drawing. Fig. 5 shows Mr. Barrus's arrangement • of the 

 apparatus. The steam passes from a chamber A to a chamber B through a 

 very small aperture {-^ inch in diameter). The full steam pressure is in 

 A, and the pressure in B differs little from atmospheric pressure. Ther- 



FiG, 5. 



mometers t, t, give the temperatures of the chambers. Let t^t^ be the 

 temperatures of the steam before and after wire drawing, and fg the 

 temperature of saturated steam corresponding to the pressure in B. t^ — t^ 

 is the amount of superheating of the steam in B. 



Let /t,, Lj be the liquid heat and latent heat of steam at t^ ; /i^, Lj, cor- 

 responding quantities for steam at ^3. 



/i, -f a:L, =7i3 -f L3 -f 0-48(«.^ - ^3) • 



a;: 



./ig-VfLj + 0-48(<2-<3) 



L, 



' See A Universal Steam Calorimeter. 

 Engineers, 1890. 



By G. H. BarruSj Amer. Soc. Mech. 



