206 ANNUAL OF SCIENTIFIC DISCOVERY. 



coal, or of anthracite coal as above, evaporates 14,457 pounds of water 

 from 212. The result with Baker's furnace as above stated is " three 

 pounds less," or 11.45. Hence the water in this case has been reduced 

 to 212 F. 



" This," continues the notice, " is the greatest amount of water 

 evaporated by one pound of coal, in a boiler, ever recorded." This 

 assertion may be true of " a boiler " heated by Baker's furnace at the 

 Crystal Palace, but it is not true when applied to boilers heated by 

 variously formed furnaces for the last ten or fifteen years, both in 

 England and in this country. 



Lb. of Lbs. ofWatgr 



Coal. from 212. 



It is not true of " Cornish boilers " ; for with these, Henwood & 

 Parkes, Civil Engineers, in England, before 1840, evaporated 

 with 1 .... 11.78 



It is not true of a Locomotive boiler , on the worst plan , for with 

 this on board Steamer Anthracite, heated by Player's furnace, 

 in 1840, Dr. Schafhaeutl and Bevan, C.E., evaporated with . 1 .... 12.40 



Parkes and Manby, with the same boiler and furnace, on board 



Anthracit . " 1 12.70 



It is not true of Dr. A. A. Hayes' Battery of four boilers, for with 

 these Hayes evaporated, in 1839. for days together, with . 1 .... 11.83 



It is not true of the Upright boilers of James B. Francis, Esq., C.E. ; 

 for with this Francis evaporated, in 1841, at the Massachusetts 

 Mills, in Lowell, in four days, with 1 .... 12.015 



It is not. true of a Battery of 4 boilers, on Hayes' plan ; for with 

 these the undersigned evaporated, at the Print Works of the 

 Merrimack Man. Co., in 1840, in 13 days, of 12| hours each, 

 with - . . . . 1 .... 11.85 



It is not true of Nest-boilers ; for with this the undersigned 

 evaporated at the M. M. Co. Printery, in 1840. in 3 days, with 1 .... 11.59 



It is not true of a Tubular boiler ; for with this the undersigned 

 evaporated, in 1840, at the M. M. Co.'s Printery, in 6 days, 

 with .... 1 .... 11.96 



It is not true of an improved Cornish boiler ; for with this de- 

 vised and erected in 1840 at the M. M. Co.'s Printery, the 

 undersigned evaporated in 5 days, or 51 i hours, 11.57 Ibs. of 

 water, trom the initial temperature of 75 with 1 Ib. of coal, 

 or with 1 13.10 



The maximum evaporated by Parks on board the Anthracite, 

 was with 1 .... 13.35 



The maximum evaporated by self with Hayes' battery was with 1 .... 13.69 



The maximum evaporated by self with Improved Cornish, was 

 with , . . . 1 ... 13.60 



The average for several days together, by self, with Improved 



Cornish, with 1 .... 13'50 



ON COHESION OF FLUIDS, EVAPORATION AND STEAM-BOILER 



EXPLOSIONS. 



The following paper was read at the American Association, Cleve- 

 land, by Lieut." E. B. Hunt, U. S. A. 



I now wish to present a simple exposition of the mechanical theory 

 of cohesion in fluid masses, and from this to deduce the structure of 

 a fluid surface, showing that its cohesive strength is much less than 

 that of the interior layers. This result furnishes a clear and direct 

 explanation of the great fact of evaporation, and shows why, in all 

 cases, even in ebullition, evaporation is a strictly surface phenome. 

 non. Hence follows an explanation of one of the chief causes of 

 steam-boiler explosions, and the easy suggestion of a very practical 



