Report of the Committee ok Steam Boilers. 73 



The fires will be attended to by the exhibitors, and managed as they 

 may think proper. The water level will be fixed at a proper height, 

 and a thread tied around the gauge-glass at that point, its height 

 above the bottom of the glass being recorded ; and the water will be 

 kept, as nearly as possible, at that point. • At the termination of 

 twelve hours from the commencement of the trial, the stop valve will 

 be shut, and the fires hauled. The exhibitor may, at his discretion, 

 allow his fires to burn down toward the close of the trial ; and will 

 be credited, in any case, with the fuel remaining on the grate. 



A Davis recording gauge, and, if possible, an Edson gauge, will 

 be attached, and their record handed to the Committee at the close of 

 each test. 



The Committee will, at their own discretion, decline to proceed in 

 any test where all the prescribed preliminaries have not been com- 

 plied with ; and will, should they consider it proper, throw out any 

 test which has evidently not been conducted as directed. 



After the trials all apparatus will be again tested, and measurements 

 of heating and grate surfaces revised. 



Yery respectfully, 



K. H. THUKSTON, 



Chairman. 



Supplementary Letter. 



Fair of American Institute, 

 November 9th, 1871. 

 To the Superintendent of Machinery : 



Sir. — It having been found necessary to change the position of the 

 meter which is to measure the quantity of injection water used during 

 the proposed test of steam-boilers, and as it is now arranged so as to 

 measure the entering stream, the following method of operation with 

 respect to the supply of injection, etc., will be adopted : 



At the beginning of each trial the injection will remain shut off 

 until the temperature of the surface-water in the tank has reached one 

 hundred and fifty (150) degrees Fahrenheit, when the injection will 

 be turned on. 



At the close of the test, after the steam has ceased entering the 

 condenser from the boiler on trial, the injection will remain open 

 until it is found that the water entering and that leaving the tank 

 have about the same temperature, and evidence is thus given that all 

 of the heat received from the boiler has been taken away and measured. 



