98 



MR. J. P. JOULE ON TESTING STEAM BOILERS. 



rise of pressure^ it was evident that no permanent alter- 

 ation of figure or incipient rupture had taken place. 



In the so-called testing by steam pressure it is impos- 

 sible to be sure that a boiler has not thereby suffered 

 strain ; and there is therefore no guarantee that it will 

 not burst if subsequently worked at the same or even a 

 somewhat lower pressure. It is to be hoped that this 

 practice^ objectionable on account of its uselessness as 

 well as its danger, will be immediately abandoned. 



In the ordinary hydraulic test the water is introduced 

 discontinuously, and therefore the pressure increases by 

 successive additions^ rendering it difficult to be sure that 

 strain is not taking place. This system also requires the 

 use of a special apparatus. 



The plan I recommend is free from the objections which 

 belong to the others, and the facility with which it may 

 be employed will probably induce owners to subject their 

 boilers to those periodical tests the necessity for which 

 fatal experience has so abundantly testified. 



Observations of Pressure every minute. 



ElPEEIMENT I. 



Experiment II. 



Temp'= at commencement, 97 ° F. 



Temp'' at commencement, 126° P. 



Pressure in lbs. 



Pressure in lbs. 



i"o 



o* 



2-9 



2-8 



4-4 

 6-0 



5-9 

 8-8 



V7 



I2'6 



9 "05 



i6-i 



II- 



20-8 



12-35 

 13-85 

 15-1 

 i6-8 



26-1 



31-8 



38- 



44* 



20-I 



24-8 



49-9 



54-8 



31" 



37-2 

 44-2 



59"4 



63-8 



Temperature at conclusion, 1 39° F. 



5^'4 

 58-2 

 63- 



Temperature at conclusion, 126° ]?. 





