868 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



globes at 600 pounds, a new pair having been substituted and 

 trial repeated, fracturing again at same place, at 625 pounds 

 pressure. 



Second^ a similar section set in brick work was filled three- 

 fourths full with cold water and stopped close, except a small 

 pipe leading to a high pressure gauge, the steam was raised to 

 875 pounds, at which pressure steam and w\ater escaped freely ; 

 the gauge depressing gradually rested finally at 300 pounds, and 

 the escape ceased ; brisk firing was continued, the steam occasion- 

 ally escaping, no rupture could be eflfected. On the section being 

 removed for inspection, it was found that under the intense heat 

 the tie bolts of the lower series of globes had elongated, opening 

 the joints and permitting the escape of the contents until by 

 depressed temperature the contraction of the tie rod closed the 

 seam. The section presented on close inspection no injury, and 

 beyond the necessary slight turning of some of the tie nuts, 

 nothing has been done to this section, as good to-day as before the 

 trial. 



Third, similar trial wdth two sections regularly set in brick 

 work. In this case there being no safety valve, steam, after 

 acquiring a pressure of 125 pounds, was allowed to escape l)y the 

 blow-ofi' cock, keeping the pressure at 100 pounds, while fireing 

 briskly ; after the water got below the lowest gauge cock, a slight 

 leak of steam took place at a joint in the left hand section, but 

 suddenly closed ; another leak then appearing in the right hand 

 section, this also closed in a few minutes, no other leak occurring. 

 The water boiled aw^ay, the globes above the bridge wall becoming 

 red hot, and yet the gauge indicated 30 pounds from some w^ater 

 in the lower globes. The boiler sustained no injury. 



Fourth^ a boiler duplicate of the last was charged with water to 

 the upper guage cock, and pressure raised to 90 pounds, blowing 

 ■off freely, and falling to 60 pounds, where it continued with the 

 blow-off open until the boiler was emptied of water ; the fire being 

 kept vigorous for some minutes. The boiler was then rapidly 

 filled with cold water, the stream rising to 100 pounds in thirty 

 minutes, and the boiler was perfectly sound and in no way injured. 



The committee further report: "The experiments described 

 were conducted to determine the safety and durability of the 

 boiler, under unusual and severe usajre. or rather to determine 

 whether au}'^ danger can result from submitting this kind of ])oiler 



