148 &af e1 y °f Steam Boats. 



doubles and redoubles the expansive force of the steam, and that it 

 requires very much less fuel and time to produce this 30 degrees 

 more heat, than to produce the preceding 212°. 



As explosions have not been confined to high pressure engines, 

 and as the effects have been so tremendous, it has been supposed 

 that the red hot iron of the flue must sometimes decompose a por- 

 tion of water into its constituent gases, (hydrogen and oxygen). 

 But it does not seem to be necessary to resort to this supposition to 

 account for the effects, if we consider the amount of the force sud- 

 denly liberated by the disruption of the boiler. It must be equal to 

 the outward pressure on a square inch of the safety valve, perhaps 

 never less than 20 lbs., multiplied by every square inch of the inter- 

 nal surface. The displacement of the boiler with such surprising 

 violence may be accounted for from the recoil or reaction of the 

 force from the first considerable resistence it meets with ; as well as 

 by the expansive force in the direction it takes. Thus when the 

 Hoboken boat exploded, I am told the boiler was thrown upwards 

 the rupture being at the under side. That of the Helen McGregor 

 bdng towards the stern, the boiler went over board through the bow 

 of the boat. Had the forward end burst, it might have been thrown 

 as far as the cabin. The boat may be so injured as to immediately 



•the force driving some part of the machine through the bot- 

 tom or side ; or the shock may start the planking. In two instances 

 the boat has sunk. The danger of this must be greater when the 

 boilers are below, than when on deck. 



Every one will admit that it will be for the interest of owners, 

 masters, and men, to take the utmost care. But the danger is inher- 

 ent in die nature of the power, and it is greater than that from neg- 

 ligence. One fact alone proves this : that the safety valve has not 

 been a sufficient protection in either of the melancholy instances of 

 explosion that have taken place. What is the inference ? It must be 

 that the boiler, though up to that time strong, has some how become 

 too weak to hear an expansive force below what it was intended to 



contain ; or else that somehow that force has become suddenly so 



great that th§ safety valve cannot give vent to the steam. 



If then there can be no perfect assurance of safety in steam boats, 

 and so far as depends on fidelity and judgment, much confidence 

 must be reposed in individual laborers, there can be no safety but in 

 keeping out of the reach of the explosion, should it happen ; but this 

 can hardly be done, if in die same boat* My opinion, long since 





