Safely Apparatus for Steam Boats. 319 



should ihus, by borrowing from our brethren abroad, be provided 

 with a certain remedy against explosions caused by the circumstances 

 we have endeavored to explain, and also against the bursting of the 

 boiler from an accumulation of steam within, should any accidental 

 derangement of the common safety valve prevent its action. This de- 

 vice would be of the greatest value if applicable to steam boat boilers, 

 for, being entirely without the control of the engineer, caution would 

 be produced by the fact that ajny attempt to raise the steam above 

 the proper pressure, or any inattention to the supply of water within 

 the boiler, would be immediately made known to the captain and 

 passengers by the noisy efflux of steam through the aperture opened 

 by the melting of this tell-tale plate. If the plate were placed within 

 sight of the passengers, the only means of an improper kind, to 

 which the engineer could resort, to prevent its fusion, (sometimes 

 practised in the stationary engine in France, according to M. Arago,) 

 viz. keeping it cool by the apphcation of water to its surface, would 

 be entirely cut off. 



The reason why this plate has been considered inapplicable to 

 steam boat boilers, in general, is obvious ; when the plate melts, all 

 the steam must escape from the boiler, and the apparatus must cool 

 before it can be replaced by a similar plate ; this sudden desertion of 

 the prime mover of the engine might, in certain cases, put the lives 

 of the passengers in almost as great jeopardy as an explosion ; in- 

 stances, in an exposed navigation, will readily occur on reflection, 

 such as a boat on a lee-shore, &c. In all cases such a desertion 

 would be attended with very great inconvenience. 



The remedy for this, and one which simplicity and consequent 

 ease of application seem to recommened very particularly, will now 

 be stated. If, as is hoped, this apparatus shall be found to remove 

 every objection to the use of the fusible plate in the boilers of steam 

 boats, it will insure the exemption of passengers from a portion at 

 least of ihe dangers to which they are now so often exposed. 



The method, vv'hich I would propose, is to combine the fusible 

 plate, with the ordinary safety valve. Such a plate affixed to an 

 opening of a proper size, in the boiler, as near as may be practicable 

 to the highest line which is exposed to the direct action of the fire, 

 is covered with a hollow cylinder, of a greater diameter than the 

 aperture covered by the plate, the base of which presses upon the 

 edges of the plate, while the top is arranged as the seat for a coni= 

 calj or flat valve, of the ordinary kind ; this valve will be habitually 



