> i 
4 7 On the means of safety m Steam Boats, 
Experience has taught us the serious lesson, that there are times 
how the usual means of safe-guard in steam boats would be una- 
vailing. Practice has also established extensively the use of that 
form of boiler which has flues within; and it may not be reasonable 
to expect them to be changed, as this would involve much expense. 
{ think this invention will, as to the most formidable cause, make 
them safe. » 
Whenever the occasion of alarm or approach of danger occurs, it 
will be important to supply water liberally without delay to the boiler, 
whether the engine be in motion or stopped. Then the supply- 
chamber deseribed in Mr. Renwick’s treatise and represented plate 
Il, fig. 2, (which originated with me some years ago) is val adapted 
to this purpose. 
I am well convinced there can be no defence but prevention. 
The effects of the explosion at McQueen’s foundery in this city last 
summer, serves to show that no bulwark that could be erected on 
e side of a steam boat, would avail as a protection, but might, by 
shattering the side, endanger her sinking. 
‘When we shall have superadded safety to speed in our steam 
packets, this branch of navigation will be advanced nearly to its prac- 
tical perfection. 
- With the highest respect, I am your friend and humble servant, 
J. L. Sunnivan. 
copy. 
Specification of a new and useful improvement or invention to 
guard against the danger of explosions, denominated the Alarm Bell 
Float and Phonic Guage of Steam Boilers; invented by John L. 
Sullivan, Civil Engineer; described as follows, viz. 
The first object of this invention is to cause the water itself to give 
the alarm, when becoming dangerously low. 
Theasecond object in importance is to use bells or metallic trian- 
gles, or other soncrous bodies, within the boiler to ascertain where —_ 
the surface of the water is within certain limits. 
The principle of their operation is founded in the facts whieh ex- 
periment has established, that bells or sonorous bodies emit a louder 
sound in compressed air, than in the atmosphere—that the surface of 
water is favorable to conducting sound,, and that it will pass through 
