172 [Assembly 



blies and in our steam vessels. This is a matter which legisla- 

 tive action alone can remedy. 



On the river wliere steamboats first floated, at the port wlience 

 they first put out to navigate and cross the ocean, it is proper 

 that the reform should commence, and tliat the American Insti- 

 tute, tlie fostering mother of the arts, should assume to direct the 

 attention of scientific engineers and skilful artisans to this impor- 

 tant matter. 



There are two aspects in which this subject is to be viewed, 

 1. Its principles. 2. The application of them. The supply of 

 pure air requires the removal of tliat which has been breathed or 

 rendered impure by combustion or exhalation from crowded per- 

 sons or other sources. The principle upon which all ventilation 

 is eflected is, first,. that of the horizontal movement as in winds 

 or by the passage of vessels through the air ; and, secondly, of the 

 vertical movements depending upon differences oi specific gravity. 

 The first cannot be relied on as it fails in calm weather and in 

 steam-vessels when they are moving in the same direction and 

 with the same velocity as the wind. 



The difference in the specific gravity of heated and impure air 

 is always suf&cient to produce motion of the air, and furnish 

 adequate ventilation. An erroneous idea prevails with many 

 persons, that an increased proportion of carbonic acid gas, which 

 is very heavy in comparison wdth atmospheric air, being emitted 

 in expiration, the air expired would be heavier than pure air. 

 This is erroneous, inasmuch as the expansion by heat, of the ex- 

 pired gases, more than compensates for the small additional per 

 centage of the heavier element. In their own smoke flues and 

 in the heat of their fires, steamboats possess a most powerful and 

 most effective means of ventilation, depending upon the principles 

 of the greater lightness of heated air. The foul air of their cabins 

 and rooms is pure enough for their fires and may be readily 

 drawn out to supply them. 



It is not the province of the committee to enter into details 

 as to the modes by which ventilation may best be effected ; they 

 content themselves with pointing out some of the most promi- 

 nent defects of the arrangement on board of steam vessels- 



