328 OftJie Use of Steam 



This steam-tube may either descend within the vessel to 

 which it belongs, or on the outside of it, as shall be found 

 most convenient. If it comes down on the outside of 

 the vessel, it must enter it at its bottom by a short 

 horizontal bend ; and its junction with the bottom of 

 the vessel must be well secured, to prevent leakage. If 

 it comes down into the vessel on the inside of it, it 

 must descend to the bottom of it, or at least to within 

 a very few inches of the bottom of it ; otherwise the li- 

 quid in the vessel will not be uniformly or equally heated. 



When the steam-tube is brought down on the inside 

 of the containing vessel, it may either come down per- 

 pendicularly and without touching the sides of it, or it 

 may come down on one side of the vessel and in con- 

 tact with it. 



When several steam-tubes belonging to different con- 

 taining-vessels are connected with one and the same 

 horizontal steam-conductor, the upper end of each of 

 these tubes, instead of being simply attached by solder 

 or by rivets to the under side of the conductor, must 

 enter at least one inch within the cavity of it ; otherwise 

 the water resulting from a condensation of a part of the 

 steam in the conductor by the cold air which surrounds 

 it, instead of finding its way back into the steam-boiler, 

 will descend through the steam-tubes, and mix with the 

 liquids in the vessels below ; but when the open ends 

 of these tubes project upwards within the steam-conductor, 

 though it be but to a small height above the level of its 

 under side, it is evident that this accident cannot happen. 



It is not necessary to observe here, that, in order that 

 the ends of the steam-tubes may project within the hori- 

 zontal conductor, the diameters of the former must be 

 considerably less than the diameter of the latter. 



