44 



HOT VTATER APPAR ATI'S, 



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o 



Q 



it, to which it is intended to circulate the water, and will be readily 

 understood by a reference to the annexed diagram. 

 In tliis figure c, is a section of the fire place, 

 which, instead of having a common boiler over it, is 

 surrounded by cast iron tubes. The uppermost of these 

 tubes communicates, by means of the upright tube by 

 with the open vessel e, and the lowermost is connected 

 in a similar manner by means of the tube d, with one 

 or any number of tubes under the level of the boiler 

 at e. The uppermost of the tubes at e is connected 

 by the tube /, with the open vessel c. Now, all these 

 tubes being so connected as to admit of water circu- 

 lating freely through them, when a fire is made in a, 

 the heated water ascends by its refraction into the 

 open vessel c, and its place in the tubes round the fire 

 is supplied by the colder water from e through the 

 heated water descending to supply its place from the 

 open vessel e, by the tube/I The limits of the depth 

 to which the water will circnlate below, is that of the 

 height of the open vessel above. To produce this cir- 

 culation, it is nor necessary that the water should boil, 

 for as every heated particle will ascend to the open 

 vessel c, its place must be supplied by a cold particle 

 from d. VTlieii the fire is urged so as to raise the 

 water in the open vessel nearly to the boiling point, the circulation goes 

 on with the greatest rapidity. The substitution of tubes round the fire 

 for a boiler over ir, is by no means necessaiy for the success of this plan, 

 though by rubes rhe rapidiry of rhe circulation is greatly increased. Any 

 close Hjoiler wirh rhe rube b attached to its cover, and communicating 

 with an open vessel fixed at any height, such as c, having another tube 

 similar to / fixed to ir, will circular e rhe heated water from snch vessel to 

 a point below the borrom of rhe boiler, nearly equal to the balance of 

 atmospheric pressure, or say. rhiiry feer below ir. 



The next in order of rime and celebrity which we think worth noticing 

 here, is that of Perkin's. and consists in circulating water in hermetrically 

 sealed tubes, and these of a veiy small size. This plan consists of a coil 

 of wrought iron tubes about one inch in diameter, which serves the pur- 

 pose of a boiler, the fire being made in the centre of the coil, not in 

 immediate contact wirh them, but separated by brick work, over which 

 the heat passes and circulates in the flue, which also contains the pipes. 



