HOT. WATER APPARATUS 



821 



1169 



gas-light jet, placed at the side of each window to supply illumination for night- 

 work. 



The piece is stretched along the whole extent of the gallery, and runs through it in 

 the course of one minute and a half ; being exposed during its passage to the heat of 

 212 Fahr. 



In fig. 1168, A is the iron door of entrance to the hot-flue gallery ; at b is the 

 padding-machine, where the goods are imbued with the general mordant. The speed 

 of this machine may be varied by menns of the two conical drums c c, which drive it ; 

 since when the band c c is brought by its forks and adjusting screws nearer to the 

 narrow end of the lower drum, the cylinder upon the main shaft with the latter is 

 driven quicker; and vice versa. Over D i> the cords are shown for drawing the drum 

 mechanism into gear with the main-shaft band, F, F, E ; or for throwing it out of gear. 

 The pulleys FF carry the bands which transmit the motion to the padding machine. A 

 cylindrical drum exterior to the hot-flue, covered with flannel, serves to receive the 

 end of the series of pieces, and to draw them through the apartment. This mode of 

 drying the padded calicoes requires for each piece of 28 yards three pounds of coal 

 for the furnace when a fan is employed, and four pounds without it. See CALICO- 

 PRINTING. 



HOT-WATER APPARATUS. (Calorifere d'eau, Fr. ; Wasser-Reitzung, Ger.) 

 In the Dictionnaire Tecknologique, vol. iv. we find a description of an apparatus, of 

 late years much employed for heating conservatories, &c., by hot water circulating in 

 pipes : 



This mode of heating is analogous to that by stove-pipes ; it is effected by the cir- 

 culation of water, which, like air, is a bad conductor, but may serve as a carrier of 

 caloric by its mobility. We may readily form an idea of the apparatus which has been 

 employed for that purpose. We adapt to the upper part of either a close kettle, or of 

 an ordinary cylindric boiler A., Jig. 1169, a tube B, which rises to a certain height, and 

 descends, making several sinuosities with a gentle slope till it reaches the level of the 

 bottom of the boiler, to whose lowest part, as that which is least heated, it is fitted at 

 c. At the highest point of the tube F we adapt a vertical 

 pipe, destined to serve as an outlet to the steam which may 

 be formed if the temperature be too much raised ; it serves 

 also for the escape of the air expelled from the water by the 

 heat ; and it permits the boiler to be replenished from time 

 to time as the water is dissipated by evaporation ; lastly, it 

 is a tube of safety. 



The apparatus being thus arranged, and all the tubes as 

 well as the boiler filled with water, if we kindle fire in the 

 grate D, the first portions of water heated, having become 

 specifically lighter, will tend to rise: they will actually 

 mount into the upper part of the boiler, and, of course, 

 enter the tube B F : at the same time an equivalent quantity 

 of water will re-enter the boiler by the other extremity c 

 of the tube. We perceive that these simultaneous move- 

 ments will determine a circulation in the whole mass of the 

 liquid, which will continue as long as heat is generated in 

 the fire-place ; and if we suppose that the tubes, through- 

 out their different windings, are applied against the walls 



of a chamber, or a stove-room, the air will get warmed by contact with the hot 

 surfaces ; and we may accelerate the warming by multiplying these contacts in the 

 mode indicated. 



This calorifere can be employed with equal advantage and with more safety than 

 those with heated air, when it is wished to heat large apartments. In the present case, 

 the temperature of the water, without pressure, in the tubes, must be always under 

 100 C. (212 F.), even in those points where it is most heated, and less still in all 

 the other points, while the temperature of the flues in air stoves, heated directly by the 

 products of combustion, may be greatly higher. In air stoves, however, the pipes may 

 without inconvenience have a large diameter, and present, consequently, a large heat- 

 ing surface ; whereas, with the water calorifere, the pressure exercised by liquid upon 

 the sides of the tubes being in the ratio of the surfaces, we are obliged, in order to 

 avoid too great pressure, to employ a multitude of small tubes, which is expensive. 

 Lastly, if the hot-water circulation is to be carried high, as may be often necessary in 

 lofty buildings, the pressure resulting from the great elevation would call for propor- 

 tional thickness in the tubes and the boiler ; for these reasons it appears that water 

 cannot in all cases be advantageously substituted for air or steam in the applications 

 above stated: yet this mode of heating presents very decided advantages where it is 

 needed to raise the temperature a small number of degrees in a uniform manner. 



