924 Transactions of the American Institute. 



arrangement of disks is to more rapidly lower the temperature of the 

 tube by quickly transmitting the heat of the tubes into the disks on 

 such tubes, so as to extend it over a much larger area of surface in 

 contact with the water ; thus preventing that over-heated condition 

 of the tube which repels water and often throws it into the spheroidal 

 state. Experience proves that a given area of metal at a high given 

 temperature will not produce ebulition as rapidly as double that area 

 having a temperature only half as high, measured from that of the 

 surrounding water. 



Another object of still greater moment is effected by means of the 

 disks, namely : Every particle of steam formed between the disks is 

 immediately conveyed away from the tubes and entirely beyond the 

 limits of the disks ; to which it cannot return to interfere with the 

 further process of boiling. Both water and steam will be carried 

 inward and upward ; the steam will remain in the highest portion of 

 the boiler, while the water at the surface will gradually descend along 

 and near the inner surface of the shell ; and, on its passage downward, 

 will supply every disk with the required quantity of water, thus pro- 

 ducing constant and complete circulation of water in the lower part of 

 the boiler. As the steam generated between every pair of disks is 

 immediately discharged upward^ thus providing room for the incoming 

 water, it is apparent that every portion of each tube, from its bottom 

 to the water line, is rendered effective ; and as metal is a vastly better 

 conductor of heat than water, increased facilities are provided for 

 arresting the heat contained in the ascending gaseous products of com- 

 bustion, and transferring it to the surrounding water ; thus less heat 

 will escape up the chimney, unutilized, than in the case where the 

 tubes used have no covering of disks. Arrangements are being made 

 for ascertaining by experiment the exact amount of water evaporated 

 with a given amount of fuel in two boilers of the same size ; one con- 

 taining plain tubes and the other tubes covered with disks, with the 

 intention of laying the result of such comparative test before this 

 Association at a future meeting. 



Of Steam Heaters. 

 Tubes or pipes covered with disks, as already described, may be 

 used in heating air, for warming purposes, by means of steam. As 

 the disks or plates are, virtually, a series of strengthening bands, the 

 pipe surrounded by them may be made of very thin metal which will 

 permit the heat to pass more rapidly outward. A very compact and 

 effective apparatus may be constructed by arranging a series of verti- 



