Root’s boiler, the trial of which occupied the first day, blew steam from the open try-cock, from water at 46 degrees Fahrenheit, in sixteen minutes from lighting the fire. Next morning our boiler blew steam from water at the same temperature, in twelve minutes, and Mr. Root holding his watch could not resist the ejaculation, “Wonderful boiler!” The Allen boiler, burning 13.88 pounds of coal per square foot of grate per hour, evaporated one cubic foot of water per hour from each 17.41 square feet of heating surface. Root’s boiler, burning 11.73 pounds of coal per square foot of grate per hour, required 23.59 square feet of heating surface to evaporate one cubic foot of water per hour. Our stronger draft, 13.88 against 11.73, accounted for 3.2 pounds of the above superior evaporative efficiency, leaving 3 pounds to be accounted for by the more rapid circulation in the Allen boiler. The great value of the inclination of the tubes was thus established. The report contains this sentence: “The Committee desire to express their appreciation of the excellent general arrangement and proportions which gave to the Allen boiler its remarkably high steaming capacity.” The reader will observe in the plan of this boiler the pains taken to maintain as far as possible parallel currents of the heated gases through the boiler, and taking the flues off at the bottom, thus bringing all the heating surfaces at the same distance from the furnace into approximately equal efficiency. RESULTS OF THE COMPETITIVE TRIAL OF STEAM BOILERS AT THE FAIR OF THE AMERICAN INSTITUTE, NOVEMBER, 1871. ---------+-----------------+--------+ | | | | Square Feet. | | +--------+--------+ | | | | | | | | Ratio | | | | of | | | | heating| | | | surface| | | | to | | Grate | Heating| grate | Name. |surface.|surface.|surface.| ---------+--------+--------+--------+ | A. | B. | C. | Root | 27 | 876¹⁄₂ | 32.5 | Allen | 32¹⁄₄ | 920 | 28.5 | Phleger | 23 | 600 | 26.1 | Lowe | 37³⁄₄ | 913 | 24.2 | Blanchard| 8¹⁄₂ | 440 | 51.8 | ---------+--------+--------+--------+