74 Transactions of the American Institute. 



During this latter interval, the temperatures of injection and of 

 discharge will be measured at as frequent intervals as the judges or 

 their representatives may consider necessary for accurate determination 

 of the quantity of heat passing off. 



The tank for measuring the water of condensation having been 

 found to leak seriously, you will substitute for it a vessel in which the 

 water may be caught and accurately weighed. 



You will see the precaution taken to open the injection-cock as little 

 as possible, in order to use the least quantity of water consistent with 

 complete condensation of steam. 



Very respectfully, yours, 



K. H. THUESTON, 



Chairman^ for the Committee. 



The Eoot boiler was first connected with the condenser, and its 

 trial commenced, November 10th. But it was found that the boiler 

 could furnish more steam than the safety-valve, through which the 

 steam was intended to blow off into the condenser, could pass. It 

 became necessary, therefore, to allow the steam to pass directly through 

 a stop-valve into the condenser. This interrupted the trial for the 

 day, and advantage was taken of the opportunity thus offered to 

 remedy all of the minor defects that had been discovered. 



On November 13th, the trial of the Eoot boiler was made without 

 mishap, continuing through twelve hours, as proposed ; on the 14th,. 

 the Allen boiler was tried ; on the 15th, the Phleger ; and on the 

 16th, the Lowe. After a series of mishaps, the Blanchard boiler was 

 also finally tested successfully on November 21st. 



We annex the record, given by the logs, in exhibits A, B, C, D, and 

 E ; and before proceeding to discuss these results, will give a brief 

 description of the competing boilers. 



Description .of the Eoot Boilek. — (Plate 1.) 

 This boiler consists essentially of eighty (80) wrought iron tubes, 

 each four (4) inches in diameter, and nine (9) feet long. These tubes 

 are set in brickwork, at an angle of about 30° from the horizontal. 

 The tubes are connected together by the system of triangular plates 

 and crowfeet represented in figures 1 and 2 ; the joints being formed 

 by the aid of rubber grummets. The boiler has a steam drum, 

 eighteen (18) inches in diameter, and six and three-quarters (6f) feet 

 long. The superheating of the steam is effected in the upper portion 

 of the boiler, where the tubes are, like those forming the water space, 



