940 Transactions of the American Institute. 



A number of engines were entered for exhibition, some four of 

 which were said to be intended as competitors in the practical test. 

 Two were connected to the boilers, and used in the ordinary manner 

 to generate power, during the exhibition. It was intended to test 

 the engines at, or immediately after, the close of the fair, and the 

 various members of the committee, men of great judgment and integ- 

 rity, were agreed on, and invited to be present at an appointed day 

 and hour. This was several times repeated, and on each occasion, 

 either but a portion of the committee were present, or a disagreement 

 with regard to how the tests should be made, rendered the whole pro- 

 ceeding ineffectual. The exhibitors, and nearly all the members of 

 the committee, resided at points from fifty to 400 miles distant, and 

 the repeated postponements was exceedingly inconvenient to all 

 parties. It was not till April, of the present year, that the steps were 

 taken Avhich led to the final trial. At this period Mr. "William Sewell, 

 late cliief engineer in the navy, was invited, in conjunction with the 

 writer, to examine into the affair, and report to the Institute what 

 had better be done. The report urged the necessity of a radically 

 different method; that of allowing one alone to arrange for and con- 

 duct the tests according to his judgment, publicly, and in the presence, 

 if practicable, of a portion or the whole of the committee, but with- 

 out interference therefrom, and that all the results should then be 

 submitted to the committee for a decision. The report detailed a 

 tolerably full programme, with estimates of the expense, &c., which 

 was finally adopted by the Institute, and the writer was employed to 

 proceed on tlie plan therein proposed. After notifying a new com- 

 mittee, the fifth, I think, since the commencement, and spending 

 nearly a week in preparation, the tests were made on the 4th and 5th 

 of June last, spending one day on each engine. The committee pre- 

 ferring to receive a report in which the results slioukl be reduced and 

 compared, as well as also all the notes in their original form, the want 

 of leisure delayed the completion of the report until the 1st of the 

 present month, and the committee have nut at this date (Sej)tember 

 25th), made public their a^-ard. 



The engraving shows the brake apparatus ; the various parts wore 

 constructed at different times, and under the superintendence of dif- 

 ferent parties. It was intended to be equivalent, in its finally per- 

 fected form, to a De Prony friction brake, find was made carj^able of 

 being fitted upon different sized shafts, by simply using for each suit- 

 able cheeks, to fill the space between the boss of the brake wheel and 



