i;8 APPENDIX. 



have been brought out and successfully used for this purpose. 

 It has come to be a practice with many experts to include 

 in the table of results of boiler-tests the percentage of 

 " efficiency," or proportion of the calorific value of the coal 

 which is utilized by the boiler. Specifications and contracts 

 are in some cases drawn up, providing for certain percentages 

 of efficiency instead of a specified evaporation. The analysis 

 of flue-gases is receiving more attention than formerly, not 

 only in our educational institutions, but also in the regular 

 practice of engineers who make a specialty of boiler-testing. 



Your Committee submits a revised Code, termed the Code 

 of 1897. It is substantially the same as the 1885 Code, with 

 such amendments as the experience of the last twelve years 

 has shown to be desirable. 



It is beyond the province of the Committee to recom- 

 mend instruments of particular makers for obtaining the 

 quality of the steam, the calorific value of the fuel, or any 

 other data relating to the trial ; but following the practice of 

 the former Committee, individual members have submitted 

 their views (with the approval of the full membership) in an 

 " Appendix to the 1897 Code," signed by their initials. In 

 this appendix are included some of the articles from the 

 appendix to the former Code, which are thought to be of 

 especial value. 



In the matter of instruments for determining the calorific 

 value of fuel, it seems desirable that the Committee should 

 make a recommendation which is as specific as present knowl- 

 edge and circumstances will warrant. It is agreed that some 

 form of calorimeter in which the coal is burned in an atmos- 

 phere of oxygen gas is to be preferred, and it is generally 

 held that the most perfect apparatus thus far brought out is 

 the Bomb Calorimeter, originally designed by Berthelot, and 

 modified by Mahler and Hempel. Several of these instru- 

 ments are in use in this country, principally in the laborato- 

 ries of engineering schools ; but the apparatus is complicated 



