168 I'ROCEEDINGS OF 



2. In Wagon Boilers. 



New-Castle bituminous coal, by Watts's trials, 9.63. 

 Bituminous coal, variety uncertain, 8 sets of experiments, 8.76. 

 Bituminous coal, Parke's experiments for six months, 10.28. 



3. In Cornish Boilers. 



Welsh coal, trial by Henwood, 11.62. 



"Welsh coal, experiments cited by Henwood, 11.78. 



4. In a Marine Boiler on board the Steamer African. 

 Heaton bituminous coal, 8.15. 



5. In four Cylindrical Boilers on Hayes's plan. 

 Anthracite }, bituminous dust i, 11.83. 



6. In a plain High Pressure Boiler. 

 Scotch bituminous coal, by Pigfe, 7.74. 

 Anthracite, kind uncertain, 10.10. 



7. In Player's Boiler for using Anthracite. 

 Anthracite, by Schaufbautl's trials, 12.40. 

 Anthracite by Parke's and Mauley's trials, 13.25. 



8. In Dana's improved Cornish Boilers, newly altered. 



Anthracite of Beaver meadow, 15.56. 



Anthracite of Beaver meadow, maximum of Dr. Dana's results, 16.64. 



Though important general conclusions can be derived from the foregoing facts, 

 yet, as several circumstances highly necessary to render the results comparable, 

 have been very various in the several experiments, it is evident that we yet want 

 an extensive series of operations on tlio several varieties, made in a manner which 

 shall render them true indices of the heating powers of the several kinds of coal. 



PLAN OF EXCHANGES SUBMITTED BY DR. E. FOREMAN. OF 



BALTIMORE. 



The subject of exchanging specimens of natural history having been already 

 forced upon the attention of the National Institution, I take the liberty to submit 

 a few considerations, being the oulUncs of a plan wliicii I have found to yield 

 profitable results in my own practice. The necessity of repaying those naturalists 

 who have contributed native or other species to tlie cabinet is obvious, and equally 

 so the advantages to be derived by distributing the great numbers of the same spe- 

 cies, which the Institution has accumulated and will continue to accumulate. Hav. 

 ing studied the subject of conchology for a few years, in a private way, in the leisure 

 time afforded by a long college summer vacation, and acting under the desire and for 

 the purpose of enlarging my collections, I adopted a system by which I believe that 

 the expenditure of time, money, and exertion, will yield the greatest results. 



