476 PROCEEDINGS OF THE AMERICAN INSTITUTE. 



Prof. Jackson replied, there was no difference in opinion among geolo- 

 gists in regard to the stratified rocks ; they were deposited at the bottom 

 of lakes and oceans. BiJt some of these, since their deposit, have been 

 raetamorpliozed or changed to a crystaline structure, and there has been 

 much discussion in relation to the agencies by which this metamorphism 

 was efiFected. Tt seems to me that M. Daubree has cut the Gordian knot, 

 aii3 has shown that the crystalization was produced mainly by the action 

 of superheated water, that is, water heated above the boiling point. This 

 can be done, as you arc aware, by confining water under pressure. M, 

 Daubree enclosed various substances in strong iron tubes, filled the tubes 

 with water, closed them tightly with screw plugs, and had them built in 

 the brick work of gas furnaces, where they were exposed constantly to a 

 high temperature for several weeks or months. Wood thus enclosed was 

 first melted and compressed into a globular mass, and if longer exposed, 

 was finally converted into anthracite coal. Glass was decomposed and its 

 silex formed into beautifid quartz cr^^stals. M. Daubree found that if 

 sufficient time was allowed, it was not necessary even that the water 

 should be superheated. The warm springs of Plombiers were used for 

 baths by the llomans, who led the water through aqueducts constructed of 

 brick or cement. On examining the materials of these aqueducts, which 

 have been subjected to the action of warm water for 2,000 years, it was 

 found to be transformed into the same crystaline minerals that occur in the 

 metaniorphic- rocks. 



Air AND Steam Engine. 



Mr. A. L. Murdock, of Boston, exhibited diagrams illustrating the com- 

 binations used in P. Shaw's patent union air engine. In this arrangement 

 the products of combustion are used as a motor in combination with steam. 

 The air which feeds the fire is forced in and after combining with the car- 

 bon and hydrogen of the fuel is made to move a piston in a similar method 

 to that employed in the Roper air engine. After the air has passed from 

 the piston, it expends its heat upon a boiler containing water, and the 

 steam thus produced passes into combination with the products of combus- 

 tion and assists in moving the piston. Mr. Murdock stated that this engine 

 had been favorably noticed by the Boston Academy of Science and Art. 

 and they had given several hundred dollars to enable him to complete his 

 engine. 



RuMFORD Prize Fund. 



The Chairman requested Dr. Jackson to give a history of the Rumford 

 Prize Fund. 



Dr. Jackson— Count Rumford, formerly Benjamin Thompson, of New 

 England, left a bequest to the American Academy of Arts and Sciences of 

 Boston, the oldest scientific association in the country, to be- devoted to 

 improvements in light and heat, especially such as should be useful to the 

 mid41e classes of the people. The academy unfortunately has not displayed 

 proper activity in discharging the duties of this trust. For forty years the 

 only prizes bestowed were the gold and silver medal awarded to Dr. 

 Robert Ilare, the distinguished American chemist, for the invention of the 

 ox3'-hydrogcn or compound blow-pipe, in which hydrogen and oxygen com- 



