PROCEEDINGS OF THE. POLYTECHNIC ASSOCIATION. 597 



formly. This process has been adopted in the French arsenals. 

 Entire ships have thus been carbonized. Until recently, there 

 was a difficulty in applying this process except in towns supplied 

 with gas for illumination. A son of M. de Lapparent has over- 

 come it by using a portable lamp, so constructed as to burn com- 

 mon and cheap hydro-carljons. The oil is so conducted by a single 

 cylindrical wick of large diameter, placed horizontally at the side 

 of the reservoir ; in the center of the wick is a pipe communicat- 

 ing with a pair of bellows, worked by a treadle ; a metallic chim- 

 ney, pierced with holes at its base, completes the apparatus, which 

 produces a flame quite as intense as that of the gas burner. With 

 this arrangement, an operator can carbonize about twenty-seven 

 square feet of oak, or twenty-two square feet of pine per hour, 

 with a very small expenditure of oil. The French railway com- 

 panies have availed themselves of the process, and apjily it to most 

 of their wooden structures. In this country, crude petroleum 

 can be made available for carbonization ; aud thus cheapened, the 

 process should be applied in all cases where the durability of 

 Avood is of the first importance. 



OCEAX CURRENTS. 



J. Stanley Grimes, Esq., continued his remarks on the cause of 

 ocean currents and the result of their action in depositing sedi- 

 ment. On the sinkino; of the ocean's floor beneath the Aveicht of 

 the accumulated sediment, he said that the central portions of the 

 oceans have sunk, and that their borders have risen, is proved 

 beyond all question. The evidence accumulated upon this sub- 

 ject by Darwin and by Dana, in connection with the coral reefs 

 and islands, is highlj^ instructive. It shows that the depressions 

 have been gradual and continuous, in the same localities, from the 

 earliest geological ages. Many of the geological formations also 

 afford the most positive proofs that they were deposited while the 

 crust of the earth — the ocean's floor — was slowly subsiding. Mr. 

 Lycll, in his Manual of Geology says: 



"The structure and organic contents of some of the ancient 

 marine formations, point to the conclusion, that the floor of the 

 ocean was slowly sinking at the time of their origin. The down- 

 ward movement was very gradual, and in Wales and the contigu- 

 ous parts of England, a maximum thickness of 32,000 feet (more 

 than six miles) of carboniferous, devonian and silurian rock was 

 formed, while the bed of the sea was all the time continuously aud 

 tranquilly subsiding. The sea remained shallow all the Tvhile." 



