,'\M Mechanical Science, ' " 197 



found mineral substances, as a piece of slate, mi^ht be substituted 

 for the oro^anized tissues ; this beingr the case, the opinion which 

 refers such effects to a general cause, as capillary attraction, ac- 

 quires more probability. 



3. Novel Use of the Plough. — Mr. Bruckmann states that he has 

 long thought the plough might be used in levelling roads and 

 clearing the foundations for fortifications. In 1824 he had an 

 opportunity of applying it in the construction of a canal required to 

 furnish a motive force for the service of the rock-salt works of Fried- 

 richshall. The bed was to have a section of 700 square feet, and it 

 had been calculated that the excavations would require 200 men for 

 two years, whereas the king of Wurtemburg wished it to be done 

 in one year from the spring of 1824. 



Three ploughs were employed; the first had two handles, a 

 coulter, and a share, the latter being in the form of a wedge. This 

 plough was preferred in the beds and gravelly grounds ; and it was 

 found advantageous to give it an oscillatory movement by the 

 handles during its progress. Drawn by eight horses, it could turn 

 up 25,000 cubic feet of an argillaceous soil, in three hours ; with 

 ten horses it turned up 19,800 cubic feet of a gravelly soil, in the 

 same time. This plough was tried in 1815, against fifteen others 

 of the ordinary kind, in the construction of a watercourse for a 

 mill ; all the fifteen were quickly broken by the work. 



The second plough had two handles and a coulter, but the share 

 had only one cutting edge, which was rounded and with an ear. It 

 was made five times as strong as an ordinary plough, and suc- 

 ceeded well in compact and argillaceous soils, where, with eight 

 horses and four men, it moved 48,000 cubic feet of earth in three 

 hours. In case of fracture ten minutes sufficed to change the 

 coulter and share, and, during the work, 2,300,000 cubic feet of 

 earth were loosened by it. 



The third plough was smaller and fighter, it had two handles, a 

 coulter, an ear, and a share, the latter lance-shaped. It was used 

 for excavating the sides of the canal, on which the horses attached 

 to the first plough found it difficult to walk because of the inclina- 

 tion. It was worked by ten or twelve men. 



To establish an accurate comparison between the work of these 

 ploughs and that done by the pickaxe and spade, a piece of ground 

 was wrought solely in the latter manner by six strong working men. 

 The result of a long trial was the breaking of 150 cubic feet of 

 ground by each man in nine hours. Comparing this result with 

 the work of the ploughs, the following are the results: — ^The first 

 plough did the work of 477 men, the second of 960 men, and the 

 third that of 50 or 60 men. The canal was finished on April 30th, 

 1825, the ploughs having saved 32,000 days, according to the 

 work-day of a labourer. — Bull. Univ. D. vii. 343. 



