L. MECHANICS AND ENGINEERING. 511 



L. MECHANICS AND ENGINEERING. 



UNITED STATES COMMISSION ON IKRIGATION, IN CALIFOENIA. 



Congress, at its last session, passed an act providing for a 

 board of commissioners to report a system of irrigation for 

 the San Joaquin, Sacramento, and Tulare valleys, in California. 

 The board is to consist of two engineers of the army and one 

 officer of the Coast Survey, who are authorized to associate 

 with them the chief of the Geological Survey of California, 

 and one other civilian distinguished for his knowledge of the 

 subject ; these five to constitute the board, whose duty it 

 shall be to make a full report to the President on the best 

 system of irrigation for said valleys, with all necessary plans 

 and details, engineering, statistical, etc., to be transmitted to 

 Congress at its next session. The Secretary of War is to 

 furnish subsistence and transportation to the board while in 

 the field, and the civilian members may receive a compensa- 

 tion not to exceed $2000 each. Acts of Co?igress, JVb. 80. 



MAREZZO MARBLE. 



An article known as Marezzo marble, lately introduced 

 into England, promises to be a valuable addition to the orna- 

 mental substances used in the arts, the appearance of true 

 marble being very closely imitated, and the resulting ma- 

 terial being very easily worked and very durable. The im- 

 itation of diff*erent colored veins in the marble is efiected by 

 taking skeins of silk, stee23ed in suitable colors, and laid in 

 proper combinations upon a polished glass plate. Upon this 

 is poured, to a depth of about one tenth of an inch, a quan- 

 tity of fine cement, mixed with water, of a suitable body 

 color, and the skeins of silk are removed before solidification 

 ensues, leaving their representation in the colored mass. The 

 thickness of the artificial marble is increased by backing it 

 w4th a cement of a somewhat coarser quality, and a still 

 coarser quality of cement is applied for the purpose of taking 

 up the superfluous moisture. The whole will set in a very 

 short time, and allow the glass slab to be raised on end, and the 

 general eflfect to be exhibited. When completely dry, the slab 



