ZTbe Dalles of flDesfco's Drainage. 277 



feet from each other. These served to ventilate the tunnel and to 

 facilitate the work. The deepest of these shafts, situated on the saddle 

 of Acatlan, has a depth of 92 metres, or 301 feet 9 inches; the shallow- 

 est is 21 metres, or 68 feet 10 inches. 



To give an idea of the labor involved beyond the mere tunneling, 

 it is as well to mention that the quantity of materials required per lineal 

 yard of tunnel was 1800 bricks, 94 cement blocks, 3 cubic yards of 

 mortar, and 70 cubic feet of volcanic stone. 



Maximum discharge through the tunnel = 18 cubic metres, 635! 

 cubic feet. 



When the drainage board took charge of the work, it was executed 

 by day labor both in the canal and in the tunnel, the latter having the 

 larger amounts expended on it. But, shortly afterwards, the contract 

 for the tunnel was let to Messrs. Read & Campbell, of London, who, 

 after having invested a considerable sum in the work, found themselves 

 under the necessity of cancelling their contract at the beginning of the 

 year 1892. These gentlemen continued to handle the work, but as 

 managers, and under the direction of the board. 



The canal. In December, 1889, the Department of Public Works 

 contracted with the Bucyrus Company of the United States, of which 

 Colonel Ellis was the president, for the construction of the canal. 



This company started with two spoon dredgers capable of raising 

 a maximum of 1000 cubic metres, 1308 cubic yards, a day. They 

 commenced operations at the twenty-second kilometre. In the opin- 

 ion of the board of commissioners, the Bucyrus Company was not pro- 

 ceeding with the work at a suitable rate of speed, for at 1000 cubic 

 metres, 1308 cubic yards, per day, the work of dredging alone, as there 

 were some 16,000,000 of cubic metres, 20,928,000 cubic yards, of ex- 

 cavation to do, would take about forty-three years ; their contract was 

 therefore cancelled. 



In May, 1894, the Department of Public Works of Mexico con- 

 tracted with Messrs. S. Pearson & Son of London for the completion 

 of the canal, modifying former contracts of December 25, 1889, March 

 30, 1891, and April 18, 1893, under the following bases: the un- 

 finished excavation in the first nine kilometres, and that between kilo- 

 metre 47 and the entrance of the tunnel of Tequixquiac, are to be 

 continued by the Board of Drainage Directors, who must have the latter 

 portion completed to 10 metres below the surface of the soil by Decem- 

 ber 31, 1894, and to the required depth of the canal by May 31, 1895, 

 in order that the water in the canal may settle to that level and permit 

 the contractors to slope the walls as required by the contract. The 

 contractors are to complete the canal between kilometres 9 and 47 for 

 the sum of $3,506,000. For making the monthly estimates the canal 

 will be divided into two sections kilometres 9 to 22 and kilometres 



