278 Statistical Iftotes on Aegico* 



22 to 47. In the first section the provisional estimate will be 40 cents 

 per cubic metre; in the second a sum equal to the quotient obtained 

 by dividing the remainder of the money by the number of cubic metres 

 to be removed. The contractors may suspend the work of the dredgers 

 when they fall below 40 cubic metres per hour, and can proceed with 

 the excavation in any way they wish. The excavation had to be com- 

 pleted by May i, 1896, except in the parts where the dredgers cannot 

 work. Then for each day's delay the contractors must pay $500 fine, 

 and after five months the contract will be rescinded. 



These contractors carried out the work of the canal in two different 

 ways by hand work with centrifugal pumps to draw off the water 

 which filtered into the work, and by means of enormously powerful 

 Couloir dredgers which have a capacity for 3000 cubic metres of ex- 

 cavation per day, and which throw the excavated earth to a distance 

 of more than 200 metres from the centre of the canal. They had five 

 of these dredgers at work, and by means of them excavated to a depth 

 of 20 metres or 65 feet, raising the earth to an elevation of more than 

 1 6 metres, 52^ feet, so as to empty it into the shoots, along which it was 

 carried by a stream of water that delivered it at a considerable dis- 

 tance from the dredger. The dredgers have now done their work, and 

 they have been taken to pieces, packed and transferred to the harbor 

 works at Veracruz. The portion of the canal contracted for was 

 completed to the satisfaction of all concerned in six years. 



The level of the bottom of the canal above the datum line adopted 

 is 2.25 metres, or 7 feet 4 inches, and the mouth of the tunnel is 9.20 

 metres, or 30 feet J inch below the same datum, supposed to pass 10 

 metres, or 33.80 feet below the bottom of the Aztec calendar stone, since 

 transferred to the National Museum. The level of the ground at the 

 beginning of the canal is 8.94 metres, or 29 feet 4 inches, and at the 

 end 15.86 metres, or 52 feet above datum. The uniform slope of the 

 canal is at the rate of 0.187 P er kilometre. 



The canal has a depth, at its commencement, of 5.50 metres, or 18 

 feet, which in the last few kilometres is increased to 20.50 metres, or 67 

 feet 3 inches. The side slopes were projected with a batter of 45 de- 

 grees, and the width of the bottom is 5.50 metres, or 18 feet for the first 

 20 kilometres, or I2-J miles, and 6.50 metres or 21 feet 2 inches in the rest 

 of the canal. The first 20 kilometres, or 12% miles, may be considered 

 as a prolongation of the net of sewers in the city, and will receive only 

 the water that passes through them. The flow is calculated for an 

 average of 5 cubic metres, or 176^ cubic feet, although, when heavy 

 rains require it, they can receive a greater volume; the rest of the 

 canal communicates with Lake Texcoco, and will be utilized in con- 

 trolling its waters, the lowest in the valley, which can be made to 

 flow into the canal from all parts. Hence the canal has been built to 



