THE IRKIGATION AGE. 



81 



sufficient to admit of a deep waterway a drainage ditch 

 should be from 6 to 12 feet deep and the ditch should 

 not be over 4, 6 or 8 feet in width on the bottom, except 

 where a ditch of unusually large capacity is required. 

 By digging a deep ditch, narrow on the bottom, the 

 velocity of the flow is increased, making the ditch self- 

 cleaning and where land is under-drained a free flow of 

 water is obtained at the mouth of the tile preventing 

 the underdrainage system being choked with silt. 



Rear view of Austin Drainage Excavator, showing perfect slope of banks 

 and wide, clean berms. 



In excavating the ditch it should be done in a 

 manner that will enable it to be made perfectly true to 

 the engineer's specifications, the banks and bottom must 

 be made as firm as it is possible to make them and 

 the waste banks must be constructed at a distance from 

 the ditch that will prevent them being returned through 

 the action of the elements. 



Photograph of a ditch one year o'.d constructed by the Austin Drainage 



Excavator, demonstrating that ditches constructed in this 



manner maintain their original shape and 



become permanent waterways. 



No system of excavating an irregular channel and 

 grading down banks and bottom to the desired slopes 

 can produce a ditch with as firm banks and bottom as 



the solid strata of the earth and it is therefore obvious 

 that if a ditch can be shaved out of the virgin earth and 

 the excavated soil removed to such a distance that it 

 will be prevented from being returned through the 

 action of frost, erosion or wind and banks and bottom 

 left perfectly smooth and true to grade, the best ditch 

 possible to produce in earth construction is obtained. 



Several State engineers have made many specifica- 

 tions for ditches calling for a width of bottom of from 

 8 to 12 feet and a width of berm of only 4 feet and 

 many persons have understood this to be the engineers' 

 recommendation of a perfectly shaped ditch, however, 

 they have invariably acknowledged that these specifica- 

 tions did not produce a ditch of perfect form, but were 

 made to enable them to be constructed by ditching ma- 

 chines, which could not produce a narrower bottom or 

 wider berm. 



It is obvious that where a ditch is excavated with 

 practically vertical banks and a large quantity of the 

 excavated earth is piled immediately adjacent to the 

 ditch that this added weight increases the tendency of 



Ditch 12 feet deep, with 4-foot bottom and l'/ 2 to 1 slope built by the 

 Austin Drainage Excavator in Cass County, Ind., illustrat- 

 ing ditch that is perfectly self-cleaning where 

 there is a variable flow of water. 



banks to cave and it is only a question of a few years 

 at most until a large proportion of the excavated soil 

 will be returned to the waterway. To obtain a perfect 

 ditch the banks must not only be shaved out of the 

 solid strata of the earth to an angle that will prevent 

 tendency to cave, but a berm of from ten to fifteen feet 

 is required to prevent the excavated earth being re- 

 turned to the ditch. 



We are illustrating herewith ditches excavated by 

 dipper dredges and the Austin drainage excavator, 

 showing the machines in operation, the results obtained 

 in the new ditches and other illustrations showing the 

 conditions of ditches made by these different methods- 

 when one to three years old. Two views of the Austin 

 drainage excavator in operation are shown, one a front 

 view illustrating the manner in which this machine 

 propels itself forward or backward by means of a track 

 placed on each side of the ditch enabling it to operate 

 in either direction. The other view, taken from the 

 rear, shows how this machine shaves out a ditch from 

 the solid strata of the earth, slopes the bank to any 



