[17] 



POND CULTURE. 



48; 



and the line HJ the edge of the sole. The spax^e between the front ind 

 back edge EH .s called the sole of the dike, and the entiL sple s 

 called the breadth of the sole. ^ ^ 



As regards the ditches the same rules apply to the proportion of their 

 dimensions and to their scarps as with the 

 dikes, and similar terms are used. The in- 

 clined side of the ditch is called the scarp 

 i and n g. The lines drawn from one bank 



^■, to a point Ic, and from n to m, where (at h 



and m) it meets a vertical line, is called the 



base line of the scarp. The bottom of the 



ditch, o g^ IS called the sole, the boundary 



line between the sole and the sides & o and 



eg are called the edges of the sole, and the 



boundary lines between the sides and the 



banks a * and <Z w are called the edges of 



the bank. The distance, % n, from the* edge 



of one. bank to the other is called the 



breadth of the ditch, and the distance from 



one edge of the sole to the other, o g, the 



bread.«i of the sole. The distance from one 



side to the other over the surface of the 



water, r s, is called the breadth of the water- 

 level. 



A.~Building the diJce and constructing the ditches. 

 BUILDING EARTH-DIKES. 



Before beginning the building of the dike it should be accurately 

 aid out, t. e., along the entire length of the proposed dike, the edge- 

 lines of the crest, & / and o g, and the edge-lines of the sole, a e and 

 a h, are marked by pegs and ropes. 



As soon as this has been done the elevation is marked by poles and 

 boards, (.)(/>), (6) (ft), (.) (,), and (o) (d), first of aU at both ends of the 

 dike, and, if it is not to run in a straight line, at every angle. Be- 

 wf. I"'!.'^/'^'''*' intermediate poles are placed along the proposed 

 lines of the dike at intervals of 2 meters. In placing these intermedi- 

 TJ '" P"'^^,^^ ^°^ «^«"ld begin from the highest points down- 

 ward ; and this rule should invariably be observed, as it will be impos- 

 sible to find a perfect plain for the building of a dike. The scarps of 

 the angles and the intermediate poles are determined by placing the 

 eje close to the poles at one end and taking aim towards the ])oIes at 

 ine other end. In order to insure successful work the poles or boards 

 marking one and the same scarp should all incline at exactly the same 



pDglO. 



