IRRIGATION TOOLS AND DEVICES 



441 



vators. The main thing is to fit the tool to the crop and 

 the soil. Particularly important is the soil. Most harrows 

 and cultivators are now so built that different kinds of 

 teeth and shovels may be attached; thereby a much larger 

 field of service is possible. (Figs. 157-161.) 



258. Measuring the flow of water. Brief consider- 

 ation of this subject has been given hi Chapter XVII. 



FIG. 165. Current meters. 



Special engineering treatises should be consulted for more 

 information. All in all, some form of the weir is the best 

 measuring device on the farm. It often becomes desirable 

 for the farmer to keep a constant record of the water 

 flowing over a weir. To do this, automatic registers con- 

 nected with floats, and run by clockwork, have been 

 devised. The rising and falling of the float, indicating the 



