ROADS AND BRIDGES 349 



inches deep and filling with gravel or cinders, using fine 

 gravel for the surface. (3) If the soil is sandy, clay 

 may be mixed with the sand and a thin layer of fine 

 gravel used on top. Placing this walk or path on the 

 grade is not usually practical, because teams will dis- 

 turb it unless it is protected by the ditch bank. 



Lumbermen's ice roads are an important feature of 

 modern lumbering operations in cold regions. In north- 

 ern Minnesota, for instance, the lumbermen cut out a 

 road from the woods where the trees are felled to the 

 local sawmill or to the lake or river where the logs are 

 to enter the water to be floated to their destination, or 

 to the side of the railway 

 which is to carry them to 

 the lumber mills. These 

 roadways are cleared out 

 and made fairly level before 



J Figure 238. ,~~ 



the SOU IS frozen, Or if not wheel track and ditch. 



made until freezing, they are 



leveled up by means of snow. Water is then hauled in 

 large tanks and used to sprinkle the surface of the 

 runner track, making it solid ice. These roads are made 

 sufficiently wide so that the horses walk inside the 



grooves where the sled 

 runners glide on smooth 

 ice. By occasionally going 

 over these roads during the 

 winter with the sprinkling 



Figure 239. Cross-section of a ford across , i r 



a creek. Ordinary water level in a stream tank, a SUrtaCC OI SmOOttt 



shown. The dotted lines represent ford . . . . j 



graded down and surfaced with stone. In ICC IS maintained OVCr 

 many instances the bed of the stream is ., . , , . , 



solid and the stone surfacing is necessary which the horSCS With 

 only at the outer edge of the water, as at 



R-A or X-Y. sharp shoes can draw im- 



mense loads of logs at comparatively very small expense 

 per thousand feet. 



Fords. Fords are a necessity in pioneer communities, 

 and often remain permanently, both in public highways 



