150 EXPERIMENTS IN ROAD SURFACING 



larger than one and one half inches largest dimension, and 

 from ten to fifteen per cent, of sand. This sand was screened 

 out for section one. 



The Lee gravel is a material similar to the above except 

 that a considerable portion of the bank w^here it is obtained 

 contains a much coarser article and this kind was used exclu- 

 sively. Perhaps three fourths of this gravel consists of smooth 

 water-worn stones, from one to four inches in largest dimen- 

 sion. It contains much less fine sand than the Chesley 

 gravel and was used upon sections 3, 7, 8b, and 9. It was 

 screened and sorted for section 8b into three qualities ; for the 

 bottom layer one and one half inches and larger ; for the 

 middle one, one half inch to one and one half inches, and 

 finer for the binder layer. A little clay was added to the 

 binder layer to make it more adhesive. 



The gravel for section 9 was screened only once, separating 

 the above material into coarse and fine, about on the one inch 

 line. 



The screened gravel of section 7 was freed from fine sand 

 by a screen of about one-fourth inch mesh. 



The reservoir gravel which was employed upon sections 4, 

 5, and 15, is finer than the Chesley in structure. It contains 

 very few stones larger than one inch largest dimension, and 

 has as small a proportion of sand as the Lee gravel. It has a 

 small admixture of clay which gives it, with one exception, 

 the best binding quality of any material used. As employed 

 on sections 4 and 15, the small quantity of sand it possessed 

 was screened out. 



The coarse reservoir sand used on sections 6a and 6b was 

 taken from a difierent portion of the same bank from that 

 above, was of much finer texture, and contained no clay. 

 Probably three fourths of the whole was a sharp plastering 

 sand, the remainder consisting of small pebbles of the nature 

 of that used on sections 4, 5, and 15 as above. 



The coarse sand of section 8a and the Point gravel of sec- 

 tion II were of substantiall} the same composition as the fore- 

 going. 



The E. Emerson gravel, as employed upon sections 13 and 

 14, is similar to that already described, resembling most the 



