936 EXPERIMENT STATION RECORD. 



"The force required to start a load on the dirt road was about one-fourth the 

 gross load, or not greatly in excess of the upper limit of the tractive force when the 

 wagon was in motion. . . . 



"During these experiments a team of small mules readily drew 12 bales of cotton' 

 on a heavy wagon up the 10 per cent grade of the macadam road, the tractometer 

 indicating a pull of 1,000 lbs. The same team was stalled completely in going down 

 the G per cent grade of the sand road, after pulling the indicator to 1,900 lbs. Nine 

 bales of cotton were removed before the load could be again gotten in motion. The 

 driver refused to venture at all upon the dirt road witli the 12-bale load. 



"Wide tires and narrow tires. — There was also a test luade to demonstrate the prac- 

 tical advantages of wide tires over narrow tires. A piece of clay road was made 

 thoroughly wet. Over one i)ortion of the mud road thus formed a heavily loaded 

 wao-on with 2-inch tires Avas repeatedly drawn. Over the other portion a wide-tired 

 wa'1-on, whose gross load was made etiuivalent to that of the first, was hauled an 

 equal number of times. The tires of the latter wagon were 4 and 5 in. wide and 

 the front axle was shorter than the rear, so that the wheels did not run in the same 

 track. The result was very satisfactory. That part of the road which the narrow- 

 tired wagon traversed was cut and rutted to the depth of several inches, while the 

 remainder was rolled by the wide tires into a smooth surface. Afterwards the tract- 

 ometer was brought upon this road and it was found that twice as much pull was 

 necessary to draw the same load over that half of the road which had been subjected 

 to narrow tires as over the other half.'' 



The results with the tractograph iudicate that — ^ 



"the draft on a dirt road is about 2i times as much as that on a macadam road, 

 and this when conditions are most favorable to the former, namely, when it is pi^r- 

 fectly dry and smooth; . . . that it retiuired nearlj'^ 7 times as much eti'ort to draw 

 the load up the 10 per cent grade as along the level roadway; . . . and that with 

 a team going at au ordinary waliving pace the tractive force on an old asphalt 

 pavement is 2() lbs. ; the tractive force on a good macadam pavement is 38 lbs., and 

 the tractive force on a good dirt road is 96 lbs." 



Data obtained in similar tests by florin and McNeill are given in an 

 appendix. 



Hillside terraces or ditches, F.E.Emery (North Carolina Sta. Ept. 1S95, pp. 

 S19-SJ6, p?s. .', Jigs. 4).— A reprint of Bulletin 121 of the station (E. S. R., 8, p. 91). 



Progress of road construction in the United States ( U. S. Dept. Agr., Office of 

 Road Inquiry Bui. 19, pp. 47). — This is a condensed report of the proceedings of the 

 National Road Parliament held at Atlanta, Georgia, October 17-19, 1895. Besides 

 an address of welcome, address of the president, R. Stone, and "miscellaneous 

 remarks," this bulletin gives reports on road making from the following States: 

 Alabama, Arkansas, California, Connecticut, Florida, Georgia, Illinois, Louisi- 

 ana, :Maine, Massachusetts, Michigan, Mississippi, New Jersey, New York, North 

 Dakota, Ohio, Pennsylvania, Rhode Island, South Carolina, Tennessee, Vermont, 

 and Virginia. 



STATISTICS. 



Agricultural products imported and exported by the United States in the 

 years ended June 30, 1892 to 1896, inclusive ( T. S. Dept. Agr., Section of Foreign 

 Markets Circ. 11, pp. S). 



Sources of the principal agricultural imports of the United States during 

 the five years ended June 30, 1896 ( U. S. Dept. Agr., Section of Foreign Markets 

 Circ. 13, pp. 24). 



'A bale of cotton weighs about 500 lbs. 



