OFFICE OF PUBLIC ROADS AND RUEAL ENGINEERING. 325 



which passed through this division, or a total increase of 10 per cent 

 over the work of the previous year. This was accomplished without 

 any increase in the working force. A revision of the bulletin on 

 rocks for road building, with considerable new matter, has been 

 prepared for publication. 



During the fiscal year instruction in the work of the chemical and 

 ]:)etrographic laboratories has been given to 1 senior highway engi- 

 neer of the office, 7 civil engineer students, and 3 representatives from 

 State universities or technical schools. 



FIELD EXPERIMENTS. 



E. B. McCoRMicK, Mechanical Etiffineer. 



Traction tests have been continued. The object of these tests is to 

 determine the actual eilect of road improvement on draft, and also 

 the eifect of width of tire, of diameter of wheels, and of method of 

 hitching on draft. Final tests have been completed on projects in 

 Iowa (Ames), Maryland, and Alabama. Preliminary tests have been 

 made on projects in Iowa (Dubuque), Texas, South Carolina, North 

 Carolina, and Virginia (Arlington). These projects range from 5 to 

 75 miles in length, and reports are in process of compilation on the 

 projects in Iowa (Ames), Alabama, and Maryland. 



In the securing of information in regard to the effect of different 

 types and conditions of road surfaces on the draft of self-propelled 

 vehicles, no commercial type of dynamometer has been found satis- 

 factory for this work, and the office has found it necessary to design 

 and construct one to fulfill its own particular conditions. This has 

 been done and the dynamometer is being tried out experimentally. 



DIVISION^ ADDED UNDER REORGANIZATION. 



DRAINAGE INVESTIGATIONS. 



S. H. McCeory, Chief. 



Since April 1, 1915, a gradual rearrangement has been made in ad- 

 ministrative details, to fit the drainage work to the organization of 

 the Office of Public Eoads and Rural Engineering and to coordinate 

 it with the work of the other divisions. 



The work of drainage investigations for this year is reported by 

 the Director of the Office of Experiment Stations. The principal 

 investigations since April 1 include the examination of peat and 

 muck lands in Florida and in States north of the Ohio River; a 

 survey of the overflowed lands on Panther Creek, in Daviess County, 

 Ky. ; and the gaugings of the Kootenai River in northern Idaho to 

 estimate the rate of flood flow that must be accommodated by drain- 

 age improvements to reclaim the overflowed lands along that river. 

 The installation of a pumping plant and other equipment has been 

 made on the Arlington Experiment Farm, Virginia, to determine by 

 laboratory methods the carrying capacity of drains having various 

 rates of fall. Plans have been made for a careful study of 

 the laws and regulations governing the organization of drainage 

 districts; the methods of financing such organizations, particularly 

 the requirements for making drainage bonds readily salable; and 

 the laws governing the rights of drainage districts and other indi- 



