REPORT OF THE SECRETARY. 151 



EXHIBITS AKD ROAD-IMPROVEMENT TRAINS. 



Another important feature of the educational work of the office 

 during the year was the road exhibits displayed at Knoxville, Tenn., 

 during the Appalachian Exposition, and also at Chicago, 111,, during 

 the National Land and Irrigation Exposition. These exhibits at- 

 tracted so much attention at these expositions that various railroad 

 companies applied to the office for the privilege of installing them on 

 cars where they could be shown at the principal towns along their 

 lines. An arrangement was accordingly made with the Pennsylvania 

 Railroad, the State Highway Department of Pennsylvania, and the 

 Pennsylvania State College to cooperate with the office in operating a 

 road-improvement train throughout the State of Pennsylvania. The 

 train carried an exhibit car, which contained not only the models 

 referred to above, but also a large number of enlarged photographs 

 and pictures illustrating various features of the road subject, together 

 with a lecture car, in which illustrated lectures were given at each 

 stopping place. Two other cars were provided with exhibits of mod- 

 ern road-building machinery. Another similar train was started 

 May 1, 1911, over the lines of the Southern Railway. The success 

 of this project is shown by the fact that during the year approxi- 

 mately 65,000 people attended the lectures and viewed the exhibits. 

 This work will be continued along similar lines during the coming 

 year. 



OIL-MIXED CEMENT CONCRETE. 



A very important discovery, that of oil-mixed cement concrete, 

 was made during the fiscal year 1910. Laboratory and service in- 

 vestigations show that the Portland cement concrete of ever3'^day 

 use may be rendered waterproof at very slight extra cost simply by 

 the addition of residual mineral oil. The possibilities for an in- 

 creased and more efficient usefulness of concrete by the application 

 of this method of damp-proofing are manifestly numerous. 



A public patent, which has aroused much interest throughout the 

 country, has been granted to Mr. L. W. Page, Director of the Office 

 of Public Roads, for mixing oil with Portland cement concrete and 

 hydraulic cements giving an alkaline reaction, so that anyone may 

 use this process without the payment of royalties. 



