576 



SCIENCE 



[N. S. Vol. XXXVn. No. 954 



The methods in use and proposed for the dis- 

 tillation of tars and refined tars in road work are 

 so varied and give such varied results that there 

 is urgent call for their standardization. Attention 

 is called to the excellent work of the Subcommittee 

 on Distillation of Committee D — i of the Amer- 

 ican Society for Testing Materials and their 

 recommendations.' 



The distillation test in a specification should be 

 so drawn as to show, in conjunction with the free 

 carbon, specific gravity and viscosity: (1) absence 

 of water; (2) character of tars used; (3) method 

 of refining. It is important that in addition to 

 the amount of distillate, its specific gravity and 

 the melting point of the residue be required. 

 Classification of BocTcs Used in the Construction of 

 Boads and Pavements: Charles P. Bebket, 

 assistant professor of geology, Columbia Uni- 

 versity. 

 Read by title. 

 Specifications for Patented Pavements: WHALiM 

 H. CoNNELL, chief, Bureau of Highways and 

 Street Cleaning, Philadelphia. 

 Bead by the secretary. 

 The History of the TopeTca Bituminous Concrete 

 Pavement: Theo. S. DeLay, city engineer, 

 Creston, Iowa. 



In the early days of the use of bituminous 

 paving surfaces various arrangements of aggre- 

 gate and various bituminous materials were used, 

 the materials and methods being adapted to the 

 work contemplated. 



About the year 1893 Marcus A. Hodgman, a 

 paving superintendent, in the employ of P. 0. 

 Blake, in Denver, reverted to some of the earlier 

 practises in laying bituminous pavements. 



Hodgman 's work was seen by Frederick J. 

 Warren, an employee of the Barber Asphalt 

 Paving Company, who subsequently resigned from 

 the employ of that company, went east, and took 

 out a patent on a similar form of construction. 



Warren organized the Warren Brothers Com- 

 pany to promote the invention and by vigorous 

 promotion methods succeeded in having built a 

 very considerable yardage of paving in accordance 

 with this method. 



Hodgman died in 1903, but Blake continued in 

 the paving business and evidently still had a good 

 opinion of Hodgman 's idea, as he promoted some 



^Proceedings of the American Society for Test- 

 ing Materials, Vol. XI., 1911. 



pavement in accordance with that principle in 

 Topeka, Kansas, about the year 1908. 



Before this work was constructed, Warren 

 Brothers Company brought suit for infringement 

 of patent against the city of Topeka and the 

 contractor. The defendants called on Blake for 

 assistance to such good purpose that, when the 

 case came up for trial, the plaintiff was willing 

 to enter an agreed decree waiving claim of 

 infringement but enjoining plaintiff against in- 

 fringing. 



Early in 1910 the city of Creston, Iowa, started 

 proceedings for the construction of 25,000 yards 

 of bituminous concrete paving and adopted the 

 specifications used at Topeka. Creston also was 

 made defendant in a suit by Warren Brothers 

 Company, and this was settled by an agreed decree 

 as in the Topeka case, but without any injunction 

 clause. 



Since it has become knovni that this form of 

 pavement is free of difficulties it has been used 

 very extensively in the middle west, with general 

 satisfaction. It is not, however, a new form of 

 construction, as it has been in continuous use in 

 Pittsburgh, Pa., since 1897. 



Its use has been instrumental in greatly re- 

 ducing the cost of paving to the taxpayer, as may 

 be seen by comparing prices at Creston with those 

 of other places. 



As this form of construction yields no exorbitant 

 profits it has no promoters, hence has not met with 

 acceptance as rapidly as its merits deserve. 



It is subject to one objection common to all 

 continuous pavements, namely, cracking under 

 sudden changes of temperature. These cracks do 

 no harm, show no inclination to ravel, and close 

 up during warm weather when suflicient trafiic 

 passes to keep the pavement worked. 

 Economical Methods of Repairing Sheet Asphalt 



Pavements: H. B. Pullar, assistant manager 



and chief chemist. The American Asphaltum 



and Rubber Co., Chicago. 



Read by title. 



Limitations in the Use of Bituminous Carpet Sur- 

 faces: Arthur W. Dean, chief engineer, Massa- 

 chusetts Highway Commission, Boston. 

 Bead by title. 



The Maintenance of Bituminous Pavements: Jas. 

 C. Travilla, street commissioner, St. Louis. 

 Read by title. 



Observations on Slipperiness of Bituminous Sur- 

 faces and Bituminous Pavements: W. D. Uhlee, 



