34 EXPEKIMENT STATION KECOED. [Tol. 35 



might be reduced still lower. ... As to the effect of cold weather, the ex- 

 periments on two-hour and one-and-a-half-hour aeration covered the coldest 

 part of the year, and during this time the lowest recorded temperature of crude 

 sewage treated was 51° F. . . . The best results obtained were when work- 

 ing with from 20 to 25 per cent of sludge, the excess being usually pumped to 

 the drying area from the first and second settling tanks twice a week. From 

 the comparatively small effect of the sterilizing trade wastes it is concluded 

 that ' the influence of sterilizing substances which play such havoc with bacteria 

 beds generally can readily be overcome.' " 



A new method of land clearing, H. D. Scudder {Oreg. Countryman, 8 

 {1916), No. 4, pp. 259-266, figs. 7 ) .— iTsperiments with a newly developed stump 

 burning method are reported. 



The outfit required consists of two heavy cast-iron pieces, namely, the fur- 

 nace and the hood. The furnace is so placed against the unbanked portion of 

 the stump as to direct the fire toward its center the long way through and is 

 then banked. A stovepipe is placed in the top of the furnace and a draft pipe 

 from 10 to 12 ft. long into the front. A blast of flame is thereby driven against 

 the heart of the stump, and, after burning through, the furnace is removed and 

 the hood, fitted with the chimney, put in its place and charpitting continued 

 until the stump is destroyed. 



The tests so far show that the time the stump burner outfit is required aver- 

 ages about one day for each foot diameter of stump. The tests indicate that the 

 cost will vary from 50 to 80 cts. per stump if all the labor is hired. 



Proceedings of the eleventh annual convention of the American BrOad 

 Builders' Association, 1914 {Proc. Atner. Road Builders' Assoc, 11 (1914), PP- 

 SOI, pi. 1, figs. 10). — These proceedings include the following special papers: 



Road and Pavement Dimensions — Widths, Depths, and Crown, by L. White; 

 Koad Foundations — Concrete, Telford, Gravel, etc., by J. A. Johnston ; Organi- 

 zation of a State Highway Department, by J. N. Carlisle; Traffic — Present 

 Tendencies, Probable Development, and Regulation, by A. W. Dean ; Machinery 

 for Construction and Maintenance — State, Municipal, Contractors, Traction 

 Haulage of Stone, Care of Machinery — Instructions to Engineer and Operator, 

 by T. R. Agg ; Brick Roads and Streets, by J. Laylin ; Surfaces or Floors for 

 Bridges, by C. Older; Bituminous Construction and Maintenance — Recent 

 Practice, by W. D. Uhler ; Concrete Roads, by H. J. Kuelling ; Recent Practice 

 in Construction in Wood and Granite Block, by W. A. Howell ; Present Practice 

 in Earth and Gravel Road Construction and Maintenance, by I. O. Baker; 

 Street Paving in Small Cities, by T. H. MacDonald ; Convict Labor in Road 

 Construction, by T. J. Ehrhart ; and Dust Prevention and Street Cleaning, bv 

 W. H. Connell. " 



Relation of mineral composition and rock structure to the physical prop- 

 erties of road materials, E. C. E. Lokd {U. S. Dept. Agr. Bui. 3J^ {1916), pp. 

 26, pis. 8, figs. 3). — In this bulletin a mici'oscopic method of rock analysis by 

 means of a cross-line grating is reviewed and the average mineral composi- 

 tion and physical properties of all rocks analyzed and tested in the Office of 

 Public Roads and Rural Engineering up to January 1, 1914, are given ifi tabu- 

 lar form. "This material has been classified according to composition and 

 structure and the rock-forming constituents have been discussed under the 

 groups of primary and secondary minerals with a view to explaining their 

 essential physical characteristics. The physical properties of rocks for road 

 making and the method of testing this material have also been given and the 

 results obtained used to show, first, in a general way, the relation between these 

 properties and the mineral composition and structure of rocks ; and, secondly, 

 to pomt out mure specifically the effects of secondary compounds upon them." 



