1918 J RURAL ECONOMICS. 593 



county is able to levy a sufficient tax to improve all of the roads required in a 

 reasonable len;|tli of time without imposing too great a burden on tl'.e taxpayers, 

 it should by all means adopt this course. The only defense that can be offered 

 for a local bond issue rests upon the common sense principles of payment by 

 installment and of capitalizing undeveloped resources. If a system of roads 

 is to be built, it is usually of common advantage that the people who may be 

 called upon to pay the bills should be permitted to distribute their contributions 

 over a period of years and that all who share in the benefits should also share 

 in the burdens." 



" On January 1, 1915, the total local road and bridge bonds outstanding in 

 the United States, exclusive of cities, amounted to approximately $230,000,000. 

 It is estimated that at least $160,000,000 of these bonds were of the sinking-fund 

 variety ; that the average term was 25 years ; and tliat the average rate of 

 interest was 5 per cent. If these bonds had been issued as serials, for the same 

 term and bearing the same rate of interest, it would have resulted in a total 

 saving of approximately .$42,000,000, or an average annual saving of $1,680,000." 



Tests of concrete road ag-gregates, J. P. Nash {Good Roads, n. ser., H 

 (1917), No. 9, pp. 107-110. lU, fig. i).— Tests made at the University of 

 Texas to determine the resistance to abrasion and the tensile strength of con- 

 crete made from various aggregates are reported. In the tests the chief varia- 

 ble was the coarse aggregate. 



It is pointed out that " the two most important essentials for a satisfactory 

 road are (1) uniformity of wear and (2) a minimum of wear. Whenever 

 these two are combined with a high tensile strength the most satisfactory con- 

 crete road is found. The conclusions drawn from these tests are as follows : 



" The uniformity of wear is obtained when the mortar and the coarse aggre- 

 gate wear equally, such as when crushed limestone or limestone gravel is used. 

 The coarse aggregate should be limited in size to about 1.5 in. When hard, 

 tough stone is used the size should be limited to about 1 in. and the cement 

 content increased. It is questionable if a richer mix than a 1:2:4 is an 

 economical one to use with crushed limestone of the ordinary hardness. Crushed 

 slag when hard and uniform should be satisfactory as a concrete road aggre- 

 gate. In a 1:2:4 concrete, a gravel composed of very hard stone such as 

 flint, or quartz, does not wear uniformly. The action of the cubical shot on 

 the test specimens is a trifle more severe than the traffic on the road. It can 

 not be said that either the crushed stone or gravel tested Is superior as an 

 aggregate to produce concrete having a higher tensile strength," 



An analysis of poppet valve motion, L. T. Knocke (Gas Engine, 19 (1917), 

 No. 9, pp. 436-440, figs. 6). — This is a mathematical analysis of valve mecha- 

 nism for gas engines. 



A new feed rack for winter feeding, H. C. Gardiner ([Bien.] Rpt. Mont. 

 Live Stock Sanif. Bd., 1915-16, pp. 17, 18, pi. 1). — A cattle feeding rack and 

 sheep feeding rack designed for Montana conditions are described and diagram- 

 matically illustrated. 



Poultry house equipment, A. G. Philips and L. L. Jones (Purdue Univ., 

 Dept. Agr. Ext. Bui. 57 (1917), pp. 12, figs. 9).— Nests, feed hoppers, and water- 

 ing vessels are described and diagrammatically illustrated. 



RURAL ECONOMICS. 



The farm-labor problem, D. F. Houston (Washington, D. C: U. 8. Dept. Agr. 

 [1917], pp. 4).— This pamphlet calls attention in a general way to the farm- 

 labor problems, and indicates that the most promising solutions are, first, a 

 systematic survey of the farm-labor situation in order to ascertain the possible 



