RURAL ENGINEERING. 85 



ble wire hoop of No. 7 wire, 0.17G in. in diameter; 2, 3, 4, 5, aud 6 double wire 

 hoops beinj; used. 



The reinforced tile had a lower breaking strength when tested wet than 

 when dry. Tile reinforced with 2 double wire hoops collapsed like plain tile. 

 Three reinforcing hoops increased the strength 28.4 per cent; 4 hoops, 46.2 per 

 cent ; 5 hoops, 88 per cent ; and 6 hoops, 102 per cent. 



Handy tables for computing the cost of tile drains, J. L. Parsons {Hum- 

 boldt, Iowa [WlJf], pp. 20). 



Notes upon the water hyacinth, li. T. Ward {Prof. Mem. Corps Engin. U. 8. 

 Army, 6 {1914), No. 29, pp. 6^-648, fig. i).— Methods of destroying excessive 

 growths of the water hyacinth in waterways and drainage channels are de- 

 scribed, the most successful method being that of spraying with a chemical 

 solution. 



Earth roads, C. E. Morrison {New York, 1914, PP- V+30; rev. in Good Roads, 

 n. ser., 8 {1914), No. 1, p. 26) j — "This book, which is a brief treatise on the 

 elementary principles of the construction of earth roads, is intended primarily 

 for the road officials of small towns, road districts, and the like, and for lay- 

 men in general. The subject-matter, while dealing with the technic of road 

 building, is presented in nontechnical language. Throughout the book the 

 effort has been to secure conciseness and simplicity and, at the same time, 

 present all the salient features of the subject. The text is divided into sec- 

 tions on general considerations, road location, cost as affected by location, 

 traction, grades, soil conditions, drainage, width of roads, side slopes, earth 

 work, maintenance, dragging, sand-clay roads, and burnt-clay roads. The book 

 is illustrated by drawings showing correct and incorrect cross sections for roads 

 on various kinds of soil, underdrainage systems, ditches, and drains; and by a 

 full-page working drawing for a 2-ft. reenforced-concrete box culvert." 



The use of explosives in agriculture, H. F. Macmillan {Dept. Agr. Ceylon 

 Bui. 8 {1913), pp. 105-118, pis. 9). — This bulletin records the results of several 

 tests to determine the radial effect of an explosive in definite but varying con- 

 ditions of soil, and describes recognized methods of procedure in blasting soils, 

 bowlders, and stumps, as well as the necessary precaution to be observed. 



The radial disturbing effect of a one-cartridge charge was noticable at 3 ft. 

 and distinctly evident at 2 ft., but was not visible at 4-ft. distance in ordinary 

 light soil in dry weather. Very similar results were obtaned in a hard gravelly 

 " cabook " soil after heavy rains. In a stiff clayey " cabook " soil the I'adial 

 effect of a one-cartridge charge was visible at distances of 2, 2J, and 3 ft. 



Similar charges were exploded in similar soils and let stand for two months 

 without opening. A hole 2i ft. deep placed between tea bushes showed no 

 traces of collected water when opened in dry weather but was partly filled with 

 loose earth and plant roots. Holes in the " cabook " and gravelly " cabook " 

 soils showed distinct signs of the collection of moisture, although the surround- 

 ing soil was dry. It is concluded that in practical opei^ations of this kind such 

 holes should, after the lapse of a few hours or so, be prodded well through with 

 a crowbar to prevent needless empty spaces; or the holes may be dug up and 

 an application of manure or mulch mixed with the soil. 



The results of stump-blasting tests were not particularly successful owing to 

 the formidable nature of the stumps blasted out, but they indicate the possi- 

 bilities along this line. 



The author arrives at the general conclusion that the effects of blasting on 

 soils are analogous to those of manuring and the benefits more lasting. " Though 

 the eflicieucy of the use of explosives generally leaves little room for doubt, the 

 question of cost will obviously weigh largely with many planters who contem- 

 plate adopting it. The initial outlay, however, should be regarded rather in 



