Vj20i CONTENTS. VII 



* Page. 



'Jlic duty of water in tho Pacific Nortliwest, Sti'vons -TO 



Well waters lor irrijjatioii, Vallejo 1 ^T9 



Water supply hy means of cisterns, Nikolai -T!) 



A suyj^esiion on a method for purifying water, Linliart -7!) 



The action of water on lead, Livi-rseege and Kuapp 279 



Water powers of tlie United States 280 



Engineering for land drainage, Elliott 280 



Studies of maintenance work on drainage ditches, Lynde 280 



Hydraulic-lill dams, Hazen 280 



The record of 100 dam failures, Jorgensen 281 



I'rotection of inclined soils against washing, Caldieri 281 



Control of water on nills, Fronzi 281 



Adapting automobile to soil survey work. Carter et al 281 



Value of connnon rock salt and sulphur for killing live stumps, ltudolfs_ 281 



TNT as a i)lasting explosive, Muuroe and Howell 282 



- Cement in 191S, lUircliard 282 



Pliysical properties of magnesia cement and compounds, lloark 282 



Antiseptic treatment of timber. King 283 



Relation l)etween viscosity and penetrance of creosote in wood, Bateman_ 283 



The protective values of structural steel paints, Coye 283 



Highway classitication undertaken by Bureau Public Roads 284 



Field manual 284 



Reinforced-concrete roads, Walker 284 



Reinforced-concrete road construction, Sliellard 284 



Concrete road work: Special reference to available aggregates, Johnson. 284 



Stresses in concrete roads. — Correct positi()n of reinforcement 284 



Reduction of labor in the computation of vertical curves, Brevid 284 



Can we alTord to delay road improvemeatV Fixmer 284 



Traflic on Iowa highways, Agg 284 



The use of electricity in agriculture, Crowley 285 



Belting for power transmission, Wilson 285 



Motor-truck design and construction, Scliaefer 285 



Relation of solid and pneumatic tires to motor-truck efficiency, Norton — 286 



Tests reveal relative values of pneumatic and solid tires, Masury 286 



Thirteen years of tractor development worlv, McCollough 286 



H<)W they test tractors at Purdue University, Benjamin 287 



The Lincoln [tractor] trials, September, 1919, Tweedy 287 



Mechanical analysis of tractors at K. C. show, Farrington and Herdmau_ 287 



192U tractor and implement blue book 287 



A tractor engine test, Norman and Stocktletli 287 



Tlie problem of good valves for the tractor, Willard 288 



Comparing tractor speeds witli power, Fruddeu 288 



The design of light tractor plows, Bergin 288 



The week of motor cultivation at Senlis, Greilsammer 289 



Mechanical cultivation in 1919, Coupan i 289 



Cultural care of plantations, vines, and groves for silage Opazo G 289 



Farm im|>Unicnts and machinery in France and North Africa Groves 289 



Useful data on reinforced-concrete ))uildings 289 



Attractive design for a country house Adi'ianzeu 289 



Stables, P.ernnien 290 



Measurement of stacks to find w«'ight of contents Macpherson 290 



Scientific methods of sewage disposal Tucker -^ 290 



Sewage disposal in the privatt' home, Miller 290 



RURAL ECONOMICS. 



Rent contracts in typical countries of the wheat belt, Boeger ^ 290 



Agricultural war damages — a guide for their estimation 290 



Cohinization projects, Yamandi 290 



Selecting a farm, Tliomson 291 



[Report of farm management survey work], Leitch and Neale 291 



Dairying turned the trick, McDowell 291 



[Study by Amei-ic.in Association for AizricuKural Legislation!, Cox 291 



(Report of Porto Rico connnissioner of agriculture and labor], Camuiias- 291 



Agrhultural i)roducts [of Brazil], Redtield and Watkius 291 



[Agricultural France] 292 



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