186 EXPERIMENT STATION EECORD. 



sizes in close contact, but witliout bond, the cohesion between the several pieces 

 having been broken by microscopical hair-cracks, formed by shrinkage. . . . 

 These natural lines of cleavage form lines of weakness, along which the con- 

 crete is easily fractured by external force, which ordinarily would not cause 

 sufficient stress to overcome the cohesion of a solid concrete slab." 



Approximate stresses produced by a concentrated load on a continuous 

 slab supported on earth or other yielding foundation, J. W. Pearl (Engin. 

 and Contract., J,l (IDUf), Ko. 6, pp. 186-188, figs. 3).— The author derives for- 

 mulas with diagrams to determine the stress produced by a concentrated load 

 on concrete pavement slabs supported on earth or other yielding foundation. 

 He discusses the formulas and illustrates their application to pavements and to 

 flat concrete slabs on columns. 



Strength of large pipes, D. R. Cooper and E. R. Weinmann (Engin. Rec, 

 C!i (WlJf), No. 5, pp. 133-137, figs. 16). — This is a mathematical discussion of 

 stresses in circular conduits, with or without internal pressure, and with various 

 widths of support at bottom. 



Reinforced concrete construction, G. A. Hool CSew York and London, 1912, 

 vol. 1, pp. X+25Jf, figs. 88; 1913, vol. 2, pp. 659).— The first volume of this work 

 deals with the fundamental principles of reinforced concrete design and includes 

 numerous tables and diagrams to facilitate the calculation and designs of re- 

 inforced concrete structures. The work "presupposes a knowledge of the ele- 

 ments of structures." The chapters included are as follows : Concrete ; steel ; 

 concrete and steel in combination; rectangular beams; slabs, cross-beams, and 

 girders; columns; slab, beam, and column tables; slab, beam, and column dia- 

 grams ; and bending and direct stress. 



Volume 2 covers in some detail the subjects of retaining walls and buildings. 

 The first part is subdivided into chapters on theory of stability, design, and con- 

 struction of retaining walls. The second part deals with buildings, the first sec- 

 tion including chapters on floors, types of reinforcement, roofs, columns, 

 foundations, walls and partitions, stairs, contraction and expansion, shear and 

 moment considerations in continuous beams, eccentric load consideration in col- 

 umns, and wind stresses. The second section contains chapters on materials,' 

 forms, bending and placing of reinforcement, proportioning, mixing, and placing 

 of concrete, finishing concrete surfaces, and waterproofing of concrete. The 

 third section covers estimating unit costs, estimating quantities, and an example 

 of an estimate for a concrete building. 



[Farm power and machinery] (Prairie Farmer, 86 (1914), No. 3, pp. 12S, 

 figs. 8). — Special articles on farm power are included as follows: Tractor v. 

 Horse as a Source of Farm Power, by H. J. Sconce (pp. 81, 82) ; Shall I Buy a 

 Farm Tractor? by I. W. Dickerson (p. 82) ; [The AVork of the Gas Engine], by 

 F. M. White (pp. 83, 95) ; Points on the Purchase and Care of Farm Machinery, 

 by C. O. Reed (pp. 83, 84, 96) ; The Windmill as a Source of Power on the 

 Farm, by E. A. White (pp. 85, 96, 97) ; [Household Power Conveniences], by 

 L. W. Chase (pp. 87, 105, 106) ; and [Farm Machinery Review for 1914], by 

 F. M. White (pp. 85-87, 100, 101, 103, 106, 107, 111, 119). 



Farm motors, A. A. Potter (New York and London, 1913, pp. IX+261, figs. 

 278). — This book is intended to include the fundamental principles governing 

 the construction, working, and management of motors which are suitable for 

 farm use, including steam engines, gas, and oil engines, traction engines, auto- 

 mobiles, water motors, windmills, and electric motors. The method followed 

 in each chapter is to give (1) the fundamental principles underlying the par- 

 ticular motor, (2) the principal parts of the motor, (3) the auxiliary parts, 

 (4) the uses to which the particular type of motor is adapted, and (5) the 

 selection, erection, and management of the different machines. Practical 



