1920] RURAL ENGINEERING. 485 



The tractor was easy to drive and maneuver, but could not work In the rice 

 Oolds as it sunk too deeply into tlie soft soil. As a result of three months'- 

 experiments it is recomniendetl that the chain tracks be widened from 27.3 

 in. to fronr 33 to 35 in. and fitted with strakes projecting about 3 in. at right 

 angles to the tracks to prevent slipping. The tractor should also be supplied 

 with a carbureter to enable it to burn iiaraflin, an electric lighting apparatus 

 lc> permit night work, and a special pulley for driving farm machinery. It 

 is noted that the hitch point between the tractor and plows was too low, 

 cruising the first two shares to work -too deeply. 



The plows were unsuitable for rice field work, the shares being too close 

 together longitudinally ami too large and heavy. The system of lifting with 

 levers and toothed sectors should be replaced by a system with a wheel and 

 vertical endless screw. The shares should be at least 35 in. apart in hori- 

 zontal alignment. The trailing wheels should be replaced by very large and 

 very light drums. 



Retaining walls — their design and construction, G. Paaswell {New Yorh 

 and London: McV.ntw-Hill Book Co., Inc., pp. X+275, pis. 9, figs. 135).— ThQ 

 first chapter of this book presents the existing theories of lateral earth pressure 

 and attempts to codify such theories, evolving a simple but well founded ex- 

 pression for the thrust. In following chapters it is attempted to continue this 

 codification throughout the theories of retaining-wall design so that a direct 

 and c(tntinuofis analysis may be made of a wall from the preliminary selection 

 of the type to the finished section. 



Part 2 of this book deals with construction, including a full presentation of 

 the modern development of concreting, with frequent extracts from some of 

 the recent important reports of laboratory investigators. A feature of this 

 section is data on the principles of proper construction plant selection. 

 • A final section contains specifications and an extensive bibliography. 



Securing a dry cellar, G. M. Warren (U. S. Dept. Agr. Yearbook 1919, ^p. 

 425-4Jt9, figs. 2i).— Practical information is given on the damp-proofing of 

 cellars and cellar walls, both, during and after construction. 



Silo construction, C. K. Shedd and W. A. Foster (Dir. Jen. Serv. Agr. 

 [Chile] Bol. 50 (19J9), pp. 66, figs. >}5). — This material has been previously 

 noted as Bulletin 189 of the Iowa Station (E. S. R., 41, p. 691). 



Practical hog houses for Indiana, C. A. Norman and J. W. Schwab (Pur- 

 due Agr. E.i't. Bui. 16, rev. ed., (1920), pp. 8, figs. 13). — This is a revised edition 

 of this bulletin, previously noted (E. S. R., 41, p. 58G). 



How to make and use a self-feeder for hogs, J. W. Schwab and O. A. 

 Nokman (Purdue Agr. Ext. Bui. 90 (1920), pp. 8, figs. 4).— A hog self-feefler 

 found to be suitable for Indiana conditions is described and illustrated, and 

 a bill of materials is included. 'The outstanding features of this design are (1) 

 vertical sides, insuring the contents feeding down properly, (2) covered 

 troughs, which keep out chickens and weather, (3) divider boards inside the 

 feeder, set at a 45° angle and extending out into the troughs a little past the 

 side wall of the feeder, (4) one side of tlie roof and the comb boards nailed 

 securely with the other side in two sections, and (5) an adjustable feed opening. 



How to build a self-feeder for liogs, C. I'. Thompson (Kans. Agr. Col. Ext. 

 X Form No. 2ff (1918), pp. [2], figs. 3). — Photographs and drawings of a self- 

 feeder for hogs are given. 



Self-feeders for hogs, G. Bohstedt (Chester White Jour., 10 (1920), No. 

 12, pp. 18-20, figs. 8). — Self-feeders for hogs adapted to Wisconsin conditions 

 are desa-ibed and detailed drawings and bills of material included. 



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