686 



EXPERIMENT STATION EECORD. 



The care of dry batteries (Farm Machinery, 1912, No. 1066, p. 26). — This 

 article conmients briefly on the care that should be taken to prevent short cir- 

 cuits and bad connections in dry batteries, and points out the necessity of keep- 

 ing the coil in good condition and the switch and commutator points clean iu 

 order to set the best service from engines that operate from the dry cell. 



Making the '' tractioneer," I.. W. Ellis (Sci. Amer., 106 {1912), No. 6, pp. 

 126-128, figs. 8). — Attention is called to the rapidly increasing demand for men 

 skilled in the operation, care, and upkeep of steam and gas tractors for agri- 

 cultural purposes, men who have a combination of common sense, average en- 

 gineering skill, some farm experience, and good executive ability. It is noted 

 that short courses of instruction along these lines are being introduced into the 

 agricultural colleges and that tractor manufacturing companies are conducting 

 schools for the same purpose in their factories. 



The econoinics of silo construction of permanent materials (concrete and 

 clay tile); construction methods and costs, M. L. King (Enrjin. and Contract., 

 37 (1912), No. 10, pp. 256, 257, figs. 2). — In view of the increasing demand for 

 silos the author discusses the economic advantages of building them of perma- 

 nent materials. A brief outline of the essentials in the materials and details of 

 construction of masonry silos is also given. 



Silage and concrete silos {Wyo. Farm Bui., 1 (1911), No. 5, pp. 69-72, 

 figs. 2). — This article discusses the use of silage and the need for solid-wall 

 silos, and gives a table for use in deciding on the size of silo. Essential details 

 for the location, foundation, and general construction of reenforced concrete 

 silos are given with a bill of materials and costs. 



Parm equipment: Buildings and machinery, P. McConnell (London and 

 "New York, 1910, pp. XV +108, pi. 1, flys. i//).— This handbook of information 

 for the farmer deals principally with the methods of laying out the farm and 

 its homestead, the design and construction of farm buildings and their appur- 

 tenances, sanitation and drainage, farm machinery, and the different types of 

 farm motors. 



RURAL ECONOMICS. 



Tenancy in the North Central States, B. H. Hibbard (Quart. Jour. Econ., 

 25 (1911), No. -'i, pp. 710-729, flys. 2). — This article presents a discussion of 

 many phases of the tenancy problem in the North Central States, showing that 

 tenancy is not a constant and uniform factor throughout the United States, 

 but varies according to geographical divisions and local influences. 



A close parallelism is noted between the value of land per acre and the 

 percentage of tenancy, as shown in the following table prepared from data 

 reported in the thirteenth census: 



Value of land and percentage of tenancy. 



A comparison of groups of counties within a State brings out this relation- 

 ship even more closely. It is further noted that there is a corresponding rela- 



