692 EXPERIMENT STATION RECORD. 



.ire that it is difficult to build with a diameter less than 14 ft. and that it has 

 i\n unfinished appearance. 



Four cheap silos, C. I. Bbat and D. R. Foebesteb (Oklahoma 8ta. Circ. 33 

 {1914), pp. 16, figs. 14)- — This circular gives information regarding the con- 

 struction of (1) the homemade 2X6 stave silo, (2) the flooring silo with 

 wooden hoops, (.3) pit silos, and (4) the homemade concrete block silo. 



Lig'htning rods, W. H. Day {Ontario Dept. Agr. Bui. 220 {1914), pp. 88, pi. 

 1, figs. 39). — This bulletin describes and analyzes lightning action and the 

 lightning discharge and stroke with reference to buildings, fences, animals, 

 and human beings. It describes the principles of lightning rods and gives 

 directions for their proper installation on farm buildings. It is concluded from 

 the results of extended investigations " that lightning rods properly installed 

 are almost absolute protection against lightning." 



Domestic refrigeration (Lait. Beige, No. 4 {1914), pp. 31-43, figs. 2). — A 

 description and general data are given concerning small refrigeration plants 

 designed esi)ecially for use in homes and restaurants and in which the refrig- 

 eration is obtained by means of an electrically operated carbon dioxid com- 

 {)ressor. 



A comparative study of circular and rectang'ular Imhoff [sewage] tanks, 

 T. S. JoHNSoif (Bui. 8ci. Lais. Denison Univ., 17 {1914), Art. 9, pp. 341-367, 

 figs. 5). — ^This thesis attempts an economic design of two Imhoff sewage tanks 

 as applied to the disposal plant of a small community and makes comparisons 

 of rectangular and circular tanks with special regard to costs and clarification 

 efficiency. The comparison of cost data only slightly favors the circular tank, 

 and the author concludes " that the advantage of the circular radial-flow type 

 of Imhoff tank over the type known as rectangular-linear flow must lie mainly 

 upon its advantage.** as to clarification efficiency. And here, too, enough ques- 

 tions will arise to make the problem one that can be best solved for each loca- 

 tion or installation." 



A bibliography is appended. 



[Telephony in rural districts] {Electrician [London], 72 {1914), No. 25, pp. 

 1035-1038, figs. 6; abs. in Elect. World, 63 {1914), No. 17, p. 9^7).— This is an 

 illustrated article on the Steidle telephone system in use in Germany. Ther» 

 are used a manual main exchange nnd automatic subexchanges. 



The loose leaf drafting manual, C B. Howe {New York and London, 1913, 

 pp. 82, figs. 146). — A number of exercises in machine and agricultural drafting 

 are given. 



RTJRAL ECONOimCS. 



Depopulation of rural districts, E. Laub (Fiihling's Landw. Ztg., 63 {1914), 

 Nos. 1, pp. 1-22; 2, pp. 53-62). — The author, by a study of the peoples of 

 various countries whose population aggregates over 350,000,000 persons, shows 

 than the urban population is increasing faster than the rural, so that the rural 

 population forms a decreasing proportion of the total. It is only in the older 

 countries, however, thnt there has been an actual decrease in the rural popula- 

 tion. Some of the causes contributing to the migration of people from rural 

 districts are low wages, long hours of work, and the lack of social standing, 

 outlook for the future, amnsement.s, and opportunity for marriage. In many 

 instances there is no provision for old age nor chances for making a large in- 

 come such as are found in the cities. In many cases the influence of the school 

 does not tend to build up the rural community. 



The progress of the small holdings movement {Bd. Agr. and Fisheriee 

 \Lo7idon], Ann. Hpt. Proc. Hmall Hold, nnd Allot. Acts [etc.], 1913. pt. /, pp. 

 58; abs. in Jour. Bd. Agr. [London]. 21 (Un/f). No. 2. pp. 157-159) .—Since th« 



