1917] 



RURAL ENGINEERING. 387 



Struts, Including laminated members, timber-tension members, tension rods, 

 and bracing trusses. Part 7 discusses the complete design of timber trusses, 

 both of the simple and lattice type. Part 8 deals with timber columns, col- 

 umn connections, and joist hangers. The use of mill construction for reducing 

 the fire risk in timber structures is also considered. Part 9 deals with timber 

 foundations, including anchorages for columns. Part 10 discusses miscel- 

 laneous structures. Including flumes, head frames, and tank towers, and also 

 considers wind stresses and the preparation of working drawings. General 

 specifications for timber buildings of the mill-building type are also given. 



Elementary primer of electricity for light and power customers (Salem, 

 Oreg.: Univ. Oreg., 1916, pp. 95, pi. 1, figs. 8).— This bulletin gives general In- 

 formation for the nontechnical reader regarding electricity and its use, and 

 deals in some detail with the use of electricity in the home and on the farm, 

 with special reference to Oregon conditions. A final section deals with the 

 relation of the hydroelectric power resources to the prospective industrial 

 development of Oregon. 



Performance of two successful windmill generating plants, F. S. Culver 

 {Elect. World, 69 (1917), No. 8, pp. 367-369, figs. 7).— This article states the 

 considerations on which the selection of the equipment for the two plants was 

 based, describes features of the arrangements employed, and gives the results 

 of tests of the plants showing their ability to utilize a wide range of wind 

 velocities. 



The results of tests of the chain-driven and geared types of plant showed 

 " that with a wind velocity of 22 miles per hour the charging rate of the geared 

 plant had nearly reached a maximum, while with the chain-driven plant the 

 charging current was increasing almost directly wi'^i the wind velocity. This 

 action is due to the difference in adjustment of the differential windings of 

 the generators. In the first case nearly the entire winding was effective, while 

 in the other it was nearly all cut out of circuit. Thus, by adjusting the amount 

 of the differential winding in circuit the peak charging current can be easily 

 controlled. Another interesting fact is the low wind velocity at which the 

 generator will charge the storage battery, current being furnished with a wind 

 velocity of only 10 miles per hour." 



Electric heating, E. A. Wilcox (San Francisco: Technical Publishing Co., 

 1916, pp. [V/]-f286. figs. 192). — This is a semitechnical presentation of the 

 different uses of electric heat, in which the advantages and disadvantnges of 

 various kinds of heating loads are compared and several types of heating de- 

 vices explained. Data are given on the relative operating costs of electric and 

 fuel-heiited apparatus, together with suggestions regarding approved methods 

 of installing and using domestic and commercial ranges, bake ovens, water 

 heaters, and industrial heating devices. 



More tractor evidence (Anier. Thresherman, 19 (1917), No. 11, pp. 17-19)' — 

 Tabulated data covering the operations of 59 large tractors and 37 small 

 tractors for the past year are reported and compared with similar data for 

 the two previous years. 



Fifteen of the large tractors used gasoline and 44 used either kerosene or 

 distillate. Among the smaller machines, 27 used gasoline and only 10 reported 

 the use of kerosene. In the cases of 42 of the large tractors and of 30 of the 

 small tractors, operation was cheaper than by use of horses. 



"As regards tractor sentiment, 40 owners of large tractors -eport local senti- 

 ment favorable, as against 31 two years ago. In 12 communities the replies 

 are unfavorable, while in the remaining 7 they either do not reply or are unde- 

 cided. Out of the 37 owners of small machines, 33 reported favorable senti- 

 ment last year and only 30 this year." 



