1920) EURAL ENOINEEEING. 391 



" Extensive investigations and experiments have shown that to be most effec- 

 tive and siitlsfactory snch iHiuipment for tlirashers should embody as many as 

 possible of the following general points of design and construction: (1) A cen- 

 trifugal type, steel-plate exhaust fan is most desirable. (2) A single-inlet- 

 typc fan lias the advantage of offering the least obstruction to the deck. (3) 

 The fan drive should be as direct as possible from the cylinder shaft. The fan 

 pulley should be as large as practicable to prevent undue slippage of the belt 

 A minimum diameter of 4 in. is suggested. (4) A light running fan of simple 

 but rigid construction, securely attached to the frame of the separator, answers 

 the puri>ose best. (5) Ample exterior bearings should be provided, with no 

 overhang of the shaft. (6) For medium sized machines, ranging from 26 to 46 

 in. to 32 by 54 in., the fan should have a peripheral speed of approximately 

 6,500 ft. per minute, with a capacity under field conditions of from 35 to 40 

 cu. ft. of air per second. These values would be slightly greater for the larger 

 and slightly less for the smaller machines. ... (7) The eye or inlet of the 

 fan should be located opposite tlie fun pulley at the center of the casing. The 

 discharge pipe should have an area at least as great as that of the inlet. . . . 

 (8) The intake hood should be tapered and the intake should cover a deck area 

 of not less than 600 sq. in. (9) The intake should be centered and plactnl at a 

 forward position on the deck. On most machines this location would be over 

 the beater. (10) If straw, grain, or other heavy material is thrown upward 

 into the fan intake by the beater or cylinder of tlie separator, it will be neces- 

 sary to place a deflection plate or bafile board, preferably metallic, under the in- 

 take at an angle of approximately 30° with tlie deck. (11) The absence of 

 sharp, abrupt curves or bends in the intake and connecting parts is most im- 

 p<jrtant. . . . (12) The fan discharge should be conducted through a metal 

 pipe to the rear of the separator, thence by a canvas tube into the base of the 

 straw stack." 



Concrete and steel fence posts, J. J. Crumley (Mo. Bui. Ohio Sta., 5 (1920), 

 No. 4j PP- 107-110). — Studies extending over two years of some 10,000 concrete 

 and steel posts in service are briefly reported. 



The concrete posts were round, rectangular, triangular, T-shaped, and flat on 

 one side and round on the other. It was found that the type of reinforcement 

 has a very important bearing on durability, its most important influence being 

 on the tendency of the post to disintegrate. Thin flat strip and broad corru- 

 gated stt'cl reinforcing were failures. Better results were obtained by the use 

 of six No. 9 smooth wires. The results indicate that the reinforcement should 

 be in compact form, either square or round, and should not be too close to the 

 surface of the post. The two principal sources of weakness found in concrete 

 posts were tendency to disintegrate and brittleness. 



The steel posts were found to differ considerably from concrete in their 

 period of use. " The f(>nces examined seem to indicate that the quality of 

 metal of which the posts are made is a greater factor in durability than the 

 covering of paint, or even of zinc. Taking into account the various types of 

 steel posts, the fences examined would place this material in a class about with 

 white cedar. The examination of tliese 10,000 concrete and steel posts in actual 

 service in fences seems to indicate that these two materials, especially the con- 

 crete, hav(> fallen far below what was expected of them." 



Preservative treatments for willow fence posts, K. E. Blaib {U. S. Dept. 

 Affr., Dept. Circ. 15 (1920), pp. 76, 77).— ExiMjriments at the Yuma Reclamation 

 Project Experiment Farm on tlie preservative treatment of 419 willow fence 

 posts, not less than 5 in. at the smallest diameter, are reported, showing that 

 placing the posts in commercial creosote maintained at a temperature of 200° 

 F. for two hours gave the best results. The next best results were obtained by 



I 



