1919] , RURAL ENGINEERIlirG. 585 



Results of long-time tests of creosote treated fence posts, C. H. Teesdale 

 (Engin. Netvs-Rec, 82 {1919), No. 26, p. 1254) -—Tests, conducted by the Forest 

 Service of the U. S. Department of Agriculture in cooperation with the Uni- 

 versity of Minnesota on over 2,000 fence posts treated and set during 1908 and 

 1909 are reported. 



At the last inspection in 1918, 73.5 per cent of the basswood treated with 

 coal-tar cresote and 78 per cent of that treated with water-gas-tar creosote were 

 still sound. In the case of red oak 94.5 per cent treated with coal-tar creosote 

 and 92.5 per cent treated with water-gas-tar creosote were still sound. It was 

 found that the basswood posts did not take the treatment well, and for this 

 reason tlii.s species is not recommended for open-tank treatment. 



Pencing the farm, W. J. Rutherfokd (Saskatchetvan Dept. Agr. Bui. 51 

 {1911), pp. 12, figs. 10). — Thi.s bulletin gives general information on farm fenc- 

 ing, with special reference to Saskatchewan conditions. 



With reference to posts it is stated that, " In all the tests that have been 

 made with wood, round cedar posts 4 to 6 in. at the small end, cut green in 

 December or January, peeled and seasoned, are the most durable, the life 

 being about 18 to 20 years. The less sapwood the longer lived will be the 

 Ijost, other things being right. Creosoting timber helps to prolong its life. 

 Split cedar posts are cheaper and, if creosoted, give very good satisfaction. 

 Tamarack and spruce are used, but their life is not so long as cedar. Willow 

 and poplar are constantly needing repairs and substitutions after 3 years 

 of use." 



It is also stated that a number of years of experiment with steel posts 

 have proved them strong and durable. 



"A very effective fence for all practical purposes, except the turning of 

 coyotes and dogs, is the 8-strand 45 in. fabric with one barb wire placed 8 in. 

 above. All these woven wire fabrics should be made of No. 9 gauge horizontals 

 and 11 or 12 gauge uprights, the latter being placed 12 to 16 in. apart. The 

 larger wire is stronger and is better galvanized, which means longer life for 

 the fence and less repairing." 



The Diesel engine: Its fuels and its uses, H. Haas {U. S. Dept. Int., Bur. 

 Mines Bui. 156 (1018), pp. riII+133, pis. 16, figs. 57).— This report discusses 

 recent developments in the design and construction of the Diesel engine, the 

 fuels suitable for burning in it, and the uses to which it is particularly 

 adapted, with special reference to medium and small power requirements. 



With reference to economy, it is stated that although explosion oil engines 

 are materially cheaper in first cost they consume considerably more fuel and 

 lubricating oil than Diesel engines. Their fuel consumption at fractional 

 loads also increases at a greater rate. 



"The mechanical efficiencies of four-stroke engines at full load vary from 

 75 to 82 per cent, 80 per cent being usual for high-gi-ade, low-speed engines 

 of medium and large powers. The engine efficiency, exclusive of the air com- 

 pressor, is 85 to 90 per cent. The mechanical efficiency of engines having a 

 two-stroke cycle .seldom exceeds 70 per cent and may be as low as 65 per cent 

 in high-speed engines." 



" The indicated thermal efficiency of the Diesel engine having a four-stroke 

 cycle varies from 45 per cent at full load to 47 per cent at half load, and 

 the effective thermal efficiency from 37 per cent at full load to 30 per cent at 

 half load, which represents the best practice. As regards engines having a 

 two-stroke cycle, the figures are 10 to 15 per cent lower." 



"The volumetric efficiency of engines having a two-stroke cycle is generally 

 below unity. For slow-speed four-stroke engines a volumetric efficiency of 90 

 144402°— 19 7 



