1»20] RURAL ENGINEERING. 483 



anil spij^ot joints is only from 25 to 50 per cent of the cost when they are 

 calked with lead. 



The ineohaiiiral i»roi)orties of West African " pooli " timber (Bui. Imp. 

 Inst. [London], 11 (1919), No. S, pp. 277-280).— Tests of the compressive, 

 •^ii'-aring, and cross bending strengths of four samples of so-called pooli timber 



rived from Cordia platythyrsa and found in Sierra Leone and in the Gaboon, 

 -Nigeria, and Cameroons showed that it equalled the average coniferous tim- 

 bers used in the United Kingdom in compressive strength and exceeded them 

 in bending and shearing strengths. The weight per cubic foot varied consider- 

 ably but was about the same as that of white pine. 



Lubrication of internal-combustion eng,ines, W. F. Osborne (Poicer, 51 

 (1020), No. 15, pp. 5.0()-593).— Beginning witli a discussion of the action of 

 lubricants during each stroke, this article takes up in detail the various con- 

 struction and operating conditions which affect the choice of oil for internal- 

 combustion engines. A list of lubricating troubles is given, together with the 

 causes of each. 



Low-grade fuel requires new valve adjustment, J. P. Mahoney (Agri- 

 motor, 3 (1920), No. 7, p. 13). — The results of experiments on valve adjust- 

 ments of gas engines i-equired on accoimt of the present low-grade fuels on the 

 market indicate that tappet clearances should be increased to prevent valves 

 from being held open when the engine is liot. Valve tappet clearances are advo- 

 cated as follows: "For engines from 3i-in. bore by 5i-in. stroke to 4i-in. bore 

 by 5i-in. stroke — intake valves 0.008 in. ; exhaust valves 0.012 in. For engines 

 frym 4j-in. bore by G-in. stroke to 5-in. bore by 6^-in. stroke — intake valves 

 O.of in.; exhaust valves O.OIG in. Never less but rather more than these clear- 

 ances should \w given." 



Uei)ort of the ])ei)artniental Committee on Agricultural Machinery, to- 

 gether with appendix and summaries of evidence (London: Min. Agr. and 

 I : <luric-s, 1920, pp. 11+75; abs. in Impl. and Mach. Rev., 45 (1920), No. 5^0, pp. 

 r,S7-1790). — This is the report of a committee of eight appointed to arrange 

 for the testing, adaptation, and improvement of machines likely to prove of 

 value to agriculture; to examine inventions and new devices; and to advise as 

 to the further steps which should be taken in England to promote the develop- 

 ment of agricultural machinery. 



Among the recommendations of the committee are included sections for 

 research, standardization, testing, popular information, education, and advice 

 and propaganda on agricultural machinery. It is to be noted that the recom- 

 mendations of this conunittee propose to consolidate functions on the develop- 

 ment of agricultural machinery in England which are widely scattered amongst 

 engineering .societies and State and Federal institutions in the United States. 



Handy charts for belts (Tractor and Gas Engine Rev., 13 (1920), No. 4, p. 

 11^, fig. 1). — A chart is presented giving data on the transmission of horse- 

 power by different types and widths of belts at varying speeds. 



How to use the j)Ost drill press, G. H. Radf.baugii (Power Farming, 29 

 (1920), No. 5, pp. 14, 15, IS, 20, figs. 23).— The proper use of the post drill press 

 is described ami profusely illustrated, with particular reference to the repair of 

 bi-(iken farm machinery. 



The horse-power problem on the farm, O. A. .TirvE (U. S. Dcpt. Agr. Year- 

 hook 1919, pp. 485-495, pi. 1, figs. 7). — A discussion of the choice of farm 

 power with particular reference to the use of horse power is given. This is 

 bused upon results obtained with horse power on a number of representative 

 farms. 



It is shown that there are large variations in the number of hor.ses \ised 

 even for the same operation in different sections of the country. Other factors 



