494 EXPERIMENT STATION RECORD. [Vol.36 



In the second series of experiments, the mortar mixtures used were 600 kg. 

 of cement per cubic meter of fine sand, 500 kg. of cement per cubic meter of 

 coarse sand, and 400 kg. of cement per cubic meter of gravelly sand containing 

 a large amount of grains of a diameter varying between 5 and 20 mm. The 

 proportions of oil used were 3 and 5 per cent of the weight of the cement. It 

 was found that, with the exception of some of the tests on the fine sand mortar, 

 the mortar containing 3 per cent of oil was less pervious than that without oil. 

 AVhen 5 per cent of oil was used the results in this respect were very variable. 

 At the higher heads these mortars were more pervious than the mortar con- 

 taining 3 per cent of oil. The addition of 3 per cent of oil did not appreciably 

 decrease the strength of the mortar or its power of adhering to iron. The 

 results as a whole are taken to indicate that 3 per cent of oil may be used to 

 advantage in cement mortar. 



See also a previous note by the author (E. S. R., 30, p. 889). 



The influence of compression in internal-combustion engines, R. E. 

 Mathot (Power, 43 (1916), No. 15, pp. 512-514, fidS- 2).— It is shown that 

 within certain limits neither the amount of compression nor the heat value of 

 the fuel affects the output of the engine, although the former does affect the 

 economy. 



Tables of data from actual practice covering over 600 tests on about 40 

 dilTerent makes of internal-combustion engines are also included, showing the 

 proper mixtux'es and compressions to be used with different fuels in order to 

 attain the best results. 



Some eng'ine plow troubles and their remedies, C. O. Reed (Amer. Thresher- 

 man, 18 (1916), Nos. 11, pp. 68, 69; 12, pp. 14, 15, figs. 5).— Information regard- 

 ing the prevention of excessive draft, failure to scour, uneven furrow crowns, 

 and failure to penetrate is given, together with brief instructions regarding 

 laying out fields and buying and starting a new plow. 



Recent inventions in machines for tilling the soil, M. Castelli (Intemat. 

 Inftt. Af/r. [Rome], Mo. Bui. Agr. Intel, and Plant Diseases, 6 (1915), No. 11, pp. 

 1424-1437). — This article describes some of the more recent improvements in 

 tillage machinery, dealing mainly with mechanically propelled types. 



Mechanical cultivating apparatus, M. Ringelmann (Rev. Vit., 43 (1915), 

 Nos. 1112, pp. 805-310; 1115, pp. 361-366; 1116, pp. 377-383).— A number of 

 types of mechanically operated tillage machines for use in truck and vineyard 

 work are described. 



Culture machinery, G. Coupan (EncyclopMie Agricole. Machines de Cul- 

 ture. Paris: J. B. Bailliere d Sons, 1915, 2. ed., pp. X/F+//80, figs. 376).— This 

 is a number of the Encyclop6die Agricole and deals in general with the ma- 

 chines and mechanical methods employed in the preparation of the soil, the 

 spreading of fertilizers and seeds, and the maintenance of culture. A large 

 amount of mechanical, mathematical, diagrammatical, and practical data 

 related to the construction and operation of the different machines is given. 



Experiments on the draft of a model plow under different working condi- 

 tions and their practical application, G. KtJHNE (Untersuchungen iiber den 

 Zugtvidcrstand cines Pflugwerkzcugmodelles bei verschiedenen Arbeitsbedin- 

 gungen und ihre Anwendung auf praktische Verhaltnisse. Inaug. Diss., Univ. 

 Oiessen, 1914, pp. 49, figs. 24). — The factors affecting the draft of a moldboard 

 plow are discussed, experimental apparatus is described, and laboratory ex- 

 periments with a model moldboard plow are reported to determine the influence 

 on draft of different physical factors under different working conditions in 

 soils artificially prepared. 



It was found in sand and loam soil that by steadily increasing the speed of 

 plowing under the same working conditions the plowing draft steadily in- 



