AGRICULTURAL ENGINEERING. 697 



12 samples of well water, and 3 samples of pond water. From these 

 analyses the amounts of white and black alkali per 100,000 lbs. and per 

 acre inch are calculated and the adaptability of the different waters to 

 irrigation purposes is discussed. Various suggestions are made regard- 

 ing the construction of an irrigation plant, including dimensions of the 

 reservoir and the capacity of pumps and windmills. Analyses with 

 reference to sanitary condition of 12 samples of water are appended. 



The forces which operate to destroy roads, with notes on road 

 stones and problems therewith connected, 0. L. Whittle ( U. 8. 

 Dept. Agr., Office of Road Inquiry Circ. 29, pp. J J, pis. /). 



"Other things bemg equal, the endurance of a roadbed depends upon the qualities 

 of the stone used, assuming the road to be properly constructed and adequately 

 drained. A road is subject to attack and consequent loss of material in part by rea- 

 son of the composition of the road rnetal of which, it is composed. The means of 

 attack brought to bear upon the surface of a road, in the order of their importance, 

 arc physical, dynamical, and chemical. 



''The physical agencies are (1) the disrupting effects of frost, both on the integrity 

 of the roadbed as a whole and on the individual rock fragments ami minerals; (2) 

 the transporting power of water in gullying the road, in washing particles of sand 

 and clay to the side drains and ditches, and the sorting action of water whereby the 

 winds are given better access to the liner and lighter parts of the products of road 

 wear; (3) the transporting power of the winds; (4) the attrition and weakening 

 effect of falling rain: (5) gravity. 



''The dynamical agencies are (1) friction, which results from the grinding action 

 of one fragment of rock against another under the action of carriage tires and the 

 feet of animals; (2) the impact resulting from the same causes; (3) the disrupting 

 effect of roots. 



"The chemical agencies are (1) decomposition, shown, for example, by the disin- 

 tegration of the feldspar-bearing rocks whereby the feldspars and other minerals are 

 converted into clay, quartz, calcite, etc.; (2) solution, or the power possessed by 

 surface waters impregnated with acids to dissolve most rocks and the products of 

 decomposition of others and carry them away." 



These different agencies are discussed in detail, as well as the essen- 

 tial qualities of road stones, the relation of decomposition to cementa- 

 tion, and the effect of moisture on a roadway. The structure of different 

 classes of stone, including diorite, diabase, marble, and granite, are 

 shown in plates made from microphotographs of sections of the stone. 

 The planting of trees along highways is advocated and the chestnut is 

 especially recommended for this purpose. 



Irrigation in New Jersey, E. B. Vookhees {New Jersey Stas. Bpt. 1896, pp. 185-232, 

 pis. 5). — This article form3 part of Bulletin 36 of this Office (E. S. R., 9, p. 97). 



Trials of farm machinery, W. Molse (Biet [Helsingfors], 18 {1897), No. 5-6, pp. 

 141-144.) — The trials were conducted under the auspices of the Nyland and Tavas- 

 tehus County Agricultural Society (Finland) and included tests of mowing machines 

 (7) and planters and cultivators (10). 



Trial stations for agricultural machinery and apparatus {Landtmannen, S {1897), 

 No. 33, pp. 457-460). — Contains regulations for the trial stations for testing agricul- 

 tural machinery and apparatus recently established at the agricultural and dairy 

 institutes of Ultima and Alnarp (Sweden). 



Agricultural machinery in Germany and England, M. Langballe {Aarsber. 

 Qffent. Foransl. Landbr. Fremme, 1896, pp. 3.29-J41). 



