some have their water-level artificially raised by dams, as in the 

 case of Lake Thirlmere; and others are artificially formed by im- 

 pounding the waters of streams or rivers, as the Lake Vyrnwy in 

 Montgomeryshire, another example being the reservoirs from the 

 rivers Elan and Claerwen. 



In Great Britain, however, there is usually little need of irri- 

 gation, for there are but few districts that do not receive an ample 

 supply of water in the form of rain, and a serious drought is of 

 rare occurence. 



D. A. WILLEY. Irrigation and Engineering. Cassier's Magazine, 

 an Engineering Monthly. April 1910. London, p. 663. 



An important article on the irrigation schemes in the United 

 States, with many illustrations. 



XVI. 



Tillage. Tilth. Influence of tillage, of drainage and of soil- 

 conditions generally on root development. Economy of 

 soil-moisture. Trenching. 



W. FREAM. Elements of Agriculture. A Text-Book prepared 

 under the authority of the Royal Agricultural Society of 

 England. Seventh Edition. Thirty-ninth Thousand. Pp. vui-|- 

 480 with fgs. 256. London, 1910. 



The following are extracts from the prefaces to the first and 

 fourth editions: 



"The preparation of this Text-Book was undertaken by the 

 Royal Agricultural Society of England, in compliance with the 

 many demands that had been addressed to it for an elementary 

 work on Agriculture adapted for use in rural and other schools 

 and classes. 



The general scheme of the work was settled by a Sub-Com- 

 mittee appointed by the Council of the Society, and consisting of 



