796 EXPERIMENT STATION RECORD. 



"The soil on these lands is in every case of the very best kind for agriculture with 

 irrigation. It is usually an open, porous, limestone soil of sandy and gravelly tex- 

 ture, mixed with a little earthy loam. It is fairly deep and is underlain by a porous 

 limestone or coral, which affords the best drainage and probably renders it safe from 

 the danger of producing alkali. . . . 



"While the precipitation is insufficient, the perennial flow of the streams is unu- 

 sually abundant for a land requiring irrigation. The minimum discharges of these 

 streams where they would be diverted in the foothills are moderate in amount and 

 yet nearly sufficient for the irrigation of such areas as they command. ^Moreover, 

 the flood disc'Harges of these streams occur at frecjuent intervals throughout the year, 

 but are especially well distributed throughout the summer or rainy season. They 

 afford an abundant surplus for storage. The shapes of the smaller parting vallej's 

 and of the lower canyons through which the rivers emerge from the mountains give 

 every indication that abundant opportunities will be found, on fuller investigation, for 

 the construction of storage reservoirs at moderate expense and at relatively small cost." 



Irrigation has been practiced to some extent, especially on sugar 

 cane. The irrigation works which have been constructed correspond 

 in general typo with those of Mexico, but are usually of a more sub- 

 stantial character. Temporary distributaries, however, are used to a 

 considerable extent in the irrigation of sugar cane. 



"The volume of water available for utilization either as supply for domestic pur- 

 poses in the various cities or for conversion into power through the agency of water 

 wheels is relatively great. While this is especially true of the north side of the 

 island, it applies also in a measurable degree to the south side." 



The soils of the island are primarily of two classes — calcareous and 

 clay. In some localities they have been over cultivated without fer- 

 tilization and are now abandoned, but as a rule "the soil of Porto 

 Rico is so deep and fertile, the precipitation so abundant and well 

 distributed, and the temperature, though tropic, so mild as to render 

 it possible to cultivate almost all the land on the island." 



Supplies of fertilizers — green sand marl, guano, phosphates, etc. — 

 are abundant. 



Road making and maintenance, T. Aitken {London: Charles Griffin & Co., 

 190U, jip. Xyi^440, pis. l-i,fi(js. lis, dgms. 3). — "This treatise is divided into two 

 parts. The first relates to the making and the maintaining of macadamized roads, 

 while the second part deals with carriageways and footpaths." There is a prelimi- 

 nary historical sketch of road making and maintenance. Chapters are devoted to 

 the following subjects: Resistance to traction — wheels and weights on them; laying 

 out new roads, and the improvement of existing lines of communication; earthworks, 

 drainage, retaining walls, culverts, bridges, and protection of roads; road materials 

 or metal; quarrying; stone breaking and haulage; road rolling and scarifying; the 

 construction of new, and the maintenance of existing roads; carriageways and foot- 

 ways — preliminary remarks — foundations and pitched pavements; wood pavements; 

 asphalt jjavements; brick pavements, tar macadam, and miscellaneous materials used 

 for carriageways — conclusions; footways, curbs, channels, gullies, paving materials 

 for footpaths; and subways. Methods of carrying out the work and the cost of each 

 operation in the systematic making and repairing of roads and streets and the con- 

 struction and maintenance of carriageways and footways are given .in detail, the 

 information being for the most part the result of practical experience extending over 

 a number of years. The methods apply especially to English conditions. 



