RECONNAISSANCE OF SOUTHEASTERN LUZON. 479 



roads and in concrete constniction. A number of quarries have been 

 opened by the district engineers. A large amount of gravel from the 

 rivers is also used. 



Clay. — ^Native pottery is made at the barrio of Bolo near Tiui. The 

 clay employed has been formed by the disintegration of a gray pumiceous 

 stone which contains yellowish mica, some specks of which are seen in 

 the finished ware. Pottery is made also in the barrios of Gubat from 

 a clay which also contains mica and is somewhat similar in character to 

 that at Bolo. Alluvial clay is used in Saban, a barrio of Oas, and in a 

 barrio just north of Libmanan. 



The silicious clays at Tiui Hot Springs are used for painting the white 

 designs on the pottery made at Bolo. The red coating is given to some 

 of the pottery by washing it with ferruginous clay obtained from near 

 Buhi. 



A white clay resembling kaoilin is found near the San Vicente barrio 

 of Tinambac and is used for preparing a kind of cold water paint. 



'Salt. — At many of the coast settlements small quantities of salt are 

 made in a desultory manner by evaporating sea-water. On Calagua 

 Island salt making is carried on as an industry. However, the greater 

 part of the salt used is imported. In some places where sea-water is 

 not available and the nipa palm grows, this plant is burned and the 

 ashes are leached and then evaporated to obtain salt. 



Artesian and deep tubular wells. — ^Wells have been sunk with jet rigs 

 in the Bicol Valley in Camarines Province, at the towns of Nueva Cace- 

 reSj.Bato, Buhi, Nabua, Calabanga, San Fernando, Milaor, and Cama- 

 ligan. The Province of Albay contemplates the drilling of wells in the 

 upper part of the same valley, in a portion of which the conditions are 

 favorable for using a jet rig. 



The use of water from the wells already drilled has been found valu- 

 able in combating occasional outbreaks of cholera and improving general 

 health conditions. 



REFERENCES. 



Abeixa y Casabiego, Enrique. El Mayon, o volean de Albay (Filipinas). Ma- 



' drid, Tello (1885), 23 pp., 2 pi. 

 Idem. Emanaciones volcftnicas subordinadas al Malinao (Filipinas). Madrid, 



Tello (1885), 14 pp., 3 pi. 

 Beckee, Geoege F. Report on the Geology of the Philippine Islands, Annual 



Rep. U. 8. Geol. Surv. (1899-1900), III. 

 BuBEiTT, Chaeles H. The Coal Measures of the Philippines. A rapid history 



of the discovery of coal in the Archipelago and subsequent developments. Rep. 



U. S. Military Govt, in the Philippines. Washington (1901). 

 CoEONAS, Jos£. La erupcion del volcSn May6n en los dfas 25 y 26 de Junio, 1897. 



Observatorio de Manila ( 1898) , 55 pp., 2 maps., 2 pi. 

 Dbache. R. von. Fragmente zu einer Geologic der Insel Luzon ( Philippinen ) . 



Vienna (1878), 5 pi., (inchiding 2 maps.). 



