Gold and Silver production in 1914 Page 26



	854 MINERAL RESOURCES, 1914----PART I.

	successful. In the Philippine Islands dredging had its inception under the Spanish regime in a curious native boat of diminutive scale but was first tried by modern American methods (unsuccessfully) in Masbate in 1905. Later New Zealand and American dredges were introduced into the Paracale-Mambulao district, southeastern Luzon, where the first native dredging was done, and the development of the industry has been continuous since. One modem dredge alone had recovered more than $450,000 in less than 2J years to the end of 1914 and had paid 107 per cent interest on the original capitalization of $250,000. There were 8 dredges at work in 1914 in the islands, 7 in this district and 1 in Tayabas, and they produced altogether during the year about $515,000. In California some of the earliest attempts at dredging for gold were made, following the first successful work of the kind with steam-driven bucket-elevator dredges at Otago, in New Zealand, in 1882. But it was not until 1896 that the first commercial bucket-elevator dredge of the California type was operated on Yuba Kivcr. It was later wrecked by floods, but it began the great output of gold from California by this method which had amounted to over $71,000,000 by the end of 1914, in which year 60 boats altogether were at work in the various fields. Much of the proved dredging ground in California has now been worked out, and it is an open question whether development of new ground will in the future take the place of that worked out. In the evolution of dredging apparatus from the small steam-driven wooden machines with buckets of a capacity of about 3 cubic feet each and capable of raising 1,200 cubic yards daily to the giant all-steel electric-driven dredges with buckets raising 16 cubic feet each and handling 10,000 cubic yards daily, California has earned first rank. It is becoming better known that a great deal of dredging in various parts of the world has been at a loss and that many important factors enter into the problem as to what ground can be worked at a profit by this method. The industry has now developed f ;eologic, engineering, and constructing experts, and, in view of the act that even profitable dredging is expensive in outlay, prospective investors would seem to gain something by consulting the rich fund of experience now available in the hands of these specialists. Brief details of dredging operations have been given in Mineral Resources in the mines reports on gold, silver, copper, lead, and zinc of the Western States and also in earlier reports of the Director of the Mint. Further information is to be found in reports of geological surveys or mining officials of different States. A comprehensive and very useful report is contained in Bulletin 57 of the California State Mining Bureau, "Gold dredging in California," by W. B. Winston and Charles Janin. Another valuable treatise is ' 'Dredging for gold in California," by D'Arcy Weatherbe, pubhshed by the Mining and Scientific Press; and additional information is constantly furnished by the technical press. The following table, compiled from best available sources, gives the dredge production of gold in the United States and Alaska (not including the Philippine Islands) from 1896 to the end of 1914, inclusive, by States: