FROM FRENCH CORRAL TO NORTH SAN JUAN. 



380 





The main flume at French Corral is 4,500 feet in length, below which there are ten undercurrents 

 of varying length and either fourteen or twenty-one feet in width. The normal amount of water 

 used is 2,400 miner's inches, under a pressure of 130 feet. The nozzles are seven or seven and a 

 quarter inches in diameter. The top gravel has been pretty much removed as far as Kate Hayes 

 Flat, and the principal work now doing is on the lower bench. 



The tunnel at the Bed-Bock claim, between French Corral and Birchville, is 2,900 feet in length 

 to the first shaft. Work is still going on. 



The Birchville mines are practically exhausted, though Chinamen are at work cleaning up leased 

 portions of bed-rock. The exposed banks of gravel on the rim are mostly reddish in color, with 

 an occasional appearance of blue gravel in the deeper cuts and near the bed-rock. The material of 

 the gravel seems less liable to decomposition than that at Smartsville. 



Buckeye Hill I did not visit. There was not much doing at the time I was there beyond keep- 

 ing the tunnel and Humes in order and preparing for the future. There is said to be some deep 

 gravel left to work, besides the banks on the rim-rock. According to Raymond's report for the 

 year 1874, pages 126 and 127, the property is owned by an English company, and is worked 

 through a tunnel 5,000 feet in length. 



At Manzanita Hill there is a tunnel 2,3C>0 feet long, followed by 4,200 feet of flume and eleven 

 undercurrents. The grade is six inches to twelve feet. The pressure-box is at an elevation of 430 

 feet above the bed-rock, and the water is brought through a pipe of 4,000 feet in length. The 

 diameter of the pipe varies from twenty-two to thirty inches, and the iron used in its construction is 

 in part No. 14 and in part No. 12. The nozzles are seven and a half inches in diameter, and deliver 

 1,500 inches of water. According to Mr. Miller the pipe would not stand the pressure if the nozzles 

 were reduced to six inches, even if the quantity of water were reduced to one thousand inches. 

 The principal excavation at the present time is on the lower bench of gravel, the upper bench 

 having been removed for as much as a quarter of a mile to the northeast of the lower bank. The 

 blue gravel has to be loosened with powder and broken up witli sledges. The explosive used is 

 the Judson powder, which works more rapidly than common black powder, though not so rapidly 

 as the giant powder. According to Mr. Thomas, the captain of the mine, the richest gravel is 

 found in a stratum about fifteen feet above the bed-rock, some of the blue gravel on and near the 

 bed-rock being no richer than portions of the red dirt at the surface. 



The inch of water is measured by the Milton Company in a different way from that adopted at 

 Smartsville. The How through an aperture twelve inches wide and twelve and three quarters inches 

 high, when the water stands six inches above the top of the opening, is taken as two hundred 



* 



inches. 



The American Hill tunnel is 4,000 feet in length, and has a grade of ten to eleven inches in 

 twelve feet. Outside the tunnel there are several sets of tail sluices, connecting the undercurrents, 

 which are, according to my note-book, twenty in number, though in Raymond's report for the year 

 1875, page 95, the number is said to be "over forty." These undercurrents are generally from 

 twenty to twenty-four feet wide ; one of them is forty feet wide. The depth of the tunnel below 

 bed-rock at shaft No. 1 is 190 feet, but the distance between tunnel and bed-rock will diminish 

 rapidly as the banks are washed away gradually down the channel. 



There is a great deal of low-grade gravel at this point, and quite large masses are still standing 

 on the rims waiting for the time when water for was] ring can be obtained at a low rate. 



s 



The gold is generally line in the gravel of this district. It is seldom that a nugget worth as 

 much as five dollars is found. The finer gold at French Corral and at Manzanita Hill ranges 

 between 935 and 950 thousandths in fineness, the coarser between 925 and 930. Further data 

 upon this point are lacking. 



The statistics as to yield of gold which I was able to collect are not very complete. At Man- 

 zanita Hill a " clean up " of from fourteen to twenty-two thousand dollars is usually made at the 

 expiration of each run of thirty days of ten hours each, the final " clean up " in the fall of the year 

 yielding a much larger sum. Statistics in regard to the gold saved by the undercurrents are given 



