_Siskiyou._--Siskiyou county lies east of Del Norte and Klamath, is forty miles wide from north to south, one hundred miles long from east to west, and reaches to the eastern boundary of the state. It has a population of 7,629, the large majority of whom are engaged in mining. The mining district is all in the western end of the county, along the banks of the Klamath River and its tributaries, the Scott and Shasta Rivers. The Klamath runs through a deep _canon_; the Scott and Shasta Rivers, have pleasant open valleys, but the diggings along their banks are chiefly among the _canons_ near the Klamath. Hydraulic and tunnel claims are rare. There are six quartz-mills in the county, and fifteen mining ditches, of which last the principal is the Yreka canal, forty miles long, bringing water from the head of Shasta River to the town of Yreka. In 1859, there were four quartz-mills in the county, one of which was at Mugginsville, one in Scott's valley and two in Quartz valley. I have no information about the situation of the two built since that time. The principal mining towns are Yreka, Scott's Bar, Hawkinsville, Johnson's Bar, Deadwood and Cottonwood. _Trinity and Shasta._--South of the western part of Siskiyou and the eastern part of Klamath, lies Trinity county, ninety miles long from north to south, and about twenty miles wide on an average. The northern part of the county is the basin of the Trinity River, and is auriferous. From the county assessor's report for 1860, it is to be inferred that there is not a quartz-mill or a mining-ditch in the state. The county is very mountainous, and most of the mining is done in rugged _canons_ along the Trinity River. The chief mining towns are Weaverville, Cox's Bar, Big Bar, Arkansas Flat, Mooney's Flat and Trinity Centre. South of Siskiyou and east of Trinity lies Shasta county, which is on an average forty miles wide from north to south and one hundred miles long, reaching to the eastern border of the state. There is a rich auriferous district about twenty miles square, in the vicinity of the town of Shasta, in the south-western part of the county. The diggings are mostly in the basins of Clear Creek, Cottonwood Creek, Rock Creek and Salt Creek, all of which enter into the Sacramento. There are four quartz-mills in the county, one at French Gulch, one at Middle Creek, one at Muletown, and one at Old Diggings. The county has twenty-seven mining ditches, with a joint length of one hundred and forty-one miles, an average of five miles each. The chief mining towns are Shasta, Horsetown, French Gulch, Muletown, Briggsville, Whiskey and Middletown.