Sacramento Cal. and "10" on 1852 letter from gold fields to Maine

Nice and interesting letter to a brother with advice on whether to come to the gold fields of Calif. Letter is headed Placer City Cal. in 1852. "...the mines are getting rather poor now. I have seen a multitude of people pass up this valley for the last three months and the most of them from the New England states and some of them sorry they had come some glad..." Don't stop in Sacramento or the valley in the summer it is very sickly... Also says to get a through ticket or you may be detained on the isthmus where about 3500 people are on account of not having a through ticket. Letter is to Nathaniel Holly in North Whitfield, ME>