The 'Rocky Mountain News' of Oct. 31st contains the account of the death of the Hon. James M. CAVANAUGH which took place at Leadville the previous day. In its notice of the deceased the 'News' states that Mr. Cavanaugh was born near the city of St. John, New Brunswick in 1822. He read law in Worcester, Mass. and went to Colorado in 1861. He immediately secured a large practice and was the Democratic candidate for Congress in the same year. In 1866 he went to Montana and represented that Territory for two terms in the National Congress. At the expiration of the second term he settled in New York city, where he remained until he concluded to resume his residence in Colorado.