The button's backmark is definitely "Scovills & Co. Waterbury". It dates strictly from 1840 to 1850. The company's name changed to Scovill Manufacturing Company in 1850. My info source is the book "American Military Button Makers And Dealers; Their Backmarks & Dates" by William F. McGuinn & Bruce S. Bazelon. It is an essential book for every button-digger and collector. It is commonly available on Ebay for about $30. Many civil war relic shops also sell it.