S. R. Leland & Son was established in 1839 as a music publisher and pianoforte dealer by the founder Samuel Reeves Leland. The earliest publication that I have is sheet music dating to 1842 showing their address as 8 Brinley Row, Worcester, Massachusetts.
By 1879 their address was 446 Main Street, Worcester and their circular says they dealt in band instruments, sheet music, Chickering & Sons' piano-fortes, organs by Mason & Hamlin, J. Esty & Co. and Wilcox & White, and pianos by Weber, Haines Brothers, Mathushek and Hallet, Davis & Co.
In about 1883, they started making brass instruments with Carl Anger as superintendent. Their 1885 catalog tells of the death of Samuel and that his son Frank was now the head. At this time, they dealt in Missenharter instruments as well as their own "Light Piston" line. They also offered instrument repair, cases, music stands, rentals, banjos from Fairbanks & Cole, S.S. Stewart, Artist, Crescent and Dobson, violins by William Peters, Buffet clarinets, drums, uniforms and sheet music.
One humerous quote from the 1885 catalog is that, "The proper band for a female to belong to is a hus-band. She can usually play him for all he is worth."
They sold Missenharter instruments from 1883 until 1886 then Leland started making their own Eclipse model cornets in 1886. These lasted until they closed shortly before Frank's death in 1915.
See the "History" section for a more detailed timeline and my calculations for dating all their brass instruments.