Slater was born in England in  Nov. 1826   and emigrated to New York in 1841. In 1865 he was partnered  with S.T.Gordon, as Gordon & Slater.  He was later partnered with G.R. Martin, and H. Distin. In 1885 he advertised as "mfr of brass and silve rotary. ordinary piston valves, and patent light valves - valved band instruments".  He was at the address of  42 Cortland St New York from 1875-88. He died in 1920. See also an earlier Slater Tenor c.1865.  This horn will soon be renovated. Note the bottom sprung Perinet style valves.