Born in Bethlehem Township, New Jersey, Cornish attended the common schools.

He was graduated from the Easton (Pennsylvania) Business College, and engaged in the manufacture of pianos and organs.

He served as member of the New Jersey Senate from 1891 to 1893, representing Warren County.

He accompanied William Jennings Bryan on his whistle stop tour through New Jersey, pausing in Washington on September 23, 1896.

[1] After leaving Congress, Cornish again served as a member of the New Jersey Senate from Warren County from 1900 to 1902 and 1906 to 1911.