When was John Slater elder brother born? 
John Slater (industrialist): John Slater (December 25, 1776–1843) was an early American industrialist, founder of Slatersville, Rhode Island and younger brother of Samuel Slater, father of the American Industrial Revolution, and a member of the well-known Slater family. Samuel Slater: Samuel Slater (June 9, 1768 – April 21, 1835) was an early English-American industrialist known as the "Father of the American Industrial Revolution" (a phrase coined by Andrew Jackson) and the "Father of the American Factory System."
June 9, 1768