On June 30, 1838, U.S. Patent No. 821 was granted to the brothers Philos Blake, Eli W. Blake, and John A. Blake, of New Haven, Connecticut, on a furniture caster.

The inventors were nephews of Eli Whitney, with Eli W. being his namesake. The brothers established a hardware casting and furnace works in 1835 in the Westville section of New Haven. The company manufactured door locks, latches, hinges, and other items of domestic hardware — many of which they eventually patented. The brothers no doubt gained valuable engineering skills at the Whitney Armory, their uncle’s arms factory, which they continued to run for 10 years after Whitney’s death.

A little more than seven year later, the brothers had their patent reissued: