Rufus Nichols and Edward Childs had a partnership in Conway MA making revolving firearms in the late 1830s. Their patent was granted in 1838, for an indexing mechanism that linked the cylinder to the hammer. However, the guns also used a spring loaded cylinder with nested cones on the mouth of each chamber to prevent gas leakage. The cylinder had to be manually unlocked before it could be rotated, and then manually locked again before firing. Interestingly, some of their rifles (like this one) omitted the indexing mechanism entirely, leaving the shooter to line up the cylinder by hand. In total, the pair made 100-150 rifles in both .36 and .44 calibers, and about 2 dozen pistols.