Silver and Denim is the name of a manufacturing company. This company could trace its history back to 1854, although the "Silver & Deming" name does not date back that far. The titular heads were Albert R. Silver and John Deming. Silver & Deming made a variety of machines that were primarily aimed at wheelwrights: hobboxing machines, spoketenoning machines, etc.
Silver & Deming apparently invented the largesize twist drill bit with a turneddown shaft so they can be used in a chuck smaller than the bit's cutting diameter. They did not patent this idea, so the idea was quickly copied by others, but these bits are still called "Silver & Deming drills".   _{Your Comment}