Help Needed With R41A Cancel Research

Recently purchased this R41a pair and am trying to learn about the handstamp cancel from the Brothers McKim of 1863. I have no State to go by as a reference. Please advise the method to the madness in looking up business cancels on early revenue stamps. Is there reference material out there for this? I have numerous reference books within my library for railroad cancels and insurance cancels but have not been able to determine this one.

Thank you for looking and any advice, guidance or assistance would greatly be appreciated in how you research cancels.

Thank you, Richard

I don't know of any complete reference that would identify various businesses, etc., that would have used revenue cancels such as your example, but I do know that McKim Brothers was a banking house, originally in Baltimore, and later on Wall St., New York City.

This period ad is from the NY Times (1863):



If you are seeking biographical information on William McKim and his family, this information will be of interest (and is probably more than you want to know)!

Thank you Wt1 for your help and excellent reference material you provided.

Many cancels are unattributable without finding them on document. A cancel such as "R.B. & Co." or "T. L." gives you VERY little to go on without context.

Google is where the most helpful information comes from for me. I know some collectors that own copies of New York and other city directories from the 1860s.

Sometimes, even if there is not a year given in the cancel, adding a Civil War year to the Google search will help constrain results.