- M.U.S.C.1
- MCSSC1
- MIZZY Incorporated, Clifton Forge, VA1
- MacGregor Instrument Co., Needham, MA1
- Mager & Gougelmann, New York, NY1
- Marshall1
- Mathieu, Auguste 1872-19291
- Maw & Sons, London1
- McCourt Label Cabinet Co., Bradford, Pennsylvania1
- McKesson Appliance Co., Toledo, Ohio USA1
- Medical Society of South Carolina1
- Metallic Art Co., New York, New York1
- Milex, Weatherford, Texas1
- Millikin, London, England1
- Mitutoya1
- N.V. Rudolph & Co., Richmond, Virginia1
- Naturalizer1
- Nelson, Baker Co., Detroit, Michigan1
- New Imperial Company1
- Noyes, Henry D. (Henry Drury) 1831-19001