This is a small priming horn that belonged to an ‘L. Thomas’ who was a member of ‘Butler’s Rangers’, a provincial military unit of the British Army that was formed and led by a British loyalist named John Butler. https://en.m.wikipedia.org/wiki/Butler%27s_Rangers . At the outbreak of the Revolutionary War, John Butler and other loyalists fled to Canada and formed loyalist military units. The Rangers fought for the most part in western NY State but fought as far south as Virginia.  
This is an amazing piece of our early history and a rare little priming horn.