Definition of "lowness"

Then I was forced to rest; and, sitting down on the ground, saw that the glimmering streak of light had faded, and that the awful blackness of the previous night was creeping up again. And now I had no heart to face it, being cowed with hunger, thirst, and weariness; and so flung myself upon my face, that I might not see how dark it was, and groaned for very lowness of spirit.

1898, J. Meade Falkner, “In the Vault”, in Moonfleet, London, Toronto, Ont.: Jonathan Cape, published 1934, page 65

My attention was attracted to the next box [booth] by a conversation which was, from its lowness, evidently intended not to be heard.

1861, E. J. Guerin, Mountain Charley, page 19