Definition of "unclasping"

Nothing had been said during our drive, but the high thin breathing of our new companion, and the claspings and unclaspings of his hands spoke of the nervous tension within him.

1892 [January], A[rthur] Conan Doyle, “Adventures of Sherlock Holmes. VII.—The Adventure of the Blue Carbuncle.”, in Geo[rge] Newnes, editor, The Strand Magazine: An Illustrated Monthly, volume III (January to June), number , London: George Newnes, Limited, […], page 82, column 2