Definition of "gripsack"

As for Bondell's gripsack, it was inconceivable that forty pounds could weigh so much. It pressed him down like a mountain, and he looked back with unbelief to the year before, when he had climbed that same pass with a hundred and fifty pounds on his back. If those loads had weighed a hundred and fifty pounds, then Bondell's grip weighed five hundred.

1910, Jack London, “Trust”, in Lost Face

“Well,” drawled Nares, “there's sixty pounds of niggerhead on the quay, isn't there? and twenty pounds of salts; and I never travel without some pain-killer in my gripsack.”

1892, Robert Louis Stevenson, Lloyd Osbourne, chapter 11, in The Wrecker, London, Paris: Cassell & Company, […]