Definition of "dumbly"

On the flat behind the mill, dawn-rising Chinamen shogged with nimble bare feet under their yoke-linked watering-cans. These busy brethren, meeting sometimes on the same narrow track, would pause, ant-like, seemingly to dumbly regard one another and their burdens, then, still ant-like, pass silently to their work.

1907, Barbara Baynton, edited by Sally Krimmer and Alan Lawson, Human Toll (Portable Australian Authors: Barbara Baynton), St Lucia: University of Queensland Press, published 1980, page 147

I handed it dumbly to my friend, who had the grace to giggle.

1946, George Johnston, Skyscrapers in the Mist, page 32