Sentence:  I got a spade from the tool-house, and began to <WSD>delve</WSD> with all my might - it scraped the coffin; I fell to work with my hands; the wood commenced cracking about the screws; I was on the point of attaining my object, when it seemed that I heard a sigh from some one above, close at the edge of the grave, and bending down. 
Meaning of the word marked with <WSD> tags:  To dig the ground, especially with a shovel.