There was a feeble drumbeat under the rain. One ranger heard the notes of a xylophone. (xylophone: alternate name straw fiddle (historical), wooden clatter (historical)) Another heard only rain on a hollow log. (log: tree trunk, piece of timber) The patrol leader, usually unperturbed, heard in it an atavistic warning. (unperturbed: unruffled, composed, untroubled; atavistic: ancestral, primitive, throwback-like) A younger ranger thought the noise too desultory to be deliberate. (desultory: aimless, unfocused, haphazard) A third said damp leaves might attenuate a steady beat until only the loudest strokes reached them. (attenuate: weaken, diminish, lessen)
The sound was elusive. (elusive: evasive, slippery, subtle) A rise in the wind could impede their hearing; its abatement brought the rhythm back. (impede: hinder, obstruct, hamper; abatement: lessening, reduction, decrease) On a turn of the trail the ranger noticed an overturned skiff. From beneath it came three strokes, a pause, then a fourth. A missing camper was hitting its hull with her heel.
Asked later how she had kept up a relentless signal, the camper admitted she had spent most of the evening asleep. (relentless: unremitting, unrelenting, persistent) Her puppy, pleased to find so resonant a surface, had thumped its tail against the wood without a break.