Sentence:  A hundred Reeds, of a prodigious Growth, / Scarce made a Pipe, proportion'd to his Mouth: / Which, when he gave it Wind, the Rocks around, / And watry Plains, the dreadful <WSD>Hiss</WSD> resound. 
Meaning of the word marked with <WSD> tags:  A sibilant sound, such as that made by a snake or escaping steam; an unvoiced fricative.