Sentence:  Seated on the <WSD>platform</WSD> were Amos C. Barstow , ex-mayor of Providence and a wealthy Republican stove manufacturer ; Thomas Davis , an uncompromising Garrisonian ; the Reverend Augustus Woodbury , a Unitarian minister ; the Reverend George T. Day , a Free-Will Baptist ; Daniel w. Vaughan , and William H. H. Clements . 
Meaning of the word marked with <WSD> tags:  a raised horizontal surface