I found the photo below at Ancestry.com, courtesy of Karen (Titus) Harrison. She identifies the people as Walter Plumb (I believe he is also at far left in the photo above), Eleanor Plumb, Frank R. Smart, and Bertha (York) Plumb.

Mahlon Joab and Ellen Smart Plumb and family. My husband's grandfather, Robert Plumb, is the young boy in the center. (About 1899)

Mahlon Joab, Ellen, and Milton Carlyle Plumb, circa 1882

Ellen Smart Plumb in Back