The Greenwich Equipment. Photo by Plaskett.
Further info from a newspaper caption in J.E. Maybee's scrapbook  (p.17):
MR. E. WALTER MAUNDER, F.R.A.S., OPERATING PRINCIPAL INSTRUMENT OF THE GREENWICH OBSERVATORY OUTFIT.
Mr. Maunder, who, with his wife, joined the party on special invitation of Sir Wilfred Laurier, is Superintendent of the solar department at the Royal Observatory, Greenwich, England. The eclipse flag was lowered to half-mast after totality.