In 1891, W.A.B. Coolidge analyzed these ascents and concluded that both parties had reached the 4,618 m Grenzgipfel instead, which is a mere 50 meters to the east of Dunantspitze, an idea adopted by the Alpine historian Gottlieb Studer in 1899. Coolidge transferred the honor of first climbing Dunantspitze to the brothers Christopher, Edmund and James G. Smyth from Great Yarmouth and unnamed guides, who reached it on 1 September 1854, also from the Silbersattel. (The guides were Ulrich Lauener from Lauterbrunnen and Matthias and Johann Zumtaugwald.) Two more parties reached the Ostspitze within two weeks, each time with Zumtaugwald brothers as guides. The 1870 Siegfried Map, current in Coolidge and Studer's time, shows Grenzgipfel to be exactly 7 meters lower than the Ostspitze and Dufourspitze, perhaps helping Coolidge to make his assessment. The real, 14 m height difference (a ~24° instead of 12° angle from Grenzspitze) and the presence of Zumtaugwalds at every ascent suggest a weakness in Coolidge's argument, and modern writers like Pusch, Dumler and Burkhardt assume that the 1848 and 1851 ascendants reached Dunantspitze after all.