Four travelers in Greece were murdered by brigands, prompting an "angry outburst of anti-Greek feeling in London".

Though his employers, the Ralli Brothers, told him to remain silent, he researched the incident and wrote a 192-page pamphlet about it[5] which he then delivered to one hundred members of Parliament.

He then had a series of increasingly senior postings in London, Vienna, the Netherlands, and the United States, but was recalled to Athens in 1892.

In 1867, for the Exposition Universelle in Paris, he prepared an exhibit and catalogue raisonné for all of the newspapers and periodicals published in Greece in 1866.

During the period 1874 to 1880, his collecting became more systematic, including not just books, but also drawings and prints on Turkish and Greek life and costume.

In the 1880s, he "formed the 'grand design' that was to dominate his collecting for the rest of his life: to form a library that represented the creative genius of Greece at all periods, the influence of her arts and sciences upon the western world, and the impression created by her natural beauty upon the traveller", with the plan of donating it to the National Library of Greece.

[3] In 1922, he offered his collection of 24,000 volumes to the American School of Classical Studies in Athens.