xii Proceedings of Royal Society of Edinburgh. 
was possible.” But a few years after the last of the Expedition 
Beports was published his health broke down, and he never quite 
recovered his former strength. Henceforward, he was subject to 
the severest limitations as regards work and mental labour ; but by 
avoiding excitement and husbanding his strength, he was enabled 
to accomplish a wonderful amount of scientific work. Thus, in 
1862, he issued his Manual of Geology , in 1864 his Text- Book of 
Geology , and in 1868 the fifth edition of the System of Mineralogy 
— his last and most important contribution to that department of 
science. Notwithstanding all his care, the preparation of this 
great work proved too much for his strength — his health again 
gave way, and was only slowly restored. With advancing recovery, 
he gradually resumed his course of quiet labour — doing much 
work in the field as a geologist, attending to the duties of his chair, 
and writing a number of important papers and books. New 
editions of his Manual of Geology appeared in 1874 and 1880, 
and of the Text-Book of Geology in 1874 and 1883. He also 
found time to write a new work entitled Corals and, Coral Islands 
(1872), and yet another geological volume — The Geological Story 
briefly Told (1875). 
Dana had so far regained strength in 1887 that he was tempted 
to take a long journey. The accounts of an eruption of Kilauea 
in the Sandwich Islands had greatly interested him, and he deter- 
mined to revisit that region, the acquaintance of which he had 
first made in 1840. Accordingly, he set out with his wife and 
youngest daughter, and the result was all that he or his friends 
could desire. He greatly enjoyed himself, every incident of the 
visit, his son tells us, being entered into with the enthusiasm of a 
mind which years could not make old. On his return he wrote a 
number of papers descriptive of what he had seen, and in the 
winter of 1889-90 prepared his work on Volcanoes, which, along 
with a new edition of Corals and Coral Islands , appeared early in 
1890 — the prefaces of both books being dated on his 78th birth- 
day. In the autumn of the same year, however, his health once 
more gave way, and for several months his busy pen was laid aside. 
But he could not long endure complete rest ; and, by-and-by, was 
able to dictate a small work dealing with the geology of the New 
Haven district, which was issued in 1891. His duties as professor 
