in a great degree his command of mathematics, and sometimes spoke of
mathematics as nothing more than a system of order carried to a
considerable extent. In everything he was methodical and orderly, and
he had the greatest dread of disorder creeping into the routine work
of the Observatory, even in the smallest matters. As an example, he
spent a whole afternoon in writing the word "Empty" on large cards, to
be nailed upon a great number of empty packing boxes, because he
noticed a little confusion arising from their getting mixed with other
boxes containing different articles; and an assistant could not be
spared for this work without withdrawing him from his appointed
duties. His arrangement of the Observatory correspondence was
excellent and elaborate: probably no papers are more easy of reference
than those arranged on his system. His strict habits of order made him
insist very much upon detail in his business with others, and the
rigid discipline arising out of his system of order made his rule
irksome to such of his subordinates as did not conform readily to it:
but the efficiency of the Observatory unquestionably depended mainly
upon it. As his powers failed with age the ruling passion for order
assumed a greater prominence; and in his last days he seemed to be
more anxious to put letters which he received into their proper place
for reference than even to master their contents.

His nature was eminently practical, and any subject which had a
distinctly practical object, and could be advanced by mathematical
investigation, possessed interest for him. And his dislike of mere
theoretical problems and investigations was proportionately great. He
was continually at war with some of the resident Cambridge
mathematicians on this subject. Year after year he criticised the
Senate House Papers and the Smith's Prize Papers question by question
very severely: and conducted an interesting and acrimonious private