er the title: _Discours fait en une celebre assemblee par le chevalier
Digby .... touchant la guerison de playes par la poudre de sympathie_. The
London edition referred to by De Morgan also came out in 1658, and several
editions followed it in England, France and Germany. But Nathaniel Highmore
in his _History of Generation_ (1651) referred to the concoction as
"Talbot's Powder" some years before Digby took it up. The basis seems to
have been vitriol, and it was claimed that it would heal a wound by simply
being applied to a bandage taken from it.

[192] This work by Thomas Birch (1705-1766) came out in 1756-57. Birch was
a voluminous writer on English history. He was a friend of Dr. Johnson and
of Walpole, and he wrote a life of Robert Boyle.

[193] We know so much about John Evelyn (1620-1706) through the diary which
he began at the age of eleven, that we forget his works on navigation and
architecture.

[194] I suppose this was the seventh Earl of Shrewsbury (1553-1616).

[195] This is interesting in view of the modern aseptic practice of surgery
and the antiseptic treatment of wounds inaugurated by the late Lord Lister.

[196] Perhaps De Morgan had not heard the _bon mot_ of Dr. Holmes: "I
firmly believe that if the whole _materia medica_ could be sunk to the
bottom of the sea, it would be all the better for mankind and all the worse
for the fishes."

[197] The full title is worth giving, because it shows the mathematical
interests of Hobbes, and the nature of the six dialogues: _Examinatio et
emendatio mathematicae hodiernae qualis explicatur in libris Johannis
Wallisii geometriae professoris Saviliani in Academia Oxoniensi: distributa
in sex dialogos (1. De mathematicae origine ...; 2. De principiis traditis
ab Euclide; 3. De demonstratione operationum arithmeticarum ...; 4. De
rationibus; 5. De angula contactus, de sectionibus coni, et arithmetica
infinitorum; 6. Dimensio circuli tribus methodis demonstrata ... item
cycloidis verae descriptio et proprietates aliquot.)_ Londini, 1660 (not
1666). For a full discussion of the controversy over the circle, see George
Croom Robertson's biography of Hobbes in the eleventh edition of the
_Encyclopaedia Britannica_.

[198] This is his _Animadversions upon Mr. Hobbes' late book De principiis
et ratiocinatione geometrarum_, 1666, or his _Hobbianae quadraturae
circuli, cubationis sphaerae et duplicationis cubi confutatio_, also of
1669.

[199] This is the work of 16