he following
account of it being given in the _Electrical Review_ of New York, May 3,
1899:

"The island of Bornholm in the Baltic, which consists of a mass of magnetic
iron ore, is much feared by mariners. On being sighted they discontinue
steering by compass, and go instead by lighthouses. Between Bornholm and
the mainland there is also a dangerous bank of rock under water. It is said
that the magnetic influence of this ore bank is so powerful that a balanced
magnetic needle suspended freely in a boat over the bank will take a
vertical position."

[29] PAGE 5, LINE 35. Page 5, line 43. _Josephus Costa._--This is
unquestionably a misprint for _Acosta_ (Joseph de), the Jesuit, whose work
_Historia natural y moral de las Indias_ was publisht at Seville in 1590.
An Italian edition appeared at Venice in 1596. The English edition,
translated by E. Grimestone, _The Naturall and Morall Historie of the East
and West Indies_, was publisht in London in 1604 and 1878. There are in
Gilbert's book references to two writers of the name of Costa or Costaeus,
Joannes Costa of Lodi, who edited Galen and Avicenna (see pp. 3 and 62),
and Filippo Costa of Mantua, who wrote on antidotes and medicaments (see p.
141). The passage to which Gilbert refers is in Acosta's _Historia_ (ed.
1590, p. 64).

"Deziame a mi vn piloto muy diestro Portugues [~q] eran quatro puntos en
todo el orbe, donde se afixaua el aguja con el Norte, y contaualas por sus
nombres, de que no me acuerdo bien. Vno destos es el paraje de la Isla del
Cueruo, en las Terceras, o Islas de Acores, como es cosa y a muy sabida.
Passando di alli a mas altura, Noruestea, que es dezir, [~q] declina al
Poniente ... que me diga la causa desta efecto?... Porque vn poco de hierro
de fregarse c[~o] la piedra Iman ...

"Mejor es, como dize Gregorio Theologo, que a la Fe se sujete la razon,
pues aun en su casa no sabe bien entenderse...."

[30] PAGE 5, LINE 36. Page 5, line 45. _Livius Sanutus._--Livio Sanuto
publisht at Venice in 1588 a folio work, _Geografia distinta in xii Libri;
ne' quali, oltre l'esplicatione di nostri luoghi di Tolomeo, della Bussola
e dell' Aguglia, si dichiarono le provincie ... dell' Africa_. In this work
all Liber i. (pages 1-13) deals with observations of the compass,
mentioning Sebastian Cabot, and other navigators. He gives a map of Africa,
showing the central lakes out of which flow the _Zaires fluvius_ and the
_Zanberes fluvius_.

[31] PAGE 6, LINE 2.