Bessard (_op. citat._, pages 22 and 48) gives cuts of compasses showing the needle displaced one rumbe to the East.
Gallucci, in his _Ratio fabricandi horaria mobilia et permanentia cum magnetica acu_ (Venet., 1596), describes the needle as inclined 10 degrees from the south toward the south-west.
The frontispiece of the work of Pedro Nuñez, _Instrumenta Artis Navigandi_, Basil., 1592, depicts a compass with the lily set one point to the east.
Reibelt, _De Physicis et Pragmaticis Magnetis Mysteriis_ (Herbipolis, 1731), depicts the compass with the needle set about 12 degrees to the East of North. See also Fournier, _Hydrographie_ (Paris 1667); De Lanis, _Magisterium Natvræ et Artis_ (Brixiæ, 1684); Milliet Deschales, _Cursus seu Mundus { 59} Mathematicus_ (Lugd., 1674). Both the latter works give pictures of the compass-cards as used in South Europe, and in North Europe, and of the various known shapes of needles.
[227] PAGE 168, LINE 29. Page 168, line 33. _Directio igitur inualidior est propè polos._ Here as in many passages _direction_ means _the force which directs_. A similar usage prevails with the nouns _variation_ and _declination_, meaning frequently the force causing variation or declination respectively.
PAGE 172, LINE 13. _perquirere._ The edition of 1633 reads _perquirero_, in error.
[228] PAGE 172, LINE 29. Page 172, line 33. _Ad pyxidis nauticæ veræ & meridionalis formam ... fiat instrumentum._--An excellent form of portable meridian compass, provided with sights for taking astronomical observations, is described by Barlowe (_The Navigators Supply_, London, 1597), and is depicted in an etched engraving. An identical engraving is repeated in Dudley's _Arcano del Mare_ (Firenze, 1646). Gilbert's new instrument was considerably larger.
[229] PAGE 174, LINE 19. Page 174, line 21. _addendo vel detrahendo prostaphæresin._--"Prosthaphæresis, conflata dictione, ex additione et subtractione speciebus logistices, nomen habet ab officio, quia vt in semicirculo altero ad æquabilem motum adijcitur, ita in altero subtrahitur, vt adparens motus ex æquabili taxetur: atque hinc fit, quòd quæ Prosthaphæresis dicitur Ptolemæo, ea vulgò æquatio vocetur." (Stadius, _Tabulæ Bergenses_, Colon. Agripp., 1560, p. 37.)