ROBERT NORMAN. 211 



Four years after Hartmann's letter was written, one 

 Fortunius Affaitatus, a native of Cremona, addressed a 

 treatise to Pope Paul III in which it has been supposed 

 there is some allusion to the dip. The theory of Affaitatus 

 is interesting in that it opposes the older notion of sym- 

 pathy between pole and needle, and substitutes a sort of 

 inertia inherent to matter and to the magnet in particular, 

 whereby it follows the movement wherever possible of the 

 heavenly sphere. And, as this has the greatest velocity 

 at the equator, and the least at the poles, so the magnet, 

 not being able to find any point of rest, lowers itself at the 

 equator toward the pole; a merely fanciful speculation 

 which obviously has nothing to do with the inclination of 

 the needle, which is under consideration. 1 



The man who gave to the world the first correct knowl- 

 edge and who is most commonly credited with the dis- 

 covery of the dip is Robert Norman, an instrument maker 

 of Bristol, England, who, in 1576, announced his achieve- 

 ment in a little treatise called the "Newe Attractive." 2 

 The conditions are those which we shall find repeated 

 many times in this history a possibly independent in- 

 ventor, realizing the full importance of his accomplish- 

 ment, anticipated, in point of time, by others who, if they 

 perceived the extent of their discovery, left no record to 

 that effect. Peregrinus undoubtedly discovered the incli- 

 nation of the needle to a globular magnet, but not to the 

 earth. Hartmann discovered the inclination of the needle 

 to the earth, but says himself that he cannot understand 

 it, and besides never sees the full extent of the angle of 

 dip. It is not unreasonable to believe that Norman got 

 nothing from Hartmann, for a private letter to a Prussian 

 Duke was not at all likely to come under his notice. But 

 whether, with Hartmann, he drank from the same spring 



1 Affaitatus: Theolog. Phys. et Astron. Considerationes, Venice, 1659. 

 See, also, D'Avezac : Apercus Hist Sur la Boussole. Bull, de la Soc. 

 Ge"og., 1860. Bertelli: Memoria sopra Peregrine, 115. 



2 London, 1581. Reprinted, 1720. 



