279 



SECTION 9. MAGNETISM. 



WEST GALLERY, GROUND FLOOR, ROOM F. 



I. NATURAL MAGNETS. 



Natural Magnet, mounted by Galileo, weighing six 

 ounces. He presented it to the Grand Duke Ferdinand II. del 

 Medici. It is made in the shape of an urn and holds a weight of ten 

 pounds. The Royal Institute of " Studii Supcriori" Florence. 



Galileo was the first to arm natural magnets, and thus succeeded in making 

 them bear very much greater weights ; he proved, at the same time, that 

 the same loadstone can bear a greater weight when in several pieces than 

 when it is in one block ; and that moreover its attractive power can be in- 

 creased by loading it by degrees with an increasing weight. 



Natural Magnet, armed by the Accademia del Cimento. 



Accademia del Cimento. 



The members of the Accademia del Cimento found that the poAver of this 

 magnet was not lost by passing through very many substances ; and that its 

 attractive force varied according to its position with regard to the poles of the 

 earth. 



1106. Great Natural Magnet; one of the largest known. 

 See Lamont, " Handbuch des Magnetismus," 1867, p. 107. 



Teyler Foundation, Haarlem. 



Weight, with the armature - 152 kilograms. 



Force - K P i 114 



1107. Natural Magnet, mounted in brass case, with steel 

 poles, and soft iron keeper. Elliott Brothers. 



llO7a. Natural Loadstones (two), Russian, in perforated 

 and painted metal cases. Bennet Woodcroft, F.R.S. 



II. PERMANENT ARTIFICIAL MAGNETS. 



11O8. Collection of Artificial Magnets, lately forged by 

 M. Van Wetteren, and magnetised at Teyler's Museum. 



Teyler Foundation, Haarlem. 



A. Single magnet, weight 2 '17 kilogr. ; greatest original force, 51 '3 

 kilogr. ; permanent force, 35 9 kilogr. 



