280 SEC. 9. MAGNETISM. 



B. Compound magnet. No. 3,053. Weight, 1 52 kilogr. ; greatest original 

 force, 36*4 kilogr. ; permanent force, 27*7 kilogr. 



C. Two single magnets. No. 3,003. Weight, 0-51 kilogr.; greatest 

 primitive force, 19 '5 kilogr.; permanent force, 12 '4 kilogr. No. 3,005. 

 Weight, 0-52 kilogr.; greatest" original force, 18 '6 kilogr.; permanent 

 force, 13-7 kilogr. 



A third open keeper with movable side plates. 



The box, C, forms a school apparatus, to demonstrate the effect of mutual 

 contact of the magnets, and of the constitution of the keeper, on the distribution 

 of free magnetism, on the weight that can be suspended, and on the deflections 

 of the needle produced by the magnet when open, and when more or less 

 closed. 



See the memoir of Prof. Van der Willigen, Avhich will soon appear in the 

 Archives du Musee Teyler. 



1109. Great Artificial Magnet, forged and magnetised in 

 1850 by Messrs. Van Wetteren and Logemann, according to the 

 directions of Dr. Elias, whose property it is. 



Teyler Foundation , Haarlem. 



Newly magnetised at Teyler's Museum. 



Weight - 28 kilograms. 



Original force " - - 260 



Permanent force - - 200 ,, 



1109a. Large Artificial Magnet made of thin Plates. 



M. Jamin^ Paris. 



10 1O. Photograph of a Horse-shoe Magnet, made by 

 Johann Dietrich, of Basle, in I75o. 



Prof. Hagenbach-Bisclioff, Director, The Physical Insti- 

 tute in the Bernoullianum, Basic. 



1111. Permanent Bar Magnets (pair of), in case. 



James Hoiv fy Co. 



1112. Compound Horse-shoe Magnet. James How $ Co. 



1112a. Series of Permanent Magnets, bar form, in 

 wooden cases for students. Harvey, Reynolds, and Co. 



1113. Logemann's " Magnet, being a powerful battery 

 of steel-plate magnets. Frederick Guthrie. 



11 13 a. Magnets by M. Jamin. M. Breguet, Paris. 



1113b. Magnet, Jamin's, with plates 0'05 m. in width. 



M. Breguet, Paris. 



1113c. Large Artificial Magnet, and fittings. 



M. Jamin, Paris. 



