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THE 



PHILOSOPHICAL MAGAZINE, 



DECEMBER 1800. 



I. A fljort View of the new Elcclric Experiments performed 

 by Dr. Van Marum. 



JL HE experiments which form the iubject of this article 

 Were performed with the large machine in the Teylerian mu- 

 faeum at Haarlem, partly undertaken at the requeft of other 

 phHofophers, and deferibed in his laft work on electricity, 

 entitled Tw'eede Vcrvolg der Proefneem'ingen geclaan met 

 Teey let's El. Much. Haarlem 179,5, 4-to. It muft here be 

 bbferved that, fince the laft publication refpectirig thefe ex- 

 periments, great improvements have been made in the large 

 machine, and particularly in regard to the cufhions. Ac- 

 cording to the old mode of eonftruction, the cufhions were 

 prcfled towards the glafs plates by means of two fcrews, in 

 confequence of which it was not poflible to maintain an 

 uniform preflure on both fides. At prefent, however, an 

 uniformity of preflure is obtained by two fteel fprings, which 

 arc applied with hinges to the end of two iron plateg, and are 

 kept together bv one fiugle fcrew. As thefe fprings exercife 

 their preflure on the centre of gravity of the cuftiions, the 

 preflure is uniformly the fame in every part. Befides this 

 improvement, the conductor is conftructed fax fuch a manner 

 that, merery by turning, it can be employed fometimes for 

 deceiving pofitive and fometimes negative electricity; fo that 

 both thefe kinds of electricity can be communicated to the 

 conductor by changing its pofition. The collector is no 

 Vol. VllK C c fongct 





