J. Nicklés on Magnetisation. 99 
Art. XI.— Researches in Magneltisation ; by M. Jerome Nicxxis. 
N two memoirs, published in the numbers of this Journal for 
January and March, 1853, treating of the elongation of magnet- 
ised bars and of the influence this elongation sca on the at- 
tracting force, 1 have admitted that the attraction will increase 
with the distance that se 
changed, we vary the distance between the olar branches of a 
bifureate electromagnet. For, on increasing this distance, the 
mass of the iron of which the electromagnet consists is increased, 
or, What is the same, the polar brane es are elongated, which 
Occasions a tendency to augmentation of force; the chances of 
heutralisation between the two poles are diminished, whence re- 
sults another tendency to increase of force. og eee 
is €asily seen that the two tendencies are not of. the.same 
armature is altered: for it is evident that the armature inter- 
cepts more magnetic rays when the poles are remote than when 
they are very near. eer rs: 
n the course of my researches on circular electromagnets, I 
have often verified this conclusion, and as the laws of these elec- 
tromagnets are the same as those which govern bifurcate electro- 
Magnets, it may be seen that the separation of the will also 
have some effect on the power of these magnets. All phyicists 
are not of this opinion, and M. Dub besides others has just pro- 
nounced formally the contrary opinion, as a result of experiments 
Whose precision I do not intend to quests. °C 9 e4 
he facts which I have made known, while they do not con- 
tradict the results of his observations, weaken the force of his 
conclusions. To test it most satisfactorily, I operated, as he, 
with bifurcate electromagnets. ‘The apparatus employed was a 
* And not only in electromagnets which are wound with wire through all their 
length, 28 M. Dub observes in. Poggendorf’s Annalen, wol. xc, The samme error is 
_ Contained in the Jahresbericht of Liebig, &c., 1853, p. 248, ‘ 
., 
ap us 
