190 Dr. Faraday’s Experimental Researches in Electricity. 
2645. The extremities of the experimental helix wire were 
connected witha very delicate galvanometer, placed 18 or 20 feet 
from the machine, so as to be unaffected directly by the electro- 
magnet; but a commutator was interposed between them. is 
commutator was moved by the wooden lever (2643.), and as the 
electric currents which would arrive at it from the experimental 
helix, in a complete cycle of motion or to and fro action of the 
metal cylinder (2643.), would consist of two contrary portions, 
et so the office of this commutator Mrs sometimes to take up these 
“portions it succession and send them on in one consistent current 
_ =, to the galvanometer, and at tee chiak to oppose them and to 
4 ~ neutralize their result; and therefore it was made adjustible, so 
ee as to change at any period o the time or part of the motion. 
~~ 2646. With such an arrangement as this, it is known that, 
‘however powerful the magnet, and however delicate the other 
parts of the apparatus, no effect will be produced at the galvan-. 
ometer as long as the magnet does not change in force, or in its 
ae ion upon ueigheores rie or in its distance from, or rela- 
* 
Ree ee 
: 
. Should imagine, indeed, a be ‘alinost the same in principle and 
__srattice as that.of. wo See » — that it gives me 
Ad * contrary results. rig 7 
ch at firsemayseet ee All parts of the apparatus 
ld have perfect stead and be fixed almost with the care 
if ere then 
ete 
. ‘ alt 
“a « 
va ane and thus, without care, _errors m mighty ak 
+e eal ail iei3, results. ‘Therefore ' me 
*.*> machine &c.), th 
Be ter stood*u 5 
ee ste" ta 
~_daid upon’th bs 
ta 
«,” fully strutted, a] 
7 a sa gain 
4 
» sho uld be* 
port 
‘the end of oe ad fro: journ ¥ "bt 
‘should be of hammered brass-br,copper. 
a ct oo It is pbaclte “4 neces eet 
