108 NOTICES OF THE MEETINGS [Jan. 23, 
have these axes adjusted perpendicular to the line of dip and then 
be revolved. A commutator was employed and associated, both 
with the galvanometer and the parallelograms, so that the upper 
part of the revolving wire always sent the current induced in it 
in the same direction. Here it was found that rotation in one 
direction gave one electric current; that rotation in the reverse 
direction gave the contrary current; that the effect at the gal- 
vanometer was proportionate to the number of rotations with the 
same rectangle ; that with different sized rectangles of the same wire 
the effect was proportionate to the area of the rectangle, 7. e. the num- 
ber of curves intersected, &c. &c. The vicinity of other magnets 
to this magnet made no difference in the effect provided they 
were not moved during the experiments; and in this manner the 
non-interference of such magnets with that under investigation was 
fully established. 
All these and other results are more fully stated and proved in 
papers now before the Royal Society. The general conclusions are, 
that the magnetic lines of force may be easily recognized and taken 
account of by the moving wire, both as to direction and intensity, 
within metals, iron or magnets, as well as in the space around; and 
that the wire sums up the action of many lines in one result : That 
the lines of force well represent the nature, condition, direction, and 
amount of*the magnetic forces: That the effect is directly as the 
number of lines of force intersected, whether the intersection be 
direct or oblique: That in a field of equal force, it is directly as the 
velocity ; or as the length of the moving wire; or as the mass of 
the wire: That the external power of an unchangeable magnet is 
definite yet illimitable in extent ; and that any section of all the lines 
of force is equal to any other section: That the lines of force within 
the magnet are equal to those without: and that they are con- 
tinuous with those without, the lines of force being closed curves. 
[M.F.] 
In the Library, were exhibited :— 
Portrait of Shakspeare (fac-simile in all but colour of the remains 
of a Portrait on Panel by his partner, Richard Burbage, 1597). 
[Presented by W. Nicol, Esq. M.R.I.] 
Whitworth’s Surfaces : —i:e. Two Iron Plates, the surfaces made 
so true by scraping, not grinding, that when one is placed on the 
other, they will not touch until the film of air between them 
becomes displaced by the weight of the upper plate. [Exhibited 
by Mr. J. G. Appold:] 
Model of Appold’s Centrifugal Pump. [Exhibited by Messrs. Watkins 
and Hiill.] 
Hodges’ Power-Accumulators. [Exhibited by Mr. Hodges. ] 
