IMPROVEMENTS IN ARMATURES FOR MAGNETO-ELECTRIC AND DYNAMO-ELECTRIC MACHINES AND MOTORS
Year: 1881

page_text: LETTERS PATENT to John Henry Johnson, of 47, Lincoln's Inn Fields, in the
County of Middlesex, Gentleman, for an Invention of "IMPROVEMENTS IN
ARMATURES FOR MAGNETO-ELECTRIC AND DYNAMO-ELECTRIC MACHINES AND
MOTORS." A communication from abroad by William Woodnutt Griscom, of
Philadelphia Pennsylvania United States of America
PROVISIONAL SPECIFICATION left by the said John Henry Johnson at the
Office of the Commissioners of Patents on the 19th December 1881.
JOHN HENRY JOHNSON of 47 Lincoln's Inn Fields in the County of Middlesex
Gentleman "IMPROVEMENTS IN ARMATURES FOR MAGNETO ELECTRIC AND
DYNAMO-ELECTRIC MACHINES AND MOTORS." A communication from abroad by
William Woodnut Griscom of Philadelphia Pennsylvania United States America.
This Invention relating to improvements in armatures for magneto electric and
dynamo electric machines and notors has especial reference to armatures of the
type known as Seimens armatures but is applicable to the poles of all other
magnets or armatures and it consists in dividing the bipolar extremities of such
armatures into two or more sections concentric with each other, one or more of
such sections being at such a distance as to utilize the magnetic lines of force
which fill the space between the two poles of the field magnets whilst the other
section or sections are arranged so as to pass in close proximity to the poles of the
field magnets and thus utilize the powerful attraction between the poles of the
armature and magnet as the one approaches the other.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said John Henry Johnson in the Great Seal Patent Office on the
17th June 1882.
JOHN HENRY JOHNSON of 47 Lincoln's Inn Fields in the County of Middlesex
Gentleman. IMPROVEMENTS IN ARMATURES FOR MAGNETO-ELECTRIC AND
DYNAMO-ELECTRIC MACHINES AND MOTORS." A communication from abroad by
William Woodnutt Griscom of Philadelphia Pennsylvania, United States of
America.
This Invention relating to improvements in armatures for magneto-electric and
dynamo-electric machines and motors has especial reference to armatures of the
type known as Siemens armatures but it is applicable to the poles of all other
magnets or armatures and it consists in dividing the bi-polar extremities of such
armatures into two or more sections concentric with each other one or more of
such sections being at such a distance as to utilise the magnetic lines of force
-which-fill-the-space-between-the-two-poles-of-the-field-magnets-whilst-the-other-
section or sections are arranged so as to pass in close proximity to the poles of
the field magnets and thus utilise the powerful attraction between the poles of the
armature and magnet as the one approaches the other.
And in order that the said Invention may be fully understood I shall now
proceed more particularly to describe the same and for that purpose shall refer to
the several Figures in the annexed Sheet of Drawings the same letters of reference
indicating corresponding parts in both the Figures.
Figures 1 and 2 of the accompanying Drawings represent a transverse section of
a magneto-electric dynamo or electro-magnetic armature and a field magnet
respectively constructed according to the said Invention.
Referring to Figure 1 A is an armature of the before mentioned type having its
bi-polar extremities divided into two or more sections concentric with each
other one or more of such section m revolving or working at such a distance
within the field magnets B and C (see Figure 2) so as to utilise the magnetic lines
of force which are generated and disseminated in the magnetic field or space
between the two poles of the aforesaid magnets.
The other section or sections p before referred to, are longitudinal ribs or pro-
jections concentric with but extending or protruding above or beyond the
peripheries of the other sections m, so as to pass when the armature is revolving,
in closer proximity to the poles of the field magnets B and C than do the said
sections m so as to economically utilise the lines of magnetic force between the
poles of the field magnet. The interior surfaces of the field magnets B and C are
formed or provided with projecting ribs or pieces p₁ arranged so as just to clear
the projections p upon the armature A when it is revolving.
In this manner the poles p p¹ are caused to utilise certain magneto- or electro-
inductive influences upon the extremely close approach of iron to iron, while the
polar surfaces m m¹ are arranged for utilising the induced lines of force extending
across the magnetic field of the magnets B and C.
Having now described and particularly ascertained the nature of the said
Invention and the manner in which the same is or may be used or carried into
effect I would observe in conclusion that what I consider to be novel and original
and therefore claim as the Invention secured to me by the hereinbefore in part
recited Letters Patent is :-
The improvements in armatures for magneto-electric and dynamo-electric

page_text: machines and motors substantially as and for the purpose hereinbefore explained
with reference to the accompanying Drawings.
In witness whereof I the said John Henry Johnson have to this my Speci-
fication set my hand and seal this Twelfth day of June One thousand
eight hundred and eighty two.
J. HENRY JOHNSON. (L.S.)