IMPROVEMENTS IN DYNAMO MAGNETIC ELECTRIC MACHINES AND IN MAGNETS TO BE USED IN SUCH MACHINES AND FOR OTHER PURPOSES."
Year: 1882

page_text: LETTERS PATENT to Thomas Donnithorne of Gracechurch Street in the City
of London for an Invention of "IMPROVEMENTS IN DYNAMO MAGNETIC
ELECTRIC MACHINES AND IN MAGNETS TO BE USED IN SUCH MACHINES AND
FOR OTHER PURPOSES."
PROVISIONAL SPECIFICATION left by the said Thomas Donnithorne at the
Office of the Commissioners of Patents on the 6th September 1882.
THOMAS DONNITHORNE of Gracechurch Street in the City of London
"
IMPROVE-
MENTS IN DYNAMO MAGNETIC ELECTRIC MACHINES AND IN MAGNETS TO BE USED
IN SUCH MACHINES AND FOR OTHER PURPOSES."
""
This Invention has for its object improvements in dynamo magnetic electric
machines and in magnets to be used in such machines and for other purposes.
At present magnets for dynamo electric machines are for the most part made of
or founded upon a solid piece of more or less soft iron.
I make magnets of a tube of soft iron with an open mouth at one end.
I fill this tube with magnetic iron ore (magnetic oxide of iron) in a granulated
or crystalline form and stop the mouth of the tube with a stopper of the same
soft iron.
In constructing a dynamo magnetic electric machine I range in circle a number
of permanent magnets made in the above manner, or else a number of solid
permanent magnets made in ordinary ways-I range the magnets in a circle with
the north pole of one magnet towards the south pole of the next magnet and so on
for all the magnets in the circle. I carry the circle of magnets upon a circular
frame composed of two standards each forming a half circle or approximately so.
I place two of such circles of magnets concentrically one on each side of a wheel
so that such wheel may revolve between them.
The exterior of the periphery of the wheel I make slightly less in circumference
than the exterior of the circular frame which carries the magnets whilst the inner

page_text: circumference of the periphery of the wheel I make about the same as the inner
line of the circle of magnets.
The periphery of the wheel I make partly of brass or other suitable material
and partly of iron in alternate lengths. As many lengths of soft iron are used in
the circumference of the wheel as there are spaces between the magnets in the
circles of magnets. The iron parts are solid pieces of soft iron and they are held
together by intermediate pieces of brass which are parts of the spokes of the wheel.
Magnets formed as herein before described may be used in other constructions of
dynamo machines and for other purposes for which permanent electro magnets are
or may be used.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Thomas Donnithorne in the Great Seal Patent Office on the
5th March 1883.
THOMAS DONNITHORNE of Gracechurch Street in the City of London "IMPROVE-
MENTS IN DYNAMO MAGNETIC ELECTRIC MACHINES AND IN MAGNETS TO BE USED
IN SUCH MACHINES AND FOR OTHER PURPOSES
"
This Invention has for its object improvements in Dynamo Magnetic Electric
Machines and in Magnets to be used in such Machines and for other purposes
I make Magnets of a tube of soft iron with an open Mouth at one end
I fill this tube with Magnetic Iron Ore (Magnetic oxide of Iron) and stop the
Mouth of the tube with a stopper of the same soft Iron
In constructing a Dynamo Electric Machine I arrange in a circle a number of
permanent Magnets made in the above manner or else a number of solid permanent
Magnets made in ordinary ways
I range the Magnets in a circle with the North pole of one Magnet towards
the South pole of the next Magnet and so on for all the Magnets in a circle
I carry the circle of Magnets upon a circular frame composed of two Standards
each forming a half circle or approximately so
I place two of such circles of Magnets one on each side of a Wheel so that such
wheel may revolve between them
In carrying the Invention into practical effect I proceed as follows
I prepare a series of tubes of soft Iron closed at one end with a soft Iron plug
and I pack these tubes full of Magnetic oxide of Iron preferably in a granulated or
crystalline form and after carefully filling the tube I insert a soft iron stopper
which by preference projects slightly to form the external pole if the Magnet
I use these Magnets in constructing dynamo Magnetic electric Machines and for
various other purposes
When I use these Magnets for a dynamo Magnetic electric Machine I arrange a
number of permanent Magnets made in the above manner as follows
I take Four semicircular plates each of which is affixed to a standard or
standards in such a way that when they are affixed to a bed plate two of the semi-
circles shall face the other two semicircles
I affix a number of my Magnets to the opposing faces of these plates in such a
manner that their length is in the line of the axis of the semicircles
I arrange the polarity of these Magnets so that in each semicircle the external
pole or that which faces towards the opposing two semicircles shall be alternately
a North and a South pole
I affix these semicircles and magnets in such a way that they cannot move
Between these Four semicircles which correspond to two circles with two
notches or gaps cut out of each circle I place a composite wheel of Iron and Brass
capable of rotation and suitably connected with Machinery to cause it to rotate so
that such Wheel may revolve at any desired speed between the opposing poles of
the Magnets hereinbefore referred to and in very close proximity to them
The exterior of the periphery of the Wheel I make slightly less in circumference
than the exterior of the circular frame which carries the magnets whilst the inner
circumference of the periphery of the Wheel I make about the same as the inner
line of the circle of Magnets
The periphery of the Wheel I make partly of Brass or other suitable material
and partly of Iron in alternate lengths

page_text: As many lengths of soft Iron are used in the circumference of the wheel as there
are spaces between the Magnets in the circles of Magnets
The Iron parts are solid pieces of soft Iron and they are held together by
intermediate pieces of Brass which are parts of the spokes of the Wheel
Magnets formed as hereinbefore described may be used in other constructions of
dynamo Machines and for other purposes for which permanent electro Magnets are
or may be used
In witness whereof I the said Thomas Donnithorne have hereunto set my
hand and seal this Fifth day of March One thousand eight hundred and
eighty three
THOS DONNITHORNE (L.S.)