Improvements in Suspending or Supporting Sonorous Metallic and Non Metallic Discs or Plates.
Year: 1887

page_text: Date of Application, 8th Mar., 1887
Complete Left, 14th Nov., 1887
Complete Accepted, 30th Dec., 1887
PROVISIONAL SPECIFICATION.
Improvements in Suspending or Supporting Sonorous Metallic and
Non Metallic Discs or Plates.
I JOSEPH PRIESTLEY SMITH of No. 21 Broad Street, Birmingham in the County of
Warwick Surgeon do hereby declare the nature of this Invention to be as follows:-
My invention has for its object so to suspend or support sonorous metallic and non
metallic discs or plates that they will when struck at or near their centres give out a
pure long sustained musical sound and my said invention consists in suspending or
supporting the said discs or plates at the points and by the means berein after
described.
My invention is applicable to the suspending or supporting of the said discs or
plates for various purposes such for example as substitutes for gongs and bells as well
as for percussive musical instruments.
I will describe my invention in connection with a circular flat disc of brass.
In suspending the said disc according to my invention I make one two or more
holes in the principal nodal circle of the disc and by means of a cord or cords or a
wire or wires attached to the disc by the holes I suspend the disc in the air. When
the disc so suspended is struck at or near its centre it gives out a pure musical sound
of greater intensity and persistency than the same plate will yield if differently sus-
pended and struck with the same force. The disc may be suspended either in a
vertical or horizontal position. When it is suspended in a vertical position one sus-
pending cord or wire may be employed. I prefer however to employ not less than
two. When the disc is supported in a horizontal position not less than three
suspending cords or wires are by preference employed.
In order to find the diameter of the nodal circle of the disc and the distance from
the centre at which the disc is to be suspended or supported the length of the radius
of the disc is multiplied by the decimal fraction 707 the product is the length of the
radius of the nodal circle.
.

page_text: Although I have only described my invention in connection with a flat disc of brass
that is a disc having parallel sides yet my invention is applicable to the suspending
or supporting of sonorous discs or plates which are not flat and discs or plates the
sides of which are not parallel such for example as discs or plates having circular
corrugations concentric with the centre or having one flat side and the other
corrugated or diminishing in thickness from the centre to the margin or the reverse.
Dated this Eighth day of March 1887.
W. T. WHITEMAN,
Agent for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Suspending or Supporting Sonorous Metallic and
Non-metallic Discs or Plates.
I JOSEPH PRIESTLEY SMITH of No. 21 Broad Street, Birmingham in the County of
Warwick, Surgeon, do hereby declare the nature of my Invention and in what
manner the same is to be performed to be particularly described and ascertained in
and by the following statement :-
My invention has for its object so to suspend or support sonorous metallic and non-
metallic discs or plates that they will when struck at or near their centres give out a
pure long sustained musical sound; and my said invention consists in suspending
or supporting the said dises or plates at the points and by the means herein after
described.
My invention is applicable to the suspending or supporting of the said dises or plates
for various purposes, such for example, as substitutes for gongs and bells as well as
for percussive musical instruments.
I will describe my invention in connection with a circular flat disc of brass or bell
metal.
In suspending the said disc according to my invention I make one, two or more
holes in the principal nodal circle of the disc and by means of a cord or cords or a
wire or wires attached to the disc by the holes I suspend the disc in the air. When
the disc so suspended is struck at or near its centre it gives out a pure musical sound
of greater intensity and persistency than the same plate will yield if differently
suspended and struck with the same force.
The disc may be suspended either in a vertical or horizontal position. When it is
suspended in a vertical position one suspending cord or wire may be employed. I
prefer however to employ not less than two. When the disc is supported in a

page_text: norizontal position not less than three suspending cords or wires are by preference
employed.
In order to find the diameter of the nodal circle of the disc and the distance from
the centre at which the disc is to be suspended or supported the length of the radius
of the disc is multiplied by the decimal fraction 707 the product is the length of the
radius of the nodal circle.
I will now describe with reference to the accompanying Drawing the manner in
which my invention is to be performed.
Figure 1 represents in elevation a sonorous disc or plate having holes h, h made in
the nodal circle k indicated in dotted lines for suspending or supporting the said
disc or plate according to my invention.
Figure 2 represents in elevation a similar disc or plate and illustrates one of the
ways of finding the nodal circle k in which circle the holes h, are made; Figure 3
shows the disc in edge view and illustrates one method of suspending it and Figure 4
represents in edge view the disc suspended in another way.
In order to find the nodal circle let the verticle line a Figure 1. be the diameter of
the disc and the horizontal line b the diameter of the nodal circle, then the ratio of
the line b will be to the line a as 7.07 is to 10 or as 707 is to unity.
In Figure 2 another way of finding the nodal circle is illustrated. Let c be a
radius struck from the centre d of the disc to its periphery e and let be another
radius struck from the centre d of the disc to its periphery e at right angles to
the radius c. Join e, e by the chord g and bisect the chord g. The line joining the
point of bisection of the chord g and the centre d is the radius of the nodal circle k
in which the suspending holes h, h must be made. The area of that portion of the
disc enclosed by the nodal circle is equal to one half the area of the whole disc.
The sonorous discs or plates to be suspended according to my invention may either
be metallic or non-metallic. When metallic discs are employed bell metal is used
preferably and when non-metallic discs are employed glass is used preferably.
Although I have only described my invention in connection with a flat disc of brass
or gun metal, that is, a disc having parallel sides yet my invention is applicable to
the suspending or supporting of sonorous discs or plates which are not flat and discs
or plates the sides of which are not parallel, such for example, as discs or plates
having circular corrugations concentric with the centre or having one flat side and
the other corrugated; or diminishing in thickness from the centre to the margin or the
reverse.
Other things being equal the musical note produced varies in a definite relation to
the diameter and thickness of the disc namely:-
-
With a given thickness a number of vibrations per second varies inversely as the
area of the disc, that is, as the square of its diameter. Thus if we have two discs
of the same thickness the one ten inches diameter, the other five inches diameter,
then the area of the smaller is one fourth the area of the larger and its vibrations are
four times as rapid; the note given by the smaller is therefore two octaves higher
than the note given by the larger.
With a given diameter the number of vibrations per second varies directly as the
thickness of the disc. Thus, if we have two discs equal in diameter the one twice
as thick as the other the vibrations of the thicker are twice as rapid as those of the
thinner the note of the thicker one is one octave higher than that of the thinner. By
means of these rules if we know the note of any given disc we can calculate the
dimensions necessary for a disc which shall give any other note.
To sharpen the note of a disc I place it in the lathe and reduce its diameter more
or less by taking a little off the edge; it may also be sharpened by taking a little off
the surface near the edge.
To flatten the note of a disc I take a little off the surface near to the centre of the
disc. It is best. however to tune the disc by sharpening rather than by flattening the
notes for in the case of bell metal the resonance is impaired when the surface
of the metal is removed. Although no particular ratio between the diameter and

page_text: thickness of the disc suspended according to my invention is necessary yet I prefer
to employ discs the thickness of which is to the diameter about as one to fifty.
The discs may be suspended by means of cords passed through the holes h h and
carried upwards in a divergent manner as represented in Figure 3; or the cords may
be simply knotted on one side of the disc as represented in Figure 4, in the latter
case the plate or dise will hang in a slightly oblique position so that its upper edge
is not in contact with the cord.
Or instead of passing the cord through the holes in the disc small hooks or eyes
or headed pins may be screwed or otherwise fixed in the said holes and the disc
suspended by passing the cord under the hooks or headed pins or through the
said eyes. But I prefer to suspend the disc by the methods represented in the
Drawing.
There may be more than two points of suspension and in this case the discs may
be suspended in a horizontal position but the vertical position is preferable.
The discs are sounded by striking them at or near the centre with a hammer or
mallet the surface of which is padded with leather india rubber or other soft
material. The discs may be employed singly or any number of discs may be arranged
together and they may be conveniently struck by hand in the manner before described
or by mechanism such as is employed in percussive musical instruments.
Although I prefer to employ cords for the suspension of the sonorous discs made
of vegetable or animal fibre such as hemp or silk yet cords of other organic
materials may
be employed such for example as gutta percha and india rubber
or metallic wires may be employed for suspending the discs.
Having now particularly described and ascertained the nature of my invention
and the manner in which the same is to be performed I declare that I claim as
my invention :-
Suspending or supporting sonorous metallic and non metallic discs or plates by
flexible non metallic cords or by metallic wires connected to the disc by being
secured in or passed through holes in the principal nodal circle of the disc substantially
as herein before described and illustrated in the accompanying Drawings.
Dated this Tenth day of November 1887.
JOSEPH PRIESTLEY SMITH.