IMPROVEMENTS IN THE CONSTRUCTION OF CHAIRS AND FOOTSTOOLS FOR THE USE OF DENTISTS, AND IN CHAIRS, COUCHES, AND BEDS FOR INVALIDS
Year: 1862

page_text: LETTERS PATENT to William Lafferty Boyle, of San Francisco, in the
State of California, one of the United States of North America, but now
residing at Eastbourne Terrace, in the County of Middlesex, Dentist,
for the Invention of "IMPROVEMENTS IN THE CONSTRUCTION OF CHAIRS AND
FOOTSTOOLS FOR THE USE OF DENTISTS, AND IN CHAIRS, COUCHES, AND BEDS
FOR INVALIDS."
Sealed the 10th February 1863, and dated the 13th August 1862.
PROVISIONAL SPECIFICATION left by the said William Lafferty Boyle
at the Office of the Commissioners of Patents, with his Petition, on the
18th August 1862.
I, WILLIAM LAFFERTY BOYLE, of San Francisco, in the State of California,
one of the United States of North America, but now residing at Eastbourne
Terrace, in the County of Middlesex, Dentist, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF CHAIRS AND
FOOTSTOOLS FOR THE USE OF DENTISTS, AND IN CHAIRS, COUCHES, AND BEDS FOR
INVALIDS," to be as follows:-
This Invention of improvements in the construction of chairs and footstools
for the use of dentists, and in chairs, couches, and beds for invalids, relates, in
the first place, to a novel mode of constructing dental chairs and footstools
so that they may be rendered available with facility for the use of persons

page_text: of different stature while undergoing dental operations. This part of the
Invention consists in an improved means of adjusting the parts of the chair
and footstool to suit the required position of the patient, and of altering the
relative position of parts of the chair with great ease, certainty, and rapidity
when required.
In adapting the first part of my Invention to dentists' chairs, I attach the
back to the body of the chair by hinges at or near its lower end, and I
support the back from the arms by means of straps of leather or by chains
at both sides of the chair. These straps or chains are to be fastened to spring
rollers, or to a roller shaft concealed in the back of the chair at about the
middle of its height. Upon this roller shaft is placed a notched or ratchet
wheel with a spring pawl taking into it, so as to hold it in any desired posi-
tion. The outer end of this pawl projects from the back of the chair at some
convenient part, and is so arranged that the pawl must be lifted out of the
ratchet wheel, so that the shaft of the latter may be left free to rotate, in order
to allow the back of the chair to be lowered from a vertical to a horizontal
position; but in moving up the back into a vertical position the pawl will
slide over the ratchet teeth of the wheel as it rotates, and the coiled spring
adapted to the roller or shaft will cause it to rotate and take up the slack in
the chains or straps which support the back of the chair in its inclined
position, and cause it to be wound on the spring roller shaft. The head rest
is also attached to the back of the chair by a hinge or hinges of novel
construction, provided with a spring clutch, whereby the head rest may be
retained in any desired position. This hinge and spring clutch consists of an
axle or bolt passing through both ends of the hinge, and upon one end of
this bolt is a feather, which slides in a groove cut through that part of one
of the hinges which is fastened to the back of the chair, and is caused by
means of a spring coiled around the bolt to enter into one of a number of
notches formed in that part of the hinge which is attached to the head rest,
thus forming a kind of spring clutch, so that when the rest has been placed at
the required inclination it will be securely held there. A lateral movement
may be given to this bolt by pulling a handle attached to one end, so as to
withdraw the feather from the notch, and a spring or springs are provided to
return and keep the several parts in place when the desired inclination of the
rest has been obtained.
The second part of my Invention relates to a system of jointed rods or
levers, together with a screwed shaft with right and left-handed threads or
other mechanical means for working the levers, and thereby raising or lowering
the seat of chairs, couches, or beds in a perfectly vertical line. In adapting

page_text: this part of my Invention to the seat of a chair, I make the seat in the form
of a box to contain the springs usually employed in constructing spring seats.
This box must be of suitable size, and is made to slide up and down within
the framework of the chair. The seat or box is supported by a double set of
levers placed between the sides of the box seat and the frame of the chair
both at the back and front of the chair. These levers are to be attached to
the box seat at their upper ends by stud axles, and at their lower ends to stud
pins on the ends of two travelling bars or screw boxes. Each of these levers
has a radius rod jointed to it at or near the centre of its length, and the lower
ends of these radius rods move upon a fixed stud pin in the frame of the
chair, or on a stud pin upon an extra cross bar at the same horizontal line to
that at which the lower end of the levers are jointed to the travelling bars;
these bars I cause to approach or recede from each other by means of one or
more right and left-handed screws, which pass through the screw boxes to
which they are attached. These right and left-banded screws turn in bearings
at each side of the frame of the chair. The screws which pass through the
travelling bars or screw boxes have a right-hand screw thread for one bar
and a left-hand screw thread for the other bar, and upon being turned by a
handle at the side of the chair will cause the lower end of the levers to
approach or recede from the fixed stud of their several radius rods, and
thereby raise or lower the seat to which the upper ends of the said levers
are attached. By means of this system of jointed levers or parallel motion
I am enabled to raise or lower the seat, while the whole of the mechanism
may be concealed from sight within the body of the chair. It will be obvious
that this arrangement of levers and right and left-handed screws may be
applied for raising the frames of couches and beds.
The third part of my Invention, which relates to foot and other stools,
consists in a simple method of altering their altitude and inclination, to which
end the footstools are composed of two halves of a box of any suitable shape,
but capable of sliding one within the other. A tendency is given to the inner
one to rise by the pressure of springs contained within it whenever the ends
of the spring levers or pawls are withdrawn from a rack or ratchet attached
to the inside of upper half of the box. Cords are attached to these levers or
pawls, and pass through the sides of the box, so that the internal mechanism
can be commanded with facility. I also construct the lid or upper portion of
the box or stool with a rack and spring pawl, so that it may be adjusted to
any inclination required.
In order to place the patient in a convenient position for the operator, and
to enable the latter to get at the mouth of the patient without being forced

page_text: to assume an uncomfortable attitude, as is now the case, I considerably alter
the shape of the upper part or back of the chair, and also the position of the
hinder feet. The top of the back part is made narrower than usual, and
the hinder feet are extended back, so that they shall not be in the way of the
feet or legs of the operator.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Lafferty Boyle in the Great Seal Patent Office
on the 18th February 1863.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
LAFFERTY BOYLE, of San Francisco, in the State of California, one of the
United States of America, but now residing at Eastbourne Terrace, in the
County of Middlesex, Dentist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirteenth day of August, in the year of our
Lord One thousand eight hundred and sixty-two, in the twenty-sixth year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said William Lafferty Boyle, Her special license, that I, the
said William Lafferty Boyle, my executors, administrators, and assigns, or
such others as I, the said William Lafferty Boyle, my executors, adminis-
trators, and assigns, should at any time agree with, and no others, from time
to time and at all times thereafter during the term therein expressed, should
and lawfully might make, use, exercise, and vend, within the United Kingdom
of Great Britain and Ireland, the Channel Islands, and Isle of Man, an
Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF CHAIRS AND FOOTSTOOLS
FOR THE USE OF DENTISTS, AND IN CHAIRS, COUCHES, AND BEDS FOR INVALIDS,'
upon the condition (amongst others) that I, the said William Lafferty Boyle,
by an instrument in writing under my hand and seal, should particularly
describe and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately after the
date of the said Letters Patent.
"
NOW KNOW YE, that I, the said William Lafferty Boyle, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and by
the following statement, reference being had to the Drawings hereunto
annexed, and to the letters and figures marked thereon (that is to say):-
This Invention of "Improvements in the Construction of Chairs and Foot-

page_text: stools for the Use of Dentists, and in Chairs, Couches, and Beds for Invalids,"
relates, in the first place, to a novel mode of constructing dental chairs and
footstools so that they may be rendered available with facility for the use of
persons of different stature while undergoing dental operations. This part
of the Invention consists in an improved means of enabling the parts of the
chair and footstool to be adjusted to suit the required position of the patient,
and altering the relative position of the parts of the chair with great ease,
certainty, and rapidity when required.
In adapting the first part of my Invention to dentists' chairs, I attach the
back to the body of the chair by hinges at or near its lower end, and I connect
the back to the arms by means of straps of leather or by chains at both sides
of the chair. These straps or chains are to be fastened by one of their ends
to the arms of the chair, and by their other ends to spring rollers or to a roller
shaft concealed in the back of the chair at about the middle of its height.
Upon this roller shaft is placed a notched or ratchet wheel with a spring pawl
taking into it, so as to hold it in any desired position. The head rest is also
attached to the back of the chair by a hinge or hinges of novel construction,
provided with a spring catch, whereby the head rest may be retained in any
desired position.
The second part of my Invention relates to a system of jointed rods or
levers, together with a screwed shaft with right and left-handed threads or
other mechanical means for working the levers, and thereby raising or lowering
the seat of chairs or the frames of couches or beds in a perfectly vertical line.
This arrangement of levers and right and left-handed screws may also be
applied for raising the frames of couches and beds for the use of invalids.
The third part of my Invention relates to footstools, and consists in a simple
method of altering their altitude and inclination, to which end the footstools
are composed of two halves of a box of any suitable shape, but capable of
sliding one within the other. A tendency is given to the inner one to rise by
the pressure of springs contained within it whenever the ends of certain spring
levers or pawls are withdrawn from a rack or ratchet attached to the inside of
the upper half of the box.
In order to place the patient in a convenient position for the operator, and
to enable the latter to get at the mouth of the patient without being forced to
assume an uncomfortable attitude, as is now the case, 1 considerably alter the
shape of the upper part or back of the chair, and also the position of the
hinder feet, as will be seen on reference to the accompanying Drawings, in
which I have shewn various views of one of my improved dental chairs and
footstools, and the construction of the principal working parts.

page_text: Fig. 1 is a side view of the chair, shewing the back in two positions ;
Fig. 2 is a back view of the same; Fig. 3 is a transverse sectional view,
shewing the arrangement of levers and screws for raising and lowering the
seat.
a, a, is the frame of the chair, to which the back 6 is attached by hinges c, c,
of the ordinary construction; d, d, are chains or straps, (shewn by dots in
Figures 1 and 2,) secured at one end to the arms e, e, of the chair, and by the
other end to a roller shaft f (see Fig. 2) extending across the framework
forming the back of the chair, and turning in bearings fixed to each upright
of the back of the chair. The roller shaft f has a helical spring 9 (Fig. 2)
coiled around it and attached thereto, in the manner common to all spring
rollers. When the back 6 of the chair is moved up towards a vertical position
the spring g will cause the roller shaft f to revolve in its bearings and roll up
the straps d, d. h (Fig. 2) is a ratchet wheel made fast upon the shaft f, and
i is a spring pawl, which takes into the teeth of the ratchet wheel h, and
having its outer end projecting from the back of the chair, as shewn at Fig. 1.
On being depressed the pawl i will be lifted from the ratchet h, and the
back 6 of the chair will be allowed to fall to the desired inclination, a sufficient
amount of the straps d, d, being withdrawn from the roller f to support it at
the desired distance from the arms of the chair. The head rest j is attached to
the back 6 of the chair by the two hinges k, k¹, through which a bolt or axle l,
Fig. 2, passes. A feather m upon one end of the axle slides through a
groove or notch cut in the upper half of the hinge k, which is screwed to the
head restj (this half of the hinge k is notched, as seen best in side view at
Fig. 4). In the lower half of the hinge k are cut a number of notches
(seen in end view, Fig. 5), into one of these the feather m on the axle enters,
and is retained there by a spring n coiled round the axle 1, and which is
compressed between the hinge k and a pin upon the axle. The axle bis
carried through the hinge k', and has an adjustable screw button by which
the amount of lateral motion communicated to it by means of the handle (at
the opposite end) can be determined. This lateral motion is for the purpose
of withdrawing the feather m from one of the notches in that half of the
hinge (shewn in side view, Fig. 5), so as to admit of the head restj being
again adjusted at a different inclination, and on the handle being released the
spring will cause the return of the axle l, and the feather m will enter
another of the notches that may have been brought opposite to it, and will
hold the rest firmly in the position desired.
The second part of my Invention is shewn in sectional front view at Fig. 3.
o is the seat of the chair constructed to slide easily within the frame a, and is

page_text: carried at front and back by levers p, p, attached to the box seat o by stud
pins q, q', and at their opposite ends to stud pins r, r. On the cross bars s, s¹,
t, t¹, are radius rods, jointed at one end to the levers p, p, at about their
centre, and at their other end to stud pins u, u¹, in the ends of the cross
bars v, v¹; or these stud pins u, u', may be fixed in the frame a of the chair.
w is a screw shaft, turning in bearings attached to the frame a; one half of this
shaft has a right and the other a left-handed thread cut thereon, working in
female screw nuts attached to or formed in the cross bars s, s¹. The cross
bars v, v', have holes cut for the free passage of the screw w through them,
and these bars are supported underneath by the angle iron a attached to the
frame of the chair. On turning the screw. shaft w by the handle y, the
bars s, s', will be caused to recede from each other, thus forcing the levers
p, p¹, into a nearly vertical position, as shown by dots in Fig. 3, carrying with
them the seat o, to which they are attached. By this system of jointed levers
it will be seen that the seat will be caused to rise or fall in a perfectly vertical
line.
.
At Fig. 6. I have shewn a spittoon and frame, which I propose in some
cases to adapt to dentists' chairs. A is a bracket, turning in bearings, in-
tended to be screwed to the arms and side framings of the chair, and carrying
at its end the spittoon B, which is fitted with a flexible india-rubber pipe C,
for the purpose of conducting the saliva into a receptacle which may be placed
under the seat of the chair. The bracket A may be made with one or more
hinges, as shewn at z, in order to fold it up, or to enable it to be placed in
the most convenient position.
Figures 7 and 8 are cross and longitudinal sections of a footstool. a and b.
are two halves of a box sliding one within the other; the upper one 6 has hinged
to it a cover b', which can be raised to any inclination desired, and held there
by the spring catch c and rack d. The height of the footstool can be adjusted
by pulling the corde which is attached to the levers f, whose fulcrums are
carried by brackets from the inside of the box b. The lower end of these
levers take into the racks g, fast on the inside of the lower box a, and when
their lower ends are withdrawn from the racks 9 by the cords e the springs h
will cause the box 6 to rise to the desired height, where the several parts will
be retained by allowing the lower ends of the levers f to enter into other
notches in the fixed racks g. It will be evident that a similar arrangement of
levers and screwed shafts, or other equivalent mechanical contrivances, may be
employed to raise the frames of couches or invalid beds in a perfectly vertical
direction.
In order to enable the operator to get closer to the patient, and in a more

page_text: convenient position than usual, the upper part of the back of the chair is cut
away as shewn in Figures 2 and 3, and in order to remove the back legs of
the chair out of the way of the feet of the operator, they are curved back as
shewn in Fig. 1 of the framing, so as to give great freedom to the operator.
Having now described my Invention of "Improvements in the Construction 5
of Chairs and Footstools for the Use of Dentists, and in Chairs, Couches, and
Beds for Invalids, and having explained the manner of carrying the same into
effect, I claim as my Invention,-
First, the mode herein set forth of constructing the fixed parts.
I also claim the use of the spring roller arrangement, shown in Figures 1
1 and 2, for securing the back of the chair at any desired position or incli-
nation.
I further claim the mode shewn of securing the head rest at any incli-
nation.
I also claim the arrangement of levers and screwed shafts, shown in Fig. 3, 1
for raising and lowering the seat of the chair in a vertical direction.
I claim the right of applying a similar mechanical arrangement for raising
the framework of couches and invalid beds.
Lastly, I claim the mechanical footstool shown in Figures 7 and 8.
In witness whereof, I, the said William Lafferty Boyle, have hereunto 2
set my hand and seal, the Eleventh day of February, in the year of
our Lord One thousand eight hundred and sixty-three.
⚫ WM. L. BOYLE. (L.S.)