IMPROVEMENTS IN THE CONSTRUCTION OF 'DIGITORIUMS,' SUCH IMPROVEMENTS BEING APPLICABLE TO PIANOS, ORGANS, AND SIMILAR INSTRUMENTS.” PROVISIONAL SPECIFICATION
Year: 1880

page_text: LETTERS PATENT to William Lowe and Thomas Henry Lowe, of Barnsbury, in
the County of Middlesex, Manufacturers, for an Invention of "IMPROVEMENTS
IN THE CONSTRUCTION OF 'DIGITORIUMS,' SUCH IMPROVEMENTS BEING
APPLICABLE TO PIANOS, ORGANS, AND SIMILAR INSTRUMENTS.”
PROVISIONAL SPECIFICATION left by the said William Lowe and Thomas
Henry Lowe at the Office of the Commissioners of Patents on the 23rd
August 1880.
WILLIAM LOWE and THOMAS HENRY LOWE, of Barnsbury, in the County of
Middlesex, Manufacturers. "IMPROVEMENTS IN THE CONSTRUCTION OF 'DIGI-
TORIUMS, SUCH IMPROVEMENTS BEING APPLICABLE TO PIANOS, ORGANS, AND
SIMILAR INSTRUMENTS."
"
The objects of the present Invention are threefold, viz., to render adjustable by
sure and simple means the weight and depth of touch of the keys in " 'digitoriums'
or dumb key boards, such as are used for strengthening the fingers and wrists of
musicians and others, and also to mount the keys in such a manner as to ensure
their smooth and noiseless action, at the same time allowing of their easy removal
from the case or instrument when desired.
For the purpose of adjusting the weight of touch of the keys a notch is formed
on the upper part of the back of each of the keys in the instrument, and a series
of springs is mounted on the underside of a sliding rail which overlies the back
ends of the keys, and which is adjustable horizontally by means of a screw or by
equivalent means.
These springs bear respectively each on the surface of one of the notches in the
keys, and can be made to exert a varying pressure thereon by causing them to act
at a greater or less distance from the fulcrum pin on which the keys rock as the
adjusting rail is advanced or withdrawn. This object may also be effected by the
use of a roller, to which are attached springs which bear on the ends of the keys,
but in this case the varying pressure will be obtained by causing the roller to
rotate to any required degree, whereby the springs will be shortened or lengthened,
and consequently stiffened or relaxed as the case may be, and they will also be

page_text: made to act on the keys at a greater or less distance from the pins on which the
keys are centred or pivotted.
In order to see at a glance what pressure is applied to the backs of the keys a
disc or marker in connection with the adjustable rail or roller is provided.
In order to render adjustable the depth of touch of the keys a rail of wood or
other suitable material hinged longitudinally to the bottom of the case is placed
beneath them. The back and front edges of this rail overlie the longitudinal hinge,
upon which the rail is thus enabled to be rocked. The back edge of this rail is
connected with a screw, by turning which the back edge will be raised or lowered,
thus effecting a converse movement of the front edge; or the rail may be caused to
rock on its hinge by a lever or equivalent means. The depth of touch at which the
keys have been adjusted, as above described, is ascertained by a scale or index
placed on the cheek of the case at the side of the keyboard.
It will thus be seen that the depth of descent of the forward parts of the keys
will depend upon the height at which the front edge of the underlying rail has
been adjusted.
In order to ensure the perfectly smooth and noiseless action of the keys, and at
the same time to provide an additional security against sideway oscillation and
rattling (beyond what is obtained by the use of the ordinary slot and pin), the keys
are pivotted or centred in the following manner, which, in addition to the advantages
enumerated above, allows of their being easily removed or replaced:-A series of
pins or supports of T shape are fitted tightly into a block or strip of hard wood.
The heads of these pins or supports are rounded or cylindrical in form, and fit
into transverse grooves on the underside of the keys.
A tempered steel spring slotted at one end is attached at its other end to the
underside of the key by screws, and the slotted end of the spring is then passed
beneath the cylindrical head of the pin or support, which will slip into the
transverse groove on the underside of the key, and be retained therein by the
upward pressure of the spring.
For convenience, the underside of each of the keys may be recessed for the recep-
tion of one of such locking springs.
The amount of play of the front parts of the keys will depend upon the height at
which they are centred or pivotted, and upon the extent to which the rear ends of
the said keys are allowed to descend; but in order to arrest the keys in their
normal position, when the pressure on them is removed in a quiet and certain
manner, it is found to be convenient to so arrange the position of the top edge of
the case overlying the front parts of the keys, and the portion of the case on which
the backs of the keys rest when they are in their normal position, that these parts
shall co-operate at the same moment to stop the ascent of the keys.
This arrangement allows of any degree of lift being given to the front ends of
the keys, even to more than one inch if desired.
"
The above arrangements for adjusting the weight and depth of touch of the keys
in a digitorium may be applied to pianos, organs, harmoniums, and similar
instruments, thus providing for the more efficient rendering of various styles of
music. The above mentioned method of centreing or pivotting the keys of
digitoriums" is especially well suited for pianos and such like instruments, by
reason of its smooth, firm, and noiseless action.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, and of
an Order of the Lord Chancellor, filed by the said William Lowe and Thomas
Henry Lowe in the Great Seal Patent Office on the 18th March 1881.
WILLIAM LOWE and THOMAS HENRY LOWE, of Barnsbury, in the County of
Middlesex, Manufacturers. "IMPROVEMENTS IN THE CONSTRUCTION OF 'DIGI-
TORIUMS, SUCH IMPROVEMENTS BEING APPLICABLE TO PIANOS, ORGANS, AND
SIMILAR INSTRUMENTS."
The first part of our Invention relates to improved means for rendering adjustable
in a speedy and efficient manner the weight of touch of the keys in "digitoriums "
or dumb key-boards, such as are used for strengthening the fingers and wrists of
musicians and others.
To this end we employ an axle of wood or metal, to which are attached springs,
preferably of steel, the free ends of the said springs bearing upon the rear ends of
the keys, the amount of pressure exerted by the springs upon the keys being varied
by causing the said axle to rotate to any required degree. The springs will thus
be partially wound upon or unwound from the axle, which is preferably of
cylindrical form, and will be shortened or lengthened, and consequently stiffened or
relaxed, as the case may be. An advantage incidental to this arrangement is the
small space required for this mechanism.
It has been found by experiment that the pressure on the keys may be more
readily varied and applied in an accelerated degree by mounting the cylinder or
axle to which the springs are attached excentrically, or by forming the axle of the
form of a snail cam in cross section. The rotation of the cylinder or axle may be
effected by any suitable means.
Figure 1 is a plan view of so much of a five-keyed digitorium as will serve to
explain this improvement, and Fig. 2 is a longitudinal sectional elevation of the
sane.
A, A, are the keys centred or pivotted at a in a special manner to be hereafter
more fully described.
B is a cylinder or axle, preferably of metal, to which are attached springs b, b, the
free ends of which rest upon the inclined faces cut in the rear ends of the keys A, A.
The roller B is mounted eccentrically in cheeks or bearing plates 61, secured to the
sides of the case. The springs b, b, which are preferably of steel, are each slotted as
shewn at b2 in the detached view Fig. 3, and they are attached to the cylinder or
axle B by means of screws 63. The slots 62 allow of any slight difference in the
initial pressure of the springs upon the keys being compensated for in the act of
securing the springs upon the cylinder, and thus we ensure that all the springs in
the instrument shall exert an equal pressure on their corresponding keys.
We would however remark that should it be required to impart greater
proportional resistance to any one key in an octave, this arrangement for attaching
the springs to the cylinder will admit of this being readily effected.
Thus, if desired, the key which is operated by the weakest finger in the hand may
have a greater proportional pressure put upon it, and by constant practice the
weak member.will in time become as strong as the other fingers.
Keyed or otherwise attached to the pivot pins, on which the cylinder or axle is
mounted excentrically in the bearing plates b', are two lever arms b*, which rest
upon a transverse horizontal bar C, preferably of wood faced with metal; this bar
is raised and lowered in a vertical plane by means of a screw c, which rests in a
footstep c¹ and works in a collar c² fixed to the case of the instrument. The screw c
passes through a threaded collar in the horizontal bar C, thereby effecting

page_text: the raising or lowering of the bar as the screw c is turned in one direction or the
other.
It will thus be seen that when the bar C is in its lowest position, the springs b
will exert a minimum amount of pressure upon the rear ends of the keys A, but
that so soon as the bar C is raised by turning the screw c the free ends of the lever
arms b will be lifted, and the cylinder or axle B will be partially rotated. The
result of this will be to wind the springs b upon the cylinder or axle B and to
shorten their effective length. They will consequently be stiffened and impart an
increased pressure to the rear ends of the keys A.
In order to ascertain what amount of pressure is applied to the keys at any one
time a metal finger or pointer c³, Fig. 4, is attached to one extremity of the
horizontal bar C and projects through a slot in the side of the case, on which is a
carefully graduated scale indicating the weight of touch in ounces corresponding to
the several positions which the cylinder or axle is caused to assume the variation
in the weight of touch, being due to the accelerated stiffening of the springs as they
are gradually wound upon the cylinder or axle and their effective length is
reduced.
In Fig. 5 we have shewn a modification of our improved means for regulating
the weight of touch, which consists in simply reversing the position of the springs
with respect to the keys on which they bear. From this Figure it will be seen
that the free end of each spring instead of resting on its corresponding key at a
point between the fulcrum pin a and the cylinder or axle B now rests upon the
extreme rear end of the key. This arrangement effects considerable economy of
space and allows the instrument being made of a very compact shape.
The rotation of the cylinder or axle B in this arrangement we preferably effect
by means of a worm-wheel d, in gear with a worin d' upon a short vertical
spindle D, having a milled head or formed as a thumb-screw.
The principle of action is however precisely the same in this as in the first
described arrangement, the increasing weight of touch being due to the increased
stiffness of the springs b, which results from their being shortened up. The rotation
of the cylinder or axle B may be effected by other simple mechanical means should
the necessities of the caser equire it, and as above remarked a greatly accelerated
pressure may be applied to the keys by constructing the axle B in the shape of a
snail-cam in cross section.
The second head of our Invention relates to improved means for rendering
adjustable the depth of touch of the keys in "digitoriums," pianos, and similar
key-board instruments. For this purpose we provide a flat rail of wood or other
suitable material having its under surface bevelled off in front and rear, as shewn
in cross section in Fig. 2.
This rail E we hinge to the bottom of the case, as shewn by the dotted lines of
Fig. 1, in such a way that the said rail is free to rock on a longitudinal axis passing
through the point e, the bevelled under surfaces e¹ and e² allowing of this
movement.
4
Attached to the rearward edge of this rocking rail, and preferably midway of its
length, is a metal bracket e³, which is connected by a simple hinge joint with one
end of a screw F, which works in a threaded sleeve f keyed to or formed in one
with a short spindle attached to a milled head f¹. It will now be seen that the
depth of touch of the keys, or, in other words, the extent to which they are allowed
to descend on being struck may be at once adjusted by turning the threaded
sleeve f, which will raise or lower the back edge of the rail E, thus effecting a 5
converse movement of the front edge e¹.
It will be obvious that the rail E may be caused to rock on its hinge or hinges
by a lever, or by equivalent means.
The depth of touch to which the keys have been restricted by means of this
rocking rail E is ascertained by a scale or index placed on the check of the case.at 5
the side of the keyboard, as shewn by dotted lines in Fig. 2.

page_text: The third bead of our Invention relates to an improved means for pivoting the
keys of digitoriums, pianos, organs, and similar keyboard instruments.
In order to ensure the perfectly smooth and noiseless action of the keys, and at
the same time to provide an additional security against sideway oscillation and
rattling (beyond what is obtained by the use of the ordinary key pin), we centre
the keys in the following manner, which, in addition to the advantages enumerated
above, allows of the keys being easily removed or replaced:-
This arrangement is illustrated in Fig. 2, 5, and 6. A series of T shaped
pins or supports G are fitted tightly into a horizontal block or strip of hard
wood H, underlying the keys and running transversely thereof.
The heads of these pins or supports G are rounded or cylindrical in form, and fit
into transverse grooves a formed on the underside of the keys A.
A tempered steel spring g slotted at one end to allow of its passing on each
side of the stem of the T shaped support G is attached at its other end to the
underside of the key by screws g', and the slotted end of the spring is then passed
beneath the cylindrical head of the pin or support G, which slips into the transverse
groove a formed on the underside of the key A, and is retained therein by the
upward pressure of the spring g. An end view of this arrangement is shewn
in Fig. 6.
To economise space the underside of the keys A may be recessed for the
reception of the said retaining springs, as shewn in Fig. 2 and 5; but this recessing
of the keys is not necessary for the efficient working of this part of the Invention.
The amount of play on the front parts of the keys will depend upon the height
at which they are centred or pivotted, and upon the extent to which the rear ends
of the said keys are allowed to descend; but in order to arrest the keys in their
normal position when the pressure on them is removed in a quiet and certain
manner it is found to be convenient to so arrange the position of the top edge of
the case overlying the front parts of the keys, and also that portion of the case on
which the backs of the keys rest when they are in their normal position, that these
parts shall co-operate at the same moment to arrest the upward tendency of the
keys, by which arrangement any jarring action is avoided.
This arrangement allows of any necessary degree of "lift" being given to the
front ends of the keys, but it is found that an inch is amply sufficient for all
practical purposes.
in a 60
The above arrangements for adjusting the weight and depth of touch of the keys
digitorium may be applied to pianos, organs, harmoniums, and similar
keyboard instruments, thus providing for the more efficient rendering of various
styles of music.
"
The above mentioned method of centreing or pivoting the keys of " digitoriums
is especially well suited for pianos, organs, and such like keyboard instruments by
reason of its smooth, firm, and noiseless action.
Having now described the nature of our Invention of "Improvements in the.
Construction of 'Digitoriums,' such Improvements being Applicable to Pianos,
Organs, and similar Instruments," and explained the manner of carrying the same
into effect, we wish it to be understood that under the above in part recited Letters
Patent we claim,→
First. Imparting to the keys in "digitoriums," pianos, and similar keyboard
instruments, a varying pressure or weight of touch by means of a series of springs
mounted upon an axle, the said springs being stiffened or relaxed by the partial
rotation of the axle, substantially in the manner and for the purpose herein shewn
and described.
Second. Adjusting the depth of touch of the keys in "digitoriums," pianos,
and similar keyboard instruments, that is to say, limiting the depth of descent
of the said keys by means of a rocking bar or rail, arranged and operated
substantially as herein shewn and described.
Third. Mounting the keys in digitoriums, pianos, organs, and similar keyboard

page_text: instruments upon bearing pieces or supports, in the manner and for the purpose
herein shewn and described.
In witness whereof, I, the said Thomas Henry Lowe, have hereunto set my
hand and seal, the Sixteenth day of March, in the year of our Lord One
thousand eight hundred and eighty one.
T. H. LOWE. (L.S.)