June 30, 1831
Ebenezer R. Currier
Letters Patent
The schedule referred to in this Letters Patent and making part of the same containing a description in the words of the said Ebenezer R. Currier himself of his improvement in the horizontal square pianoforte.
Know ye that I the said Ebenezer R. Currier, have invented a new and useful improvement in the horizontal square Piano Forte, whereby each of the hammers is made to strike one of more of the strings belonging to its proper note at the pleasure of the performer, as is done in the horizontal grand piano forte. And by means of the said invention the following advantages of construction in horizontal piano fortes are obtained namely
First, that the key board may be placed exactly mid way of the instrument, which gives the advantage of a compass of seven octaves and admits of greater beauty & symmetry in the exterior of the instrument.
Secondly, the key frame may be supported by a brace, which is secured to the lower frame of the case by bolts, of screws passing through supporters of the braces,
Thirdly, the braces of the instrument may [occur] in the direction of & very near to the strings, by which means this instrument may be made stronger and lighter & will keep on tune much better than upon the common construction.
Fourthly, it admits of having a larger sounding board than upon the common construction, which several advantages of construction I also claim as my invention.
And I do hereby declare that the nature of my said invention & the manner in which it is to be made to operate and be carried into effect are fully set forth in the following specification that is to say:
The action, in my piano fortes, consists of the following parts: which are arranged and combined is [...]
A rail which I call the hammer rail extends from the upper to the lower part, of the [...] of the piano forte, on the upper side of this rail, & at an oblique angle with its line of direction is placed a range of levers, which I call the hammer levers. & which with their springs are inserted in their flanges attached to the back edge of the hammer rail, and their hammer levers correspond to and are connected as hereinafter mentioned, with the hammers which are placed on the under side of said hammer rail. The hammer levers project over the jack, (which is of the usual construction) and motion is communicated to the hammer by a connecting rod with passes down from the hammer lever, & is inserted into the [end] of the hammer sockets which are suspended under said rails by flanges with metal pivots.
The hammers may be either parallel with or at right angle or any other angle with the direction of the strings. Each hammer in its ordinary situation will strike all the strings belonging to its note ; but by means of a pedal, which acts upon the hammer rail, the whole range of hammers may be thrown into such a position, that each of them shall strike one or more of its proper strings at pleasure.
The hammer rail is adjusted by means of pivots which are placed in a line with the [ends] of the hammer levers in such a manner that the hammers may be moved, so as to strike the strings in the maner above described without altering the point of contact between the lever & the jack. The whole construction of the action is such as to present the usual [...] of the hammers.
The dampers are placed under the key frame & near the back end of each hammer socket, they damp upon the same side of the string that is struck by the hammers ; they also damp at a greater distance from the bridge than is usual in the common construction of piano fortes, by which means the damping is more effectual ; the dampers are moved by a catch upon the top of their levers, which catch is acted upon by a hook inserted into the under side of the keys & the whole of the dampers may be thrown off the strungs by means of a pedal.
And I do further annex to these points a drawing of my said invention and infer to the same in manner manner following to wit.
AA, are said [...] of the hammer rail with its pivot plate on its ends by screws. B. Is the hammer levers, C the springs of the hammer lever. D the flange of the hammer lever, E, the connecting rod passing from its pivot e in the hammer lever to its pivot f in the end of the hammer socket F, F, G, the flange of the hammer socket, H, the hammer in its natural position, II the strings, K, one of the two pivots on which the hammer rail turns in order to move the hammers, so as to strike one or more of their strings at pleasure. L, the damper, M, the damper lever, under the key frame P. N, the damper lever catch on which the hook (o) from the key acts, O, the hook from the key, acting on the catch of the damper lever, P, the key frame, Q, the damper lever frame. R, R, the key & jack.
In testimony that the above is a true specification of my said improvement as above described, I have hereto set my hand & seal, this second day of April in the year of our Lord on thousand eight hundred and thirty one,
| Ebenezer Currier |
| Witnesses Joseph Sprague Geo. Hews |