The "Rolmonica" is a small portable (coat-pocket size) musical instrument from the 1920s which uses a conventional "harmonica" or "mouth organ" to play recorded music from a roll of paper. Its operating principle is similar to that of the American Organette described previously, in that the holes in the paper roll are used as valves to control the flow of air through the harmonica reeds. The main difference, apart from size and portability, is that the air is supplied directly by the player's breath rather than by mechanical bellows.
There are at least four versions of the American-made Rolmonica:
This page gives a brief history of the Rolmonica and shows the development of the various models.
Although often described as a "novelty" instrument with a scale of only 12 notes, the "jazzy" Rolmonica arrangements were often surprisingly effective with the music of the time. Here are a couple of MIDI files of typical examples, each scanned and re-mastered from original music rolls from the late 1920s:
There are more downloadable MIDI files on the Rolmonica Music Files page.The Rolmonica was developed during the Roaring Twenties, a time of great social and technological change across most of the Western world. The Great War was over, and folk everywhere were embracing the modern age with enthusiasm. For the first time there were practical and affordable motor cars, moving and then talking pictures, electrical appliances for the home, and even the prospect of travel by air. Socialising was freed from its Victorian formality and dancing was all the rage. The music of the jazz and dance bands was distributed far and wide through the gramophone, the player piano, and the magic of radio broadcasting.
In the USA one Joseph Le Roy Banks of Baltimore saw an opportunity to spread the music even further by attaching a miniature roll-playing mechanism to a low-cost harmonica or mouth organ. In July 1922 he filed a patent application for what eventually became the very popular "Rolmonica". Banks was quite an active inventor who already held several patents in unrelated fields. He was not the first to develop a roll-playing harmonica, but he had the good fortune to be in the right place at the right time, and was the only one to achieve significant sales.
His original concept was to mount a standard harmonica in a metal frame with a mouthpiece at the front. Roll spools would be mounted on simple brackets above and below the harmonica, and the paper would be cranked through by hand. Air blown through the mouthpiece would pass through the holes in the paper to play the corresponding notes on the harmonica. Unfortunately the gap between the mouthpiece and the harmonica (through which the paper had to pass) allowed most of the air to escape, making this simple concept quite impractical.
Banks eventually solved the air-leakage problem by enclosing the whole of the roll mechanism in a metal "clam-shell" case. The cross-section opposite shows similar front and rear shells, hinged together at the bottom and held closed by a simple clip at the top. Air entering through the mouthpiece (left) fills the two spool chambers, but can only leave through the harmonica.
The Rolmonica Manufacturing Company was formed in Baltimore at the end of 1923, the Rolmonica Sales Company in 1925, and the 12-note metal-cased instruments were put into production. Quantities are unknown, but these early instruments are quite rare today.
Early in 1927 the two businesses were restructured as the Rolmonica Music Company, with Banks as President. The rather plain body of the pressed-metal Rolmonica was soon replaced by a much more elegant version in moulded Bakelite. The new model went on sale in May 1928 at a retail price of US$2.50, or about US$45 in 2025 money. The price included four music rolls, with new rolls released every month at 10 cents each. Bakelite was the first modern synthetic "plastic", and was still a new and rather exotic material in 1928.
The new Bakelite Rolmonica was an instant success, and soon became a serious national and international craze. Demand far exceeded supply, even after a major expansion of the factory. In the lead-up to Christmas 1928 one New York store reported that 4000 Rolmonica customers had to be turned away through lack of stock. Sales continued strongly during 1929, with advertising often featuring the music and celebrities from the latest Broadway shows. The success was such that the Company began to develop a new "Chromatic Rolmonica" with a larger and more capable 16-note scale.
The "beginning of the end" of the Roaring Twenties came suddenly with the stockmarket crash of October 1929, followed by the slow descent into the Great Depression. The Rolmonica Music Company continued on through the rest of 1929, still mass-producing the Bakelite Rolmonica and releasing new rolls of the hits of the day. In February 1930 they announced that production was now so efficient that the retail price would be reduced to US$1.50 (with only one roll), or $8.50 per dozen to dealers.
The new Chromatic Rolmonica was announced in April 1930 at a price of US$2.50 including one roll, with extra rolls at 15 cents. The announcement mentioned that "the first model ran into the production of millions" in just two years, and that it would continue to be produced. Almost 400 roll titles had been produced for the 12-note instrument, but relatively few more were issued as the focus turned to the larger model.
By June of 1930 the Depression was starting to bite. Advertising and promotions for the Chromatic Rolmonica continued throughout 1930, with 8 or 10 new roll titles being issued every month. The price of 12-note rolls increased by 50% to 15 cents, but the financial situation soon became desparate. The regular listings of new rolls in the trade press ceased in December 1930, and in early 1931 the Rolmonica Music Company was declared bankrupt. A receiver's auction for disposal of all "materials, machinery and equipment" was advertised for the 3rd of June 1931.
The receiver's auction was not the end of the story. Rolls and roll
boxes from this period can be found under the name of the (previously
unknown) Baltimore Rolmonica Company
rather than the Rolmonica Music Company. A new 12-note "Rolmonica Player
Harmonica" with a moulded front and pressed-metal back was produced in
packaging with the Baltimore Rolmonica
Company label, and appeared regularly in mail-order catalogs until at
least 1938. New 12- and 16-note music rolls of the latest hits continued
to appear during the 1930s, although much more slowly than before. It
seems likely that the Rolmonica Music Company may have been bought out
or restructured after bankruptcy, and operations may have continued for
a period under a new name and management. Further investigation must
wait for another time.
The sound produced by the Rolmonica comes entirely from a more-or-less standard commercial harmonica. The 16-note "Chromatic" harmonica (top) is marked as made by Hohner, the largest harmonica-maker in Germany. The 12-note instruments are marked "Made in Germany" and are thought to be from the same source. The cover plates are actually bright nickel plated, but are photographed here with a black reflection to make the text more legible.
Although built in the conventional manner, the Rolmonica harmonica has one important difference from the hand-played instruments. In a normal "10-hole" harmonica each hole can produce two different notes, depending on whether the player blows or draws air through the hole. In the Rolmonica the notes are selected by the paper roll rather than by the player. Each hole position must always produce the same note, regardless of whether the player blows or draws air at any moment. So while a hand-played 10-hole harmonica can play 20 notes, a 12-hole Rolmonica can play only 12.
The musical scale of the 12-note harmonica extends from E5
(MIDI note 64) to C7 (MIDI note 84):
E F G B C D E F G A B C.
For reasons unknown, the positions of the top two notes are reversed
on the 12-note harmonica and on the music rolls. The physical placement of
the notes is:
E F G B C D E F G A C B.
The scale of the 16-note Chromatic harmonica provides more notes, but with a reduced range or compass. It extends from the same E5 (MIDI note 64) to A6 (MIDI note 81) in ascending order: E F# G# A A# B C C# D D# E F F# G G# A.
The harmonicas are mounted in the instruments with the low notes on the same side as the winding handles.
Internally, the harmonicas are built on a wooden core or comb, with brass reed plates attached on each side. The reed tongues are riveted alternately above and below close-fitting slots in the reed plates, and are protected by decorative cover plates on each side. The core of the 12-note harmonica (opposite) measures 98x25x6.5mm. The reed cells are 4.6mm wide with a 1.8mm separator between, for a note spacing of 6.4mm or 1/4". The 16-note core is only slightly larger at 100x27x6.5mm, but the reed cells are smaller at 4mm wide, with only 1.3mm separators. The reed plates in both models are 0.9mm thick. The cover plates bring the total thickness to about 18mm or 3/4".
The ability to play two notes per hole depends on the fact that "free reeds" will only speak when the air flow pushes them into the slot in the reed plate. In the photo opposite the rightmost reed is mounted on the upper surface of the upper reed plate, so air must be drawn from the hole in order for the reed to speak. A second reed mounted on the upper surface of the lower reed plate would not speak, but would allow air to pass freely. Blowing into the hole would reverse the situation - the lower reed would speak, while the upper would allow the air to pass. In a hand-played harmonica the upper and lower reeds can be tuned to different notes, but in the Rolmonica they must be tuned exactly the same.
Because the air has to be provided by the player's breath, the reed plates are usually fitted with "flap valves" or "wind-savers" to block the loss of air through the non-speaking reeds. These valves were originally made from thin flaps of leather or rubberised cloth, which have usually hardened, twisted, or fallen off with age. The replacements shown in the photo are made from thin (0.01" or 0.25mm) leather.
The music rolls for the Rolmonica are made from very thin brown paper typically only 0.0015" (0.04mm) thick, or about one-third as thick as normal office paper. The paper has a thin wax coating to prevent absorbtion of moisture from the player's breath. The photo shows typical perforation patterns for 12-note (left) and 16-note rolls. The individual punch strikes are clearly visible in both rolls.
The 12-note rolls are nominally 3-1/4" wide. The round punches are 3/16" diameter with the tracks spaced 1/4" apart (to match the harmonica), leaving a margin of 3/32" on each side. The paper advance between punch strikes is a constant 3/32". Most 12-note tunes in 4/4 time were arranged in 32 bars, using 12 punch steps per quarter note, giving a roll length of about 12 feet (1550 steps) and a playing time of about one minute.
The 16-note rolls are 3-3/4" wide, with the punches reduced to 5/32" diameter. The note tracks are 5.3mm (about 13/64") apart, as required to match the harmonica. The paper advances a constant 1.7mm (just over 1/16") between punch strikes. The 16-note rolls are slightly longer (15ft instead of 12) and travel more slowly (8ft per minute instead of 12), giving an increased playing time of almost two minutes.
The paper "tune sheet" was wound onto a simple wooden spool with metal ends. The illustration shows an empty spool, a 12-note roll, and a 16-note Chromatic roll, all viewed from the driving end. The wooden cores are 3/8" in diameter, although there were some early spools with 5/32" cores. The metal end flanges are 0.020" thick, which makes the overall width about 1/16" greater than the nominal paper width. The end flanges were originally made 15/16" in diameter, but this was increased to 1" in 1930 to add an extra 3ft of paper for the new Chromatic instrument.
Note that the 12- and 16-note rolls are wound onto the spools in opposite directions, to suit the different paper paths through the two instruments.
The Rolmonica name, the roll number, and the tune title were rubber-stamped onto the "leader" at the start of the roll. The ink did not take well to the wax-coated paper, and has generally been rubbed away from any roll that has been handled more than a few times. The illustration shows two well-preserved examples of early and late leader stamps. The 12-note rolls usually have the roll number punched at the end for permanent identification.
This close-up view shows the two ends of the spool with their central locating dimples. The right-hand end has a central rectangular slot, 0.100" x 0.040" approx, which engages with the flattened ends of the Play and Re-roll cranks to drive the roll in either direction.
The early metal-cased Rolmonica had no Play or Re-roll cranks on the instrument itself. Every roll spool, including the empty take-up spool, carried its own axle and a simple crank formed from stiff wire. This could lead to great confusion if a played-through roll was removed from the instrument without being re-wound.
Later 12-note rolls were packaged in simple one-piece cardboard boxes with a constant design but varying colour schemes. The early black-on-orange box has no price marking; the black-on-white is marked 10 cents, and the brown-on-white has a 15-cent sticker over the printed 10 cents, indicating that it was made after mid-1930. Some roll boxes from this period carry the name of the Baltimore Rolmonica Company rather than the Rolmonica Music Company. Note that the RMC box has a 15-cent sticker, while the later BRC box has a printed 15 cents.
The photo opposite (from Ebay) shows the front view of an early production version of the metal-cased Rolmonica. The casing consists of two similar pressings, hinged in "clam shell" fashion at the bottom and held closed by a simple clip at the top. The mouthpiece is at the centre of the front shell, and the harmonica is mounted horizontally across the rear. When closed, the casing forms two cylindrical chambers to contain the music roll (top) and the take-up spool below. The spool axles are located in suitable channels in the side flanges. The two halves of the casing are sealed by a felt gasket around the outer flanges. The enclosed construction eliminates the leakage problems with Banks' original concept, and ensures that all the air provided through the mouthpiece is directed to producing sound through the harmonica.
The paper path is from the underside of the supply spool, over a Pianola-style "tracker bar" in front of the harmonica, and on to the underside of the take-up spool. A brake is applied to the supply spool to ensure that the paper is under sufficient tension to prevent it being drawn away from the harmonica under suction. The brake is a metal strip inside the upper chamber, which bears against the end flange of the spool. The brake is attached via the single rivet at the far left of the mouthpiece.
"Bakelite", invented by Leo Baekeland, was the first of the modern "plastics". It consisted of a synthetic chemical resin which could be mixed with suitable fillers and moulded into any desired shape. The mouldings were then "cured" under heat and pressure to form hard, strong and durable objects. Although patented in 1909 it was still a fairly new and exotic material in the mid-1920s, and was well suited to the spirit of the times. The newly-formed Bakelite Corporation was actively engaged with companies in many different industries to develop new applications for their "material of a thousand uses". It seems likely that the Rolmonica company worked closely with Bakelite staff in developing and refining the new model and bringing it into volume production. The words "Genuine Bakelite" are moulded on the inside of the case. The Bakelite Corporation was obviously well pleased with the result, as it featured the Rolmonica story in some of its own advertising to the trade.
The fiery orange and red colouring was a surface coating applied to the outside of the mouldings, which became a permanent part of the Bakelite during the process of curing. The random colouring added much to the attraction of the Rolmonica, but it can also be taken as a warning: some early Bakelite objects contained asbestos as one of many common fillers. The fillers are held very tightly by the cured resin and are unlikely to cause any problems today.
The front of the instrument carries the patent dates 11-3-25 and 6-5-28, corresponding to Banks' original patent US1560497 and its later re-issue RE16986.
The Rolmonica was supplied in a simple
cardboard box 3-1/4" square
and 5-1/4" tall. The instrument was packaged with its left-hand end
at the bottom of the box and the body held diagonally between the
corners of the tall sides.
The Bakelite Rolmonica is essentially a direct conversion of the previous metal-cased design into the new material, but with a few significant changes. The dimensions are much the same at 4" wide by 3-1/2" high. The body is only 1-1/4" thick over the spool chambers, with the mouthpiece extending 1" at the front and the harmonica 1/4" at the rear. The clamshell case was divided 1/4" closer to the front (rather than along the centre line of the spools), thus allowing the spool and crank bearings to be securely attached to the walls of the rear casing. The felt seal between the two halves was replaced with a gasket of white rubber tubing.
The take-up spool was permanently installed, while the supply spool was held between two domed pins, one fixed on the left-hand side and the other spring-loaded inwards. A thumb tab next to the Re-roll crank was used to withdraw the pin when changing the roll. Each of the wire cranks had a small wooden handle, and a flattened driving end which engaged with a matching slot in the right-hand ends of the roll spools. The harmonica was held between shallow arms at each side of the rear casing. It was sealed against the inside of the Pianola-style "tracker bar" by a cork gasket, and held in place by two decorative panel pins.
The paper path was the same as in the previous model - from the underside of the supply spool, over the tracker bar, and on to the underside of the take-up spool. The roll spools both turn clockwise while playing. The function and direction of each crank was clearly marked on the front face of the instrument - clockwise on the lower crank to Play, anticlockwise on the upper crank to Re-roll.
The Bakelite Rolmonica deleted the brake on the supply-spool and relied on friction from elsewhere to keep the paper tight over the tracker bar. Some of the friction came from the increased wrap of the paper over the bar (which was now 1/4" forward of the spool axles), and some from the strong axial spring in the supply-spool bearing. Even so, it was not difficult to pull the paper away from the bar on strong Draw notes, thus causing unintended notes to sound.
In November 1928 Banks filed a rather ill-conceived US patent (1798055) which attempted to address the problem. This idea was not applied to the Bakelite Rolmonica, but was developed further and used (still unsuccessfully) in the later Chromatic instrument.
The Chromatic Rolmonica was developed during 1929 and was announced to the public in April 1930, just at the start of the Great Depression. Its main aim was to provide a full chromatic scale (ie, including all five of the "black keys"), so that "any piece of music can be used and played on it". It also doubled the playing time (to almost two minutes) and made further attempts to solve the problem of unintended Draw notes.
The instrument is made from a dark brown moulded Bakelite (or similar) material, but is no longer labelled as "Genuine Bakelite". The body is slightly larger than the 12-note model at 4-5/8" wide and 3-5/8" high, but is only 1-3/8" thick. The mouthpiece has been shortened and moved upwards, so that the overall thickness is only 2". The body has a smoothly-curved and patterned front and a flat back, with the harmonica contained entirely within the body.
The two US patent numbers on the front face are RE16986, for the re-issue of Banks' original 1922 application, and 1720991 for improvements to the metal-cased instrument. The latter patent was issued in July 1929, indicating that the design for the Chromatic body was not finalised until after that date.
The construction of the Chromatic Rolmonica is similar to that of the 12-note instrument, using the same hinges, clip, and rubber-tubing gasket. The thumb tab to release the supply spool has been replaced with a spring-loaded pin at the left-hand side.
To increase the playing time, the holes in the paper roll were made smaller and closer together. This required that the paper should travel more slowly to play at the correct tempo. To keep a more comfortable cranking speed, a small 3:2 (actually 22:14) reduction gearset was inserted between the Play crank and the take-up spool. The 22-tooth gear is visible on the end of the spool. The Play crank is now at the extreme end of the body rather than in line with the spool axis.
The revised paper path in the Chromatic Rolmonica was developed from the idea in Banks' 1928 patent US1798055. The harmonica and its moulded "tracker bar" have been moved forward by 3/8" (10mm) and now protrude into the front section of the case. The paper travels from the top of the the supply spool, over the tracker bar, and on to the top of the take-up spool. The two cross-bars on the inside of the front casing force the paper well down on each side of the tracker bar in an attempt to keep it from being drawn away under suction.
The relocation of the mouthpiece into the upper section of the case means that the air has to force its way under the upper cross-bar in order to reach the harmonica. This, combined with the smaller reeds, reduces the air flow and the sound output.
The change in the paper path reverses the rotation of the roll spools, so that both turn anti-clockwise while playing. The gearing also reverses the direction of the lower crank, so that it still turns clockwise to Play. The upper crank now turns clockwise to Re-roll. Both directions are marked on the front face of the instrument.
Moving the tracker bar 3/8" forward brought the rear of the harmonica level with the back of the spool chambers. This provided a smooth and flat back surface, and allowed the instrument to be packaged flat in a more elaborate two-part box.
An early illustration advertising the "new" Chromatic Rolmonica shows several differences from the production model. The music roll is shown installed in the same manner as in the previous model, which would require crank directions opposite to those marked on the front face. The Play crank is shown in line with the axis of the take-up spool, indicating that the reduction gearing was a fairly late addition. The illustration also suggests that the Chromatic would retain the red and black colouring, whereas the production instruments are almost completely black.
This final version of the 12-note Rolmonica appeared in the 1930s, some time after the Rolmonica Music Company was declared bankrupt in 1931. The packaging carries the name of the (previously unknown) Baltimore Rolmonica Company. At first glance the instrument appears very similar to the previous models, except that all of the mechanism is now attached to the Bakelite front half of the case. The pressed-metal back is just a protective cover, hinged at the top and completely open to the air.
The body dimensions are much the same at 4-1/4" wide, 3-1/4" high, and 1-3/8" thick, with the central mouthpiece extending 3/4". The front has a similar design to the Chromatic, but is flat rather than curved. It carries the label "Player Harmonica", and the same two patent dates.
Turning the instrument over (top to bottom) reveals that the "front" of this instrument is actually the back of the previous models. Rather than sealing the whole instrument, this version only seals the harmonica inside a smooth metal shroud. The harmonica is pinned inside the shroud with the usual cork gasket under the tracker bar, and the whole assembly is pinned to the case with another cork gasket underneath.
The Bakelite front of the previous casing has been discarded, and replaced with a light sheet-metal cover. The mouthpiece has been moved to the what used to be the back, and now supplies air directly to the back of the harmonica rather than to the "tracker bar" holes at the front. This (in theory) makes no difference, as the harmonica should respond equally to air flow in either direction.
Because the harmonica was fully enclosed by the metal shroud, its protective cover plates were not required. Only the wooden core and the two reed plates were installed inside the shroud.
The paper path returned to the original "under-to-under", but with a greater wrap around the protruding tracker bar. The problem of lifting the paper away from the bar on Draw notes was transferred to Blow notes, but was lessened by the greater wrap and a new friction washer on the supply spool crank.
When the instrument is turned over to the (right-handed) playing position, the Play crank (and the hinge) are at the top rather than the bottom. The Play crank at the top still turns clockwise, while the Re-roll crank at the bottom turns anti-clockwise. Both directions are marked on the front face.
The instrument was packaged in a tall cardboard box similar to that of the first Bakelite Rolmonica.
Rolmonica Music Company box.The cross-sectional drawings following summarise the internal development of the Rolmonica, from the original concept to the final production version. The drawings have been adapted by the author from those in Banks' US patents.
Banks' original concept was to fit a standard harmonica into a metal frame, with roll spools above and below and a mouthpiece to distribute air across the full width. The difficulty of sealing the gap between the mouthpiece and the harmonica (through which the paper had to pass) made this simple concept quite impractical.
Banks recognised the problem and proposed alternative constructions in the same patent application. This version reduces air loss by providing a longer enclosed paper path, but increases the difficulty of loading the paper roll. The drawing appears to show the whole mouthpiece hinged at the bottom so that it can be opened to provide access.
Rather than just hinging the mouthpiece, Banks eventually decided to enclose the entire mechanism in a metal "clam-shell" case, hinged at the bottom and opening to provide clear access for loading and removing the paper rolls. The sealed case solved the air-leakage problem, and made the instrument much easier to handle.
The production versions of the metal-cased Rolmonica had wire cranks attached to every wooden roll spool, as shown in the original concept drawing. Patent 1720991, filed December 14 1927, shows a metal-cased instrument with the cranks removed from the spools and replaced with spring-loaded cranks and bearings permanently attached to the centre line of the casing. This improved design did not appear in the production instruments, but was developed further for use in the forthcoming new model.
The Bakelite Rolmonica was essentially a direct conversion of the metal-cased version into the new material. The main difference was that the clamshell case was divided 1/4" closer to the front (rather than along the centre line of the spools), thus allowing the new spool and crank bearings to be securely attached to the walls of the rear casing.
The Bakelite Rolmonica could sometimes produce unwanted sounds if strong Draw notes pulled the paper away from the tracker bar. Banks' US patent 1798055 addressed this problem by extending the core of the harmonica through the Bakelite casing and into the airway in the front half of the casing, so that the edges of the airway would hold the paper down.
This required a separate metal "tracker bar" cap to be fitted to the wooden core, which would have made assembly and service impractical. This idea was not used in production.
Banks continued to develop the previous idea for use in the new Chromatic Rolmonica. The harmonica and the moulded tracker bar were moved forward, so that they protruded well into the front half of the case. Two cross-bars were added inside the front, to hold the paper down on each side of the tracker bar. The paper path was changed to travel from top to top of the spools, so as to produce a sharp bend and increased tension at the cross-bars. Even so, it was still possible to produce spurious notes on moderate to strong suction, and the bends were not kind to the thin perforated paper.
The mechanical changes allowed the Bakelite case to be re-designed into a simpler form with a flat back and a gently curved front. The relocation of the mouthpiece provided a better view for (and of) the player, but greatly restricted the air flow to the harmonica.
While looking long and hard at the previous drawing, somebody from the newly-formed Baltimore Rolmonica Company realised that he or she could throw away the entire front half of the Bakelite case, restore the paper path to "under to under", move the mouthpiece around to the other side, and supply air to the harmonica in the opposite direction with no change to the theory or practical operation.
To be able to install and service the harmonica, the Bakelite moulding and tracker bar surrounding it was replaced by a similar but removable pressed-metal shroud, which was sealed to the flat Bakelite casing with a simple cork gasket. The discarded Bakelite "front" was replaced with a simple hinged metal "back" as a protective cover.
Several other portable roll-playing instruments were developed and sold during the 1920s and 30s. The German "Triola" mechanical zither and the "Tanzbaer" automatic accordion were intended as serious musical instruments, and were capable of quite good performances - after considerable practice. The "novelty" or "anyone can play it" category included the Rolmonica, the Play-A-Sax, and the PlaRola. The Play-A-Sax was a 12-inch parody of a saxophone incorporating a harmonica and a rather cumbersome roll mechanism. The PlaRola was similar in size and operation to the Rolmonica, but with a rectangular metal casing painted to resemble a pipe organ (as shown in the design patent opposite). Both instruments played 16-note paper rolls about 4-1/2" wide. The PlaRola sold for US$2.30 in 1938, and the Rolmonica for US$2.50. Their relative success is shown in the current second-hand market: the Bakelite Rolmonica is still readily available, but the Play-A-Sax and the PlaRola are now quite rare.
This section lists a number of US patents related to the Rolmonica, its inventor Joseph Le Roy Banks, and its competitiors. The patents are listed in order of application. Copies of the patents can be downloaded free from uspto.gov or patents.google.com I have not found any patents specific to the Chromatic or metal-backed instruments.
