COR ANGLAIS, or English Horn (Ger. englisches Horn or alt Hoboe; Ital. corno inglese), a wood-wind double-reed instrument of the oboe family, of which it is the tenor. It is not a horn, but bears the same relation to the oboe as the basset horn does to the clarinet. The cor anglais differs slightly in construction from the oboe; the conical bore of the wooden tube is wider and slightly longer, and there is a larger globular bell and a bent metal crook to which the double reed mouthpiece is attached. The fingering and method of producing the sound are so similar in both instruments that the player of the one can in a short time master the other, but as the cor anglais is pitched a fifth lower, the music must be transposed for it into a key a fifth higher than the real sounds produced. The compass of the cor anglais extends over two octaves and a fifth:
The true quality of the cor anglais is penetrating like that of the oboe, but mellower and more melancholy.
The cor anglais is the alto Pommer (q.v.) or haute-contre de hautbois (see Oboe), gradually developed, improved and provided with key-work. It is not known exactly when the change took place, but it was probably during the 17th century, after the Schalmey or Shawm had been transformed into the oboe. In a 17th century MS. (Add. 30,342, f. 145) in the British Museum, written in French, giving pen and ink sketches of many instruments, is an "accord de hautbois" which comprises a pédalle (bass oboe or Pommer), a sacquebute (sackbut) as basse-contre, a taille (tenor) with a note that the haute-contre (the cor anglais) est de mesme sinon plus petite. The tubes of all the members of the hautbois family are straight in this drawing. Before 1688 the French hoboy, made in four parts and having two keys, was known in England.  It is probable that in France, where the hautbois played such an important part in court music, the cor anglais, under the name of haute-contre de hautbois, was also provided with keys. At the end of the 17th century there were two players of the haute-contre de hautbois among the musicians of the Grande Ecurie du Roi. 
Fig. 1. - Modern Cor anglais. (Besson & Co.)
From Richard Hofmann's Katechismus der Musikinstrumente.
Fig. 2. - Cor anglé, 18th century.
The origin of the name of the instrument is also a matter of conjecture. Two theories exist - one that cor anglais is a corruption of cor anglé, a name given on account of the angular bend of the early specimens. In that case the name, but not necessarily the instrument, probably originated in France early in the 18th century, for Gluck scored for two cors anglais in his Italian version of Alceste played in Vienna in 1767. When a French version of this opera was given in Paris two years later, the cor anglais, not being known or available there, was replaced by oboes. It was not until 1808 that the cor anglais was heard at the Paris Opera, when it was played by the oboist Vogt in Catel's Alexandre chez Apelle. This, however, proves only that the name was not familiar in France, where the oboe of the same pitch was called haute-contre de hautbois. The bending of the tube and the development of the cor anglais as solo instrument originated in Germany, unless the oboe da caccia was identical with the cor anglais, in which case Italy would be the country of origin. Thomas Stanesby, junior, made an oboe da caccia in 1740 of straight pattern in four pieces, having a bent metal crook for the insertion of the reed and two saddle keys; but the bell was like the bell of the oboe, not globular like that of the cor anglais, a form to which the veiled quality of its timbre is due. It is interesting in this connexion to recall some experiments in bending the cor anglais, which do not appear to have led to any practical result. A French broadside (c. 1650), "La Musique," preserved in the British Museum, contains drawings of many musical instruments in use in the 17th century; among them are an oboe with keys in a perforated case, and two other wood wind instruments of the same family, which may be taken to represent attempts to dispose of the inconvenient length of the haute-contre (1) by bending the tube at right angles for about one quarter of its length from the mouthpiece, which contains a large double reed, (2) by bending the tube in the elongated "S" shape of the corno torto or bass Zinke, for which the drawing in question might be mistaken but for the bent crook inserted in the end for the reception of the reed, which, however, is missing. The other hypothesis is that when the cor anglais was given a bend in order to facilitate the handling, the name was adopted to mark its resemblance to a kind of hunting-horn said to be in use in England at the time. This suggestion does not seem to be a happy one; for if the reference be to the crescent-shaped horn, that instrument was in use in all countries at various periods before the 17th century, while if it be to the angular form, then a reproduction of such a horn should be forthcoming to support the statement.
The idea of bending the instrument is attributed to Giovanni or Giuseppe Ferlendis of Bergamo,  brothers and virtuosi on the oboe. One of these had settled in Salzburg, and both were equally renowned as performers on the English horn. They visited Venice, Brescia, Trieste, Vienna, London (in 1795) and Lisbon, where Giuseppe died. In this case we might expect the name to have been given in Italian, corno inglese; yet Gluck in his Italian edition used the French name already in 1767, when Giuseppe was but twelve years old. We must await some more conclusive explanation, but we may suppose that the new name was bestowed when the instrument assumed a form entirely new to the family of hautbois or oboes. The cor anglais was well known in England before 1774, for in a quaint book of travels through England, published in that year, we read that Signor Sougelder,  "an eminent surgeon of Bristol," was a performer "on the English horn."
The experiment of bending the cor anglais did not prove satisfactory, for the tube instead of being bored had to be cut out of two pieces of wood which were then glued together and covered with leather. Even the most skilful craftsman did not succeed in making the inside of the tube quite smooth; the roughness of the wood was detrimental to the tone and gave the cor anglais a veiled, somewhat hoarse quality, and makers before long reverted to the direct or vertical form.
 See Harleian MS. 2034, f. 207b, British Museum, in the third part of Randle Holme's Academy of Armoury, written before 1688, where an outline sketch in ink is also given.
 See J. Ecorcheville, "Quelques documents sur la musique de la Grande Ecurie du Roi," Sammelband intern. Musikges. ii. 4, pp. 609 and 625. Deeds exist creating charges for four hautbois and musettes de Poitou in the hand of King John, middle of 14th century, see p. 633.
 See Henri Lavoix, Histoire de l'instrumentation, p. 111; Gerber, Lexikon, "Giuseppe Ferlendis"; Robert Eitner, Quellen-Lexikon der Tonkünstler, "Gioseffo Ferlendis." Fétis and Pohl also refer to him.
 See Musical Travels thro' England (London, 1774), p. 56.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)