Origin of the name "English Horn".
The French have always been great makers of musical instruments, particularly wind instruments.
At the beginning of the eighteenth century they took the crude hunting horn, a simple coiled pipe with a flared bell, and added interchangeable extra pieces of piping known as "crooks", and later valves, to make what they called the French Horn, a sophisticated brass orchestral instrument. The extra bits enabled the horn player to play in different keys according to the composers' wishes. The sound of a French Horn is generated by vibrating the lips in a mouthpiece, like a trumpet. The sound of the English horn is made by a double reed inserted directly into the mouth. The French Horn is made of metal; the English Horn is made of wood and with metal keys, often silver-plated, sometimes gold-plated.
Mid-eighteenth century saw the development of the Hunting Oboe, or Oboe da Caccia, into a more refined instrument, the Cor Anglais or English Horn. The Oboe da Caccia was a single wooden pipe with a double reed and a flared metal bell. It was a type of oboe, with a conical bore, but somewhat
bigger and thus deeper in pitch than the concert oboe. The instrument had finger-holes so it could play different notes, but the holes were far apart and the instrument was curved to make it easier to reach the holes. It had a pleasing sound and J. S. Bach wrote music for it in his St. Matthew Passion. Bach was fond of using the larger oboes in pairs, or 'choirs'.
It has been suggested that the name Cor Anglais is a corruption of "Cor Anglé" (meaning Angled Horn), a reference to a single bend in the instrument, but scholars have doubts about this. The earliest versions were curved, not angled. The angled ones came later, and because they had only one bend in the tube, instead of multiple bends that formed an apparent curve, they may have been acoustically more satisfactory, if rather unsightly. The name Cor, or Horn, could be an association of ideas with hunting e.g. hunting horn / hunting oboe. "Horn" originally meant the horn of an animal, such as a cow's horn, which could be hollowed out and made into a crude wind instrument. Nowadays the word 'horn' is used to describe almost any type of wind instrument. It could be that the cor anglais does sound a bit like a French Horn on certain notes, but not quite so pure (being a reed instrument, and actually a large oboe). There is no reason why the name of the instrument should be profound. The French may simply have found it practical to call this second development English Horn, the name French Horn already having been allocated. Possibly the giving of an exotic name to a new invention could make it seem more attractive. Other sources claim the cor anglais was invented in Poland in 1720, and that the name of the instrument meant "Horn of the Angels", but this meaning is not very likely ... surely not with an egg-shaped bell? Paintings of musical angels usually show them blowing a straight instrument with a flared bell like a trumpet, thus denying the principal defining feature of the cor anglais: the egg-shaped bell. The word 'anglais' might be a visual pun such as you find in some poetry. So it could mean 'English' or 'angled' or 'angelic' or any or all of them. Certainly the French did most to develop the instrument, particularly the Paris firm of Triebert. The name might well have emerged some years after the invention of the instrument.
If anyone finds a contemporary painting with an angel blowing an instrument with the egg-shaped bell or a bent oboe da caccia then please email me.
The Cor Anglais, like its ancestor the oboe da caccia, is a curved conical pipe with a double reed. The main difference from the oboe da caccia is the change in the shape and material of the bell, from flared metal to bulbous wood, and possibly the use of a smaller reed and a narrower bore for a more refined sound. As the practice increased of using metal keys to reach far-apart finger-holes, there was no longer any need for the the cor anglais to be either curved or angled, and it became straight, but with a small bent pipe at the very top to make it more accessible to blow. This pipe was called a "crook" and later a "bocal".