The serpent was the bass of the old wooden cornett. As such, it predates the invention of keys and mechanics that make them work. It got its name from its curvy shape. No one would have been able to hold it or finger it if it were straight. As it is, the tone holes are placed according to where the player’s fingers can reach them and the right size for the player’s fingers to cover them. They are neither large enough nor properly placed for either optimum tone or intonation according to the laws of acoustics.
As the quotations below amply demonstrate, it was a useful instrument for some purposes, but only because nothing was any better. Most musicians whose views have come down to us seem to have disliked it. And yet it is the grandfather of both the modern tuba and the modern saxophone. (If you play neither of those instruments, go ahead and smirk!)
Canon Edme Guillaume: “The instrument gave a fresh zest to Gregorian Plainsong.”
Michael Praetorius (1571-1621): “Most unlovely and bullocky.”
Georg F. Handel (1685-1759): (On hearing the Serpent for the first time) “Aye, but not the Serpent that seduced Eve.”
Charles Burney (1726-1814): “In the French churches, there is an instrument on each side of the choir, called the Serpent, from its shape, I suppose, for it undulates like one. This gives the tone in chanting, and plays the bass when they sing in parts. It mixes with them better than the organ, (and) is less likely to overpower or destroy by bad temperament, that perfect tone of which only the voice is capable. The Serpent keeps the voices up to their pitch, and so is a kind of crutch for them to lean on.”
Marin Mersenne (1588-1648): “To accompany as many as twenty of the most powerful singers and yet play the softest chamber music with the most delicate grace notes.”
J. Viret: “A type of clumsy and unsightly cornett.”
Charles Burney (again): “The Serpent is not only overblown and detestably out of tune, but exactly resembling in tone that of a great hungry, or rather angry Essex calf.”
Hector Berlioz (1803-1869): “The essentially barbaric timbre of this instrument would have been far more appropriate to the ceremonies of the bloody cult of the Druids than to those of the Catholic religion. There is only one exception to be made – the case where the Serpent is employed in the Masses for the Dead, to reinforce the terrible plainsong of the Dies Irae. Then, no doubt, its cold and abominable howling is in place.”
Abbe Beaugeois: “The (Serpent) student needs a good ear, because many of the notes are only given by the lips.”
Marin Mersenne (again): “But the true bass of the cornett is performed with the Serpent, so that one can say that one without the other is a body without a soul.”
There’s more where these came from: Serpent Anecdotes & Quotes.