With the advent of polyphony the duties of the conductor increased. He often found it necessary to lead both visibly and audibly. Mendelssohn in a letter to his teacher, Zelter, gives a description of this manifold activity on the part of the conductor, indicating that it persisted even to the rather late date of 1830. Describing the papal choir in Rome, he writes:
“There is a chorus of priests (clericals) who sing only in the presence of the Pope or his representative. It numbers thirty-two regular members but they are seldom all present. The director personally sings with them, helping each part, sometimes singing the deepest bass and again jumping with astounding agility to the highest falsetto soprano.”
With the introduction of the mensural notation the old chironomic system ceased to have a reason to exist and the conductor instead of indicating every fluctuation of the melodic line, merely beat time at certain of the accented divisions of the phrase. This was done usually with a parchment roll of music in the hand, so that the singers and ever increasing number of instrumentalists could keep together.
The transition from the 16th to the 17th century brought about important innovations in music—the accompanied solo numbers of the opera came into being, the figured bass and bar line were introduced generally into choral and orchestral works. And, when in the course of the 17th century the demand that the conductor cease this mechanical beating of the time and give the tempo in a manner commensurate with the effect desired became insistent, the conductor took his place among the performers and lead the music from the clavicembalo. From this position he not only led the performance but also filled in the harmonies according to the figured bass. When the rhythm wavered, the first violin, whom we call the concertmaster, gave the beat.
Although this method of combined leadership (cembalo and first violin) was the one in general use during the 18th century, there were other modes of leading. Rousseau pokes fun at the Paris opera where much evil noise was made by pounding the floor with a stick in order to keep the musical forces together. It is a grotesque truth that Lully lost his life from an infection of the foot caused by a misdirected stroke of the cane with which he was beating time.
According to Gessner, Bach presided at the organ or cembalo while conducting and this seems to have been the method of Handel and Gluck likewise. Haydn conducted his London Symphonies sitting at the piano, more as a sort of public exhibition than as actual leader. The conducting was done by Solomon, the violinist.
In the meantime another revolutionary change had taken place in music itself. The general or figured bass playing clavier or cembalo was rendered superfluous by the incorporation of the full harmony into the orchestra itself. The only place where it held its own was in the accompaniment to the recitative.
Beethoven conducted his “Eroica” in the house of Prince Lobkowitz, 1804, standing at the conductor’s desk. It is assumed that he used a roll of sheet music, because in Germany the use of the baton was first introduced by Mosel in 1812.
Spohr gives us an interesting glimpse of Beethoven’s conducting methods. He says: “It was Beethoven’s custom to insert all sorts of dynamic markings in the parts, and remind his players of the marks by resorting to the most curious bodily contortions. At every ‘sforzato’ he would thrust his arms away from his breast where he held them crossed. When he desired a ‘piano’ he would crouch lower and lower; when the music grew louder into a ‘forte’, he would literally leap into the air and at times grow so excited as to yell in the midst of a climax.”
From about the year 1812 the use of the baton spread rapidly. We have records of Carl Maria von Weber using the baton in 1817 in Dresden, Mendelssohn in 1835 in Leipzig, and Spohr tells a most amusing anecdote of how the musicians of the London orchestra protested most vehemently when he first proposed to lead them with the magic little stick instead of playing the violin with them.