I acknowledge, however, that many chorus-masters, or sub-conductors of orchestras, are sometimes of real utility, and even indispensable for the maintenance of unity among very large masses of performers. When these masses are obliged to be so disposed as that one portion of the players or chorus-singers turn their back on the conductor, he needs a certain number of sub-beaters of the time, placed before those of the performers who cannot see him, and charged with repeating all his signals. In order that this repetition shall be precise, the sub-conductors must be careful never to take their eyes off the chief conductor's stick for a single instant. If, in order to look at their score, they cease to watch him for only three bars, a discrepancy arises immediately between their time and his, and all is lost.
In a festival where 1200 performers were assembled under my direction, at Paris, I had to employ four chorus-masters, stationed at the four corners of the vocal mass, and two sub-conductors, one of whom directed the wind-instruments, and the other the instruments of percussion. I had earnestly besought them to look towards me incessantly; they did not omit to do so, and our eight sticks, rising and falling without the slightest discrepancy of rhythm, established amidst our 1200 performers the most perfect unity ever witnessed.
With one or more electric metronomes, it seems no longer necessary to have recourse to this means. One might, in fact, thus easily conduct chorus-singers who turn their back towards the chief conductor; but attentive and intelligent sub-conductors are always preferable to a machine. They have not only to beat the time, like the metronomic staff, but they have also to speak to the groups around them, to call their attention to nice shades of execution, and, after bar-rests, to remind them when the moment of their re-entry comes.
In a space arranged as a semicircular amphitheatre, the orchestral conductor may conduct a considerable number of performers alone, all eyes then being able to look towards him. Nevertheless, the employment of a certain number of sub-conductors appears to me preferable to individual direction, on account of the great distance between the chief conductor and the extreme points of the vocal and instrumental body.