Now that the School of Velocity has been acquired I can establish Trilby’s exercises, to be done once daily — in the morning if she is to perform or practice in the afternoon — or, if she has an evening performance, she may do them in the afternoon.
The trill should be practiced every day.
Trilby will do it in the coloratura range, the key of A flat.
The Contralto may do it in the key of F and the Dramatic Soprano in the key of G.
G would also be right for most tenor voices although F would do.
The Baritone can take the key of D and the basso C or B.
Just trill on the regular notes of the scale — the first and second, then the second and third, the third and fourth (this is a half tone trill of course) and so on up the scale.
The above exercises are written to be practiced by a high coloratura voice. A dramatic voice of soprano quality may begin them a note or two lower and not go up so high.
Each voice, of course, has its own limits which should never be pushed to their utmost.
The general range to be used by the different voices will be found under each exercise, but the extreme notes are given and not every voice, or in fact many voices will be able to take in all the given compasses.
Duval, John H. “The Secrets of Svengali on Singing, Singers, Teachers and Critics.” (1922).