bass was so generally studied that any good musician would be able to reproduce, at least approximately, the intentions of the composer from such indications as the score supplied. But when, owing to the growth of the modern orchestra, the increased importance given to the instrumental portion of the music, and the resultant custom which has prevailed from the time of Haydn down to our own day of writing out in full all parts which were obbligato—i. e. necessary to the completeness of the music—the art of playing from a figured bass ceased to be commonly practised, it was no longer possible for whoever presided at the organ or piano at a performance to complete the score in a satisfactory manner. Hence arose the necessity for additional accompaniments, in which the parts which the composer has merely indicated are given in full, instead of their being left to the discretion (or indiscretion, as the case might be) of the performer.
2. There are two methods of writing additional accompaniments. The first is to write merely a part for the organ, as Mendelssohn has done with so much taste and reserve in his edition of 'Israel in Egypt,' published for the London Handel Society. There is more than one reason, however, for doubting whether even his accompaniment would succeed in bringing out the true intentions of the composer. In the first place, our modern orchestras and choruses are so much larger than those mostly to be heard in the time of Bach and Handel, that the effect of the combination with the organ must necessarily be different. An organ part filling up the harmony played by some twenty or twenty-four violins in unison (as in many of Handel's songs) and supported by perhaps twelve to sixteen bass instruments will sound very different if there is only half that number of strings. Besides, our modern organs often differ hardly less from those of the last century than our modern orchestras. But there is another and more weighty reason for doubting the advisability of supplementing the score by such an organ part. In the collection of Handel's conducting-scores, purchased some twenty years since by M. Schoelcher, is a copy of 'Saul' which contains full directions in Handel's own writing for the employment of the organ, reprinted in the edition of the German Handel Society; from which it clearly appears that it was nowhere used to fill up the harmony in the accompaniment of the songs. This must therefore have been given to the harpsichord, an instrument no longer in use, and which, if it were, would not combine well with our modern orchestra. It is therefore evident that such an organ part as Mendelssohn has written for the songs in 'Israel,' appropriate as it is in itself, is not what the composer intended.
3. The method more frequently and also more successfully adopted is to fill up the harmonies with other instruments—in fact to rewrite the score. Among the earliest examples of this mode of treatment are Mozart's additional accompaniments to Handel's 'Messiah,' 'Alexander's Feast,' 'Acis and Galatea,' and 'Ode for St. Cecilia's Day.' These works were arranged for Baron van Swieten, for the purpose of performances where no organ was available. What was the nature of Mozart's additions will be seen presently; meanwhile it may be remarked in passing, that they have always been considered models of the way in which such a task should be performed. Many other musicians have followed Mozart's example with more or less success, among the chief being Ignaz Franz Mosel, who published editions of 'Samson,' 'Jephtha,' 'Belshazzar,' etc., in which not only additional instrumentation was introduced, but utterly unjustifiable alterations were made in the works themselves, a movement from one oratorio being sometimes transferred to another; Mendelssohn, who (in early life) rescored the 'Dettingen Te Deum,' and 'Acis and Galatea'; Dr. Ferdinand Hiller, Professor G. A. Macfarren, Sir Michael Costa, Mr. Arthur Sullivan, and last (and probably best of all) Robert Franz. This eminent musician has devoted special attention to this branch of his art; and for a complete exposition of the system on which he works we refer our readers to his 'Offener Brief an Eduard Hanslick,' etc. (Leipzig, Leuckart, 1871). Franz has published additional accompaniments to Bach's 'Passion according to St. Matthew,' 'Magnificat,' and several 'Kirchen-cantaten,' and to Handel's 'L'Allegro' and 'Jubilate.'
4. The first, and perhaps the most important case in which additions are needed to the older scores is that which so frequently occurs when no instrumental accompaniment is given excepting a figured bass. This is in Handel's songs continually to be met with, especially in cadences, and a few examples follow of the various way in which the harmonies can be filled up.
At the end of the air 'Rejoice greatly' in the 'Messiah,' Handel writes thus,—
Mozart gives the harmonies in this passage to the stringed quartett, as follows:—
- See also Chrysander's 'Jahrbücher für Musikalische Wissenschaft,' Band I, which contains a long article on this subject.