��which was all that had previously been com- monly produced. For this purpose a means was devised for enabling the pipes standing in front (afterwards the Principal, Praestant, or Open Dia- pason), and the larger pipes in the side towers (subsequently part of the Great Bass Principal, or 32-feet Diapason), to be used separately and independently of the other tiers of pipes, which were located behind, and hence called the Hinter- satz, or ' hinder-position.' This result was ob- tained by introducing three claviers instead of one only ; the upper one for the full organ, con- sisting of all the tiers of pipes combined ; the middle one, of the same compass as the upper, and called ' Discant,' for the open diapason alone ; and the lower one, with a compass of an octave, from tj (Blj) to H (Blj), for the lower portion of the bass diapason. The result of this arrange- ment was that a change from forte to piano could be obtained by playing with the right hand on the middle manual and the left hand on the lower. It was even possible for the organist to strike out the plainsong, forte, on the Hintersatz with his left fist, and play a primitive counter- point (discant) with the right. Praetorius men- tions incidentally that the large bass pipes, which sounded the third octave below the unison, would have been scarcely definable, but being accom panied by the numerous pipes of other pitches in the general mixture organ, they became effec- tive. A rank of pipes sounding a ' third ' above the unison, like that mentioned by Seidel, and already quoted, might very well have been among these.
The claviers of the Halberstadt organ pre- sented several interesting features ; and being the earliest examples of chromatic keyboards known, are here engraved from Praetorius.
���The keys of the Halberstadt organ were made at a time when the five chromatic notes or
as we now call them, the 'sharps and flats'- were placed in a separate row from the ' naturals,' almost as distinctly so as a second manual of the present day. The keys of the upper (Hintersatz) and middle (Discant) claviers (Fig. 10) measured four inches from centre to centre, and the diatonic notes were ornamentally shaped and lettered, thus preserving the 'alphabetic' custom observed in the loth-century organ at Winchester, and de- scribed by Theophilus in the nth. The chro- matic notes were square-shaped, and had their surface about two and a half inches above that of the diatonic, were two inches in width, and one inch in thickness, and had a fall of about an inch and a quarter. The chromatic keys were no doubt pressed down by the three inner fingers, and the diatonic by the wrist end of the hand. The diatonic notes of the lower clavier (Fig. 1 1), eight in number, namely Ij (B fc, C, D, E, F, G, A, H (BtD, were quite differently formed, being square- fronted, two inches in breadth, and with a space of about the same width on each side. These keys were evidently thrust down by the left hand, by pressure from the shoulder, like handles, the space on each side being left for the fingers and thumb to pass through. This clavier had four chromatic notes, Cj, Eb, Fj, and G J, but curiously enough, not Bb, although that was the 'lyric semi- tone ' of which so much is heard long before.
The contrast between the forte and piano effect on the Halberstadt organ from the full organ to a single set of pipes must have been very violent ; but the experiment had the good effect of directing attention to the fact that a change, if less marked, would be grateful and use- ful ; for Seidel (p. 9) records that from this time instruments were frequently made comprising two manual organs, the upper one, interestingly enough, being named ' discant ' ; and he further gives it as his opinion that this kind of construc- tion probably led to the invention of Couplers.
He likewise mentions that large churches were often provided with a second and smaller organ ; and Praetorius speaks of primitive little organs which were hung up against a column in the church 'like swallows nests,' and contained twelve or thirteen notes almost or entirely diatonic, thus, B, C, D, E, F, G, A, B, C, D, E, F ; or
C, D, E, F, G, A, Bb,C, D, E, F, G, A. Dom Bedos relates that in the I4th century an organ was erected in the church of St. Cy- prian, at Dijon, which not only had two manuals, but had the choir organ in front. The front pipes were made of tin, those inside of lead ; there were said to be soundboard grooves, covered underneath with white leather ; three bellows 4 feet 7 inches long, and 2 feet i inch wide ; and an arrangement by which a continuous wind could be provided from one bellows only. This, how- ever, is manifestly the account of an organ which had received improvements long after its con- struction, such additions afterwards coming to be described as part of the original work.