Now, if the reeds be left in this state and the organ be used for any length of time, it will be found that point B of the tuning wire will have risen upward until the abnormal strain upon the tuning-wire spring has been satisfied. In consequence of this, this particular note will be sounding flatter in pitch than it ought to do.
Conversely, if the portion of the tuning wire lettered C be slightly driven down, as in Figure 33, the retarding effect of the friction of repose at point B will cause the lower portion of the tuning wire to approach nearer the tongue than it should do.
If now this reed be left in this state, after the pipe has been used for some time and the tongue has been vibrating, it will be found that point B on this tuning wire will have traveled nearer to the tip of the tongue, in order to relieve the abnormal strain upon the lower portion of the tuning wire. Point A will then have resumed its normal position.
In Figures 32 and 33, the defective action of the lower portion of the tuning spring has been purposely exaggerated in order to make the point clear. This bending of the tuning wires, however, takes place to a much larger extent than most organ builders imagine. It is the chief reason why reeds fail to stand in tune.
When point A on the reed tuning wires is rigidly supported and held by force in its normal position, reeds can be made to stand in tune almost as well as flue pipes.
Figure 34 represents the Hope-Jones method of supporting the tuning wire at point A. It consists of having a brass tube T inserted in the block moulds before the block is cast. This tube T therefore becoming an integral part of the block itself. The inside bore of tube T is of such diameter that the tuning wire fits snugly therein.
In Figure 35 another method used by him for accomplishing the same purpose is shown. In this case a lug L is cast upon the block, forming, indeed, a portion of said block. The lower end of lug L is formed into a V, which partly embraces a tuning wire and supports it in such manner as to prevent improper movement of said tuning wire at point A.
When this method of construction is employed, the reeds are very much easier to tune, and, when once tuned, will stand infinitely better than reeds made in the ordinary way.
[1] Some organs have been made (notably that in Temple Church, London) with separate keys for the flats and sharps.