1835.] the strain of the wires in Pianos. 643 



The compensation for the strain of the wires above is effected bv 

 placing iron rods (two or three) in a direction parallel with the 

 strings, but below the bed of the instrument. The rods are fixed at 

 their extremities by a joint, to iron clamps, which are screwed to the 

 underside of the bed, and bolted at one end of the piano, through the 

 bed and block that holds the tuning pegs, and at the other, through 

 the bed, block, and plank. The extremities of the rods being thus 

 fixed, their power is obtained by drawing them over a stout wooden 

 bridge, placed at about two feet from the end. just below the keys of 

 the highest notes, and then drawn by adjusting frame, nuts, and 

 screws, as tight as is necessary ; as will, I hope, be distinctly shewn 

 by the accompanying plate and description. 



Fig. ] , is an elevation of a piano, which shews one of the rods, A, as 

 applied below, drawn by the adjusting screw C tight over the bridge 

 B. (The same letters apply to all the figures.) The bridge B is shewn 

 on a larger scale at fig. 3. By the drawing, fig. 1, the end of the 

 bridge B seems to present an unsightly appearance, but it is not so 

 in reality ; the rods crossing the bridge, at some distance from the 

 front, as at I in figs. 2 and 3 ; and so little are they visible, that they 

 would not be observed, unless attention was drawn towards them. 



The frame or adjusting nut C turns at one end on a knob or head, 

 formed on the end of the (short) rod, having a flat brass ring inter- 

 posed (to reduce the friction) between its head and the inside bearing 

 of the frame : the other end of the frame is made thick, as at figures 

 6 and 7, having a screw formed within it, to receive that on the end 

 of the rod. The screws are raised above the surface, and not cut into 

 the thickness of the rods. 



Fig. 2, represents the piano, turned upside down. AAA are the 

 reds, running in the same direction with the strings of the piano, 

 intended to be expressed by the shaded part between DDD. 



E E E, clamps with joints b, figs. 4 and 5, to receive the ends 

 of the rods, in which they are held by a small bolt. The clamps are 

 sunk in the wood, as shewn by the dotted line c c, are broader 

 towards their outer ends, d d, and thicker towards e e, that they may 

 oppose more surface in the wood, against the tension or drag of the 

 rods A. — F. figs. 2 and 6, is a clamp of another description, (it was 

 applied to one of the pianos operated upon ;) by it the bolts fixing the 

 ends of the three rods are connected : the two outer bolts GG, passing 

 through the end plank of the piano, and the centre one, H, through the 

 bed, block, and metal plate, on which the wires are fixed ; instead of 

 thus connecting the ends of the rods by one clamp, separate clamps 

 like EE, figs. 4 and 5 have been used : the clamps EEE, besides 

 4 o 



