the keys and the pull.downs, and are longer or shorter as may be required ; they are also parallel or fan-like, to suit their position.
Fig. 4 contains a few examples of pipes. There are two general descriptions of pipe, namely, the mouth, flute, or flue pipe, and the reed pipe, each containing several different species. ItIouth pipes have a mouth and lips like a flageolet ; they may be of wood or metal, and the upper extremity may be open or closed by means of a plug, called a temples, the effect of which is to lower the pitch a whole octave. The lower end is also closed with the exception of a narrow alit, which, in the pipes c and n, meeting a portion of the front well bevelled to a sharp edge, forms what is called the upper lip, or wind cutter. The foot of the pipe fits into the apparatus or cheat which supplies the pipes with wind. The blast from the narrow slit impinging on the upper Hp is thrown into vibration, which it imparts to the whole column of air iu the pipe, the result of which is a musical note, Fig. 2 represents what are called the horizontal bellows. A shows tho re.serroir; n, the deep frame through which the wind is taken ; o, the part moved in blowing, called the ; n n, the registrars, by which the equal rising of the reservoir is ensured : there are valves inside for receiving and retaining the wind, all of which are differently constructed by different builders.
no. 3 is a perspective view of a roller-board ; A A A, the board on which the rollers are fixed ; n, three pull-downs, explained below ; c c c, rollers centred at each end into amall blocks, in which they move ; there are also arms to each end, in front, connecting the rollers with the keys and the wind-cheat ; D, the levers which aro connected with depending for its pitch on the length of the column thus set in motion. The voicing of the pipe is performed by paring away the upper lip ; the upper part of the block is also toothed, so as to divide the plate of wind, or it would otherwise begin the note with a chirping noise. There are other precautions to be attended to, such as the width of the mouth. In metal mouth pipes, A D, the plate of wind is funned by the
edgo of the languette, by leaving a thin slit between the end of the languette and the lip. A is a metal open pipe ; F, the sounding part; a, the part called the languette, and n, the foot ; n is the same pipe, showing the mouth and the flattened part for voicing ; c is a front view of a stopped diapason pipe ; o is a section showing the arrangement of its construction ; z is the foot ; J is the block, and K is the cap. E is a section of the voice part of a reed pipe ; L, the foot ; sr, the mouth piece ; Iv, the reed ; and o, the tuning-spring. The pipe itself is made of a metal alloy of tin and lead ; the recd is brass, and the spring is soft steel wire, about a tenth of an inch in diameter. By pushing down or drawing up the tuning-wire, the free part of the tongue is made shorter or longer. The tube abovo the cone or foot is variously shaped, and on it depends the quality of tone in reed pipes, the pitch being duo to the length, thickness, and elasticity of the tongue. This form of reed pipe is the basis of all the others, their differences being more in shape than in principle. There is however a distinction between the free reed and the beating reed, as explained below. [See also HASuo nmi.] When speaking of the lengths of pipes, it is generally with reference to tuning or pitch C, which is one foot long; and all es below are doubled as we go from 1 to 2, 2 to 4, 4 to 8, 8 to 16, and 16 to 32; the last, although little used in this country, gives the highest rank to organs.
the pal-down, having a small screw and a leather button at one end, and a piece of hard bell-wire at the other ; the former is fixed to the lever, and the latter to the arm of the roller ; o is merely one end of the roller-board.
Fig. 6 represents a draw-atop, a trundle, and a lever, all of which are This Table shows the relative lengths and diameters of the open diapason, the principal, and the fifteenth stops, as high as a above middle C.