io2 SCIENTIFIC APPARATUS. 



They are used as the vibrators in harmoniums, and similar wind 

 instruments. Their great recommendation is their cheapness and 

 portability ; since a note can be thus obtained without the con- 

 junction of any sympathetic body or tube. They have, of course, 

 the necessary defect of being unsympathetic and feeble in compa- 

 rison with the organ. These defects are modified by the use of 

 channels in harmoniums, by suction in the American organ, and 

 by the use of shields and coverings for deadening and softening 

 the sound. 



Besides beating and free reeds, fresh combinations have 

 recently been effected. The gradual development of a new 

 condition of reed-power is illustrated by a collection of apparatus 

 exhibited, tracing its history from the earliest ^Eolian types. 



The simplest of these are found even among savages, who plant 

 their spears in the ground and lie listening to the -^Eolian sounds. 



A bow or a harp string was next found to have the same effect, 

 and thus various forms of the -^Eolian harp are recorded in history. 



Then came the more modern form claimed by Kircher, but 

 more properly attributed to an Englishman named Pope. Then 

 SchnelPs anemochord, and other devices, the particulars of which 

 are not recovered, making use of wind to set musical strings in 

 vibration more or less sustained. Then we come to a peculiar 

 arrangement of varnished ribbon or flat wire within a double 

 organ-pipe, introduced by Professor Robison for evoking ^Eolian 

 tones. Then a device for acting on one portion of the string 

 only, as by Green and Wheatstone. The next change was in the 

 adoption of a free reed tied by a silken thread to pianoforte wire, 

 as in the instrument devised by Pope ; then a reversion to the 

 string alone, with one portion flattened and spread out to the 

 whole force of the wind and preventing the lateral sway, as 

 designed by Julyan; then the flattened portion replaced by a 

 reed-tongue, with an attached wire in prolongation of length, as in 

 Farmer's invention ; then the reed-tongue separated from the pro- 

 longed string, and connected by a pin, as by Farmer and Hamil- 



