VII. MUSICAL INSTRUMENTS. 163 



This instrument, of which the two key-boards are tuned in fifths, has a 

 comma at f interval one from the other, which serves to verify the theories 

 of musicians and natural ;philosophers upon the melodic or harmonic gamut. 



742c. Harmonium with German silver reeds, for diminishing 

 to the utmost changes of pitch due to alterations of temperature. 



Dr. Stone. 



743. Patent Double Trumpet, called Bi-Clairon. 



Franz Hirschberg, Breslau. 



The double trumpet (Bi-Clairon), constructed by the exhibitor, is described 

 by him as an equally interesting and practical invention. As the instrument 

 consists of two bell-mouths of different measure and construction, into which 

 the air can be admitted or from which excluded at pleasure through the soli- 

 tary valve, it has been rendered possible to produce by the same two kinds of 

 sounds, which, according to their sonorous colour, are now equal to the bugle 

 horn, now to the piston (or, also, to the cornet and the trumpet). The 

 instrument is particularly adapted for being used in concerts, inasmuch as by 

 the different sonorous colours more, " light and shade," consequently more 

 variation, is imparted to the execution, and, therefore, no band of musicians 

 should be without it. In a weak orchestral band, in which both bugle horn 

 and piston (respectively cornet and trumpet) are not always represented, this 

 instrument supplies the place of both. Its pitch is high C with B, and A low, 

 and is so constructed that the smaller bell-mouth can be screwed off, in which 

 case the instrument can be used as a common bugle horn (or cornet). 



744. Model of the Action of Grand Pianofortes. 



Messrs. Erard. 



745. Molineux's Patent Self-acting Escapement and 

 Check Repeater Action for upright Pianofortes. It com- 

 bines extreme simplicity, a firm and elastic touch, with freedom 

 from friction and great durability. Thomas Molineux. 



746. The first of the now generally adopted obliquely 

 strung upright Pianofortes, patented to Robert Wornum, of 

 the firm of Wilkinson & Wornum, in 1811. 



Messrs. PPbrnum fy Sons. 



The large factory in Oxford Street, in which this instrument was made, is 

 shown by an engraving within the lid. This factory was burnt down in 

 October 1812, and the partnership was then dissolved. In the following year 

 Robert Wornum made the first successful " Cottage " pianoforte, with vertical 

 stringing, to which he gave the name of " The Harmonic Pianoforte." He 

 accomplished this by discarding entirely the use of brass wires, and adopting 

 the closely-spun copper-covered strings in their stead. 



747. A Model of the Elastic Tie Action of the Piccolo 



Pianoforte, patented by Robert Wornum in 1826. 



Messrs. Wornum fy Sons. 



The mechanism of this pianoforte is still very generally adopted in France 

 and Germany, as well as in England. 



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