PARTICULARITIES OF THE STANHOPE MONOCHORD. 



First. The wire is not made either of brass 

 or of iron, but of steel, which is very far su- 

 perior. For, steel wire does not keep con- 

 tinually lengthening-, as brass and iron wires 

 do when they are stretched considerably. 



Secondly. The wire in this monochora does 

 not, as usual, pull downwards on the bridges, 

 but the whole wire forms one straight and 

 horizontal line, by which means the moveable 

 bridge, which determines the exact length of 

 the Wire, can be moved without altering the 

 tension of the wire. This is not the case 

 when the wire pulls downwards on the bridges. 



Tliirdly. Trie ends of the wire are not 

 twisted round the two stout steel pins which 

 keep it stretched ; but, each end of the wire 

 is soft-soldered in a long groove formed in a 

 piece of steel which goes over its correspond- 

 ing pin. This is a great improvement. 



Fourthly. One of those two steel pins is 

 strongly fastened on a brass slider which is 

 moved by means of a screw with very fine 

 threads, which screw has a large micrometer 

 head minutely divided on its edge, and a cor- 

 responding nonius; so that, the tension of the 



A MOST CURIOUS AND IMPORTANT 



There is a second steel wire, equal in size, 

 which may be placed occasionally on this 

 monochora. The reader may form an idea of 

 the prodigious accuracy of this instrument, from 

 the following experiment, which I have often 

 repeated in the presence of different persons, 

 to the great astonishment of them all. 



I begin by stretching the two wires with a 

 degree of tension so precisely equal, that no 

 beating is audible between them. In this ex- 

 periment, I have generally made the length 

 of each wire exactly twenty inches between 

 the bridges ; and each wire has been so 

 stretched as to yield the same sound as that 

 note which is commonly called the first 

 bass G; but any other note would do. 



By means of a fine screw, which has fifty 

 threads to the inch, and which has a micro- 

 meter head very finely divided on its edge, 

 I can move the slider on one of the bridges 

 to such a minute degree, as to lengthen or 



STANHOPE TUNING-GLASSES 



wire may be adjusted with the greatest pre- 

 cision, in order to obtain its exact pitch. 



Fifthly. A slider is fixed across the top of 

 the moveable bridge, and is moved by means 

 of another screw with very fine threads; so 

 that, the length of the wire may be regulated 

 with the greatest nicety in all cases. 



Sixthly. The above mentioned slider which 

 is on the top of the moveable bridge is ad- 

 justed to the steel rod or scale, not hy sight, 

 or by the coincidence of lines; but by means 

 of mechanical contact against projecting pieces 

 of steel firmly fixed on that steel scale, which 

 method is incomparably more correct. Those 

 projecting pieces are fixed on that scale at 

 the respective distances specified in the mono- 

 chord table, no. i. See page 21. 



Seventhly. Each bridge carries a metallic 

 finger which keeps the wire close to the top of 

 the bridge whilst the wire is made to vibrate. 



Eighthly. The vibrations of the wire are 

 produced by touching it with a piece of cork, 

 with the same elastic force, and on the very 

 same spot each time, namely, at the distance 

 of one inch from the immoveable bridge. 



EXPERIMENT. 



shorten that wire as little as the one hundred 

 and eightieth part of the one hundredth of an inch, 

 without altering its tension. Such a very small 

 alteration in the length of one of the two 

 wires invariably produces an audible beating 

 between them. And not only the beating may 

 be heard; but, what is remarkable, it may 

 likewise be distinctly felt. The best way to 

 feel it, is to support a small piece of steel 

 wire, about two inches long, on the sound- 

 board of the monochord, with one of the 

 finger nails. If the lower end of that piece 

 of wire be semi-spherical ; if its upper end be 

 pointed ; and if that pointed end be applied 

 to the new or tender part of the nail ; then, 

 the beating will be felt very sensibly. 



This beautiful experiment clearly proves 

 how perfectly unisons may be tuned ; since, 

 the smallest deviation in an unison is thus dis- 

 tinctly perceptible. This leads me to my next 

 discovery. 



Some persons have had timing-forks adapted 

 to the pitch of the different notes. One fork, 

 to the pitch of C ; another, to the pitch of G, 

 &c. The timer has then nothing to do but to 

 tune ail the Cs of the piano-forte, organ, or 

 other keyed instrument, to the C fork; all 

 the Gs to the G fork, &c. This is perfectly 

 good in theory. But there is, in practice, an 

 objection to forks which is not generally known. 

 It is this. Out of a hundred forks, there is, 

 perhaps, not one which has not a beating in it, 

 when it is struck. How, then is it possible 

 to tune an instrument accurately by means 

 of forks which do not yield a pure or single 

 sound? It is, however, frequently practicable 

 to get rid of the beating in a tuning-fork, by 

 very carefully filing the two leps so as to 

 make them exactly alike throughout. But, 

 this requires much more attention than is 

 likelv to be commonly bestowed. 



I have contrived a tuning instrument which 

 is far superior. It consists of thirteen slips of 

 plate-glass; each of which is exactly six inches 

 long, by two inches in breadth. They are 

 tuned respectively one perfect octave higher 



than the pitch of the keys in the monochord 

 table, no. i. For, by varying the thickness, 

 I can tune one slip to C ; another, to G, &c. 

 The thickness of the slip which yields the 

 sound of the middle C is about nine hundredths 

 of an inch ; and the thickness of the slip which 

 yields the sound of the first treble C is about 

 eighteen hundredths. Those two Cs are the 

 two extremes. Each slip yields a sound which 

 is extremely pure. The same brass support, 

 which terminates in three pointed corks, serves 

 for each slip in succession. Each slip is 

 similarly placed on that support, is struck by 

 the same cork hammer, witn the same elastic 

 force, and on the corresponding spot, each 

 time. By means of this simple tuning ap- 

 paratus, which is pitched to my new and 

 improved temperament, any careful per- 

 son, with a moderate ear, can tune an in- 

 strument perfectly, and better perhaps than 

 the best tuner could do without this admirable 

 assistance, which to persons in the country 

 may be very useful. And, to professional 

 tuners, this permanent and portable tuning 

 instrument will be extremely convenient. 



STEREOTYPED AND PRINTED BY A. WILSON, DUKE STREET, LINCOLN'S INN FIELDS. 



(24.) 



