XXVI 



exhausted ; but it must now suffice only to mention some of his unpub- 

 lished and incomplete researches, of which many exist, and will be, it is 

 hoped, by some means made public. At the early part of his career, when 

 his thoughts were mainly directed to Acoustics, be endeavoured to inves- 

 tigate the causes of the differences of " timbre " or quality of tone in dif- 

 ferent musical instruments, presuming it to depend on the nature of 

 superposed secondary vibrations, and of the material by which they are 

 affected. This the writer has frequently, but in vain, urged him to com- 

 plete and publish ; but such was the fecundity of his imagination that he 

 would frequently work steadily for a time at a given subject, and then 

 entirely put it aside in pursuit, it may be, of some more important or 

 more practical idea that had presented itself to his mind. A short treatise 

 is in existence on the capabilities of his well-known wave-machine, in 

 which rows of white balls, mounted on rods, are actuated in two directions 

 perpendicular to each other by guides or templets with suitable curved 

 outlines ; by means of this machine many combinations of plane and 

 helical waves may be demoustrated, and especially those related to the 

 theory of polarized light. 



In furtherance of this subject he devised a new form or mode of geo- 

 metrical analysis, to which he gave the title of Bifarial Algebra, in which 

 both the magnitude and the relative position of lines on a plane surface 

 are designed to be represented by the introduction of two new symbols to 

 represent positive and negative perpendicular directions. The same prin- 

 ciple has also been extended to three dimensions, with a further proposal 

 of new symbols, under the name of Trifarial Algebra. On this subject 

 a brief treatise exists in manuscript. 



Amongst the subjects of his more recent but still incomplete in- 

 vestigations in Light and Electricity the following may be men- 

 tioned : — 



Colours of transparent and opaque bodies. 



Colours obtained by transmission and reflection. 



Absorption-bands in coloured liquids. 



Spectroscopic examination of light reflected from opaque and 



dichroic bodies. 

 Electromotive forces of various combinations. 

 Inductive capacities of various bodies. 

 Experiments on electro-capillarity. 

 Telegraph construction. 

 Construction of relays. 



Such of these as may be found sufficiently advanced to be of any scien- 

 tific value will probably be made public in a collective form. 



Charles Wheatstone was married on the 12th of February, 1847, and had 

 a family of five children, who survive him, Mrs. "Wheatstone having de- 

 ceased many years, He died in Paris on the 19th of October, 1875, whence 



