It must be observed, that the crotchets in triple time are in general played by musicians slower than those of common time, and hence minuets are generally pricked in triple time, and country dances generally in common time.  So the verses above related, which are analogous to triple time, are generally read slower than those analogous to common time; and are thence generally used for graver compositions.  I suppose all the different kinds of verses to be found in our odes, which have any measure at all, might be arranged under one or other of these two musical times; allowing a note or two sometimes to precede the commencement of the bar, and occasional rests, as in musical compositions:  if this was attended to by those who set poetry to music, it is probable the sound and sense would oftener coincide.  Whether these musical times can be applied to the lyric and heroic verses of the Greek and Latin poets, I do not pretend to determine; certain it is, that the dactyle verse of our language, when it is ended with a double rhime, much resembles the measure of Homer and Virgil, except in the length of the lines.  B. Then there is no relationship between the other two of these sister-, Painting and Music?

P.  There is at least a mathematical relationship, or perhaps I ought rather to have said a metaphysical relationship between them.  Sir Isaac Newton has observed, that the breadths of the seven primary colours in the Sun’s image refracted by a prism are proportional to the seven musical notes of the gamut, or to the intervals of the eight sounds contained in an octave, that is, proportional to the following numbers: 

Sol.  La.  Fa.  Sol.  La.  Mi.  Fa.  Sol.  Red.  Orange.  Yellow.  Green.  Blue.  Indigo.  Violet, 1 1 1 1 1 1 1 9 16 10 9 16 16 9

Newton’s Optics, Book I. part 2. prop. 3 and 6.  Dr. Smith, in his Harmonics, has an explanatory note upon this happy discovery, as he terms it, of Newton.  Sect. 4.  Art. 7.  From this curious coincidence, it has been proposed to produce a luminous music, confiding of successions or combinations of colours, analogous to a tune in respect to the proportions above mentioned.  This might be performed by a strong light, made by means of Mr. Argand’s lamps, passing through coloured glasses, and falling on a defined part of a wall, with moveable blinds before them, which might communicate with the keys of a harpsichord; and thus produce at the same time visible and audible music in unison with each other.  The execution of this idea is said by Mr. Guyot to have been attempted by Father Cassel without much success.  If this should be again attempted, there is another curious coincidence between sounds and colours, discovered by Dr. Darwin of Shrewsbury, and explained in a paper on what he calls Ocular Spectra, in the Philosophical Transactions, Vol.  LXXVI. which might much facilitate