probability of an analogy between the colours of a thin plate and the sounds of a series of organ-pipes; and observes that the same colour recurs whenever the thickness of the plate answers to the terms of an arithmetical progression, in the same manner as the same sound is produced by means of an uniform blast from organ-pipes which are different multiples of the same length.
11. Of the Coalescence of Musical Sounds.——In this section Dr. Smith’s assertion that the vibrations constituting different sounds are able to cross each other in all directions, without affecting the same individual particles of air by their joint forces, is minutely investigated and contravened.
12. Of the Frequency of Vibrations constituting a given Note.
13. Of the Vibrations of Chords.
14. Of the Vibrations of Rods and Plates.
Of the contents of these three sections no account will be here attempted, as they consist chiefly of experiments and demonstrations illustrated by diagrams.
15. Of the Human Voice—A technical description is here given of the formation of sounds by the configuration and inflexions of the different parts of the vocal organ. And it is intimated that by a close attention to the harmonics entering into the constitution of various sounds, much more may be done in their analysis than could otherwise be expected.
16. Of the Temperament of Musical Intervals.—After pointing out some imperfections in most of those who have treated this subject before him. the author suggests his own method of distributing the imperfection of the Scale, so as to produce a modulation that shall be found the least defective. And here he observes, as upon an average of all music ever composed some particular keys occur at least twice as often as others, there seems to be a very strong reason for making the harmony the most perfect in those keys which are the most frequently used; since the aggregate sum of all the imperfections which occur in playing, must by this means be diminished the most possible. and the diversity of the character at the same time accurately preserved.
Observations on the Effects which take place from the Destruction of the JtIembrana Tympani of the Ear. By Mr. Astley Cooper. In a Letter to Everard Home, Esq. F.R.S., by whom some Remarks are added. Read Feb. 6, 1800. [Phil. Trans. 1300, p. 151.]
The case to which we owe the observations contained in this paper, is that of a youth, who at the age of ten was attacked with an inflammation and suppuration in the left ear, which continued discharging matter for several weeks; and who after the space of about a twelvemonth had the same symptoms in his right ear, the discharge in both cases being thin and fetid, and conveying many small bones and particles of bones. On probing the ears when the youth was about twenty years of age, it was found that the membrana tympani
