626 PHILOSOPHICAL TRANSACTIONS. [ANNO 1800. 



motion by a bow applied nearly at % of the length from its end. Fig. 52, the method of tuning recom- 

 mended for common use. 



Fig. 53 ; A comparative view of different systems of temperament. The whole circumference repre- 

 sents an octave. The inner circle l is divided into 30103 parts, corresponding with the logarithmical 

 parts of an octave. The next circle n shows the magnitude of the simplest musical and other ratios, q 

 is divided into 12 equal parts, representing the semitones of the equal temperament described by Zarlino, 

 differing but little from the system of Aristoxenus, and warmly recommended by Marpurg and other 

 late writers, y exhibits the system proposed in this paper as the most desirable ; and p the practical me- 

 thod nearly approaching to it, which corresponds with the 11th method in Marpurg' s enumeration, ex- 

 cept that, by beginning with c instead of b, the practical effect of the temperament is precisely inverted. 

 k is the system of Kirnberger and Sulzer; which is derived from 1 perfect 3d, 10 perfect and 2 equally 

 imperfect 5ths. m is the system of mean tones, the sistema participato of the old Italian writers, still 

 frequently used in tuning organs, approved also by Dr. Smith for common use. s shows the result of all 

 the calculations in Dr. Smith's harmonics, the system proposed for his changeable harpsichord, but nei- 

 ther in that nor any other form capable of practical application. 



VIII. On the Effects which take place from the Destruction of the Membrana 

 Tympani of the Ear. By Mr. Astley Cooper, p. 151. 



Anatomists have endeavoured to ascertain, by experiments on quadrupeds, the 

 loss of power which the organ of hearing would sustain by perforating the membrana 

 tympani: dogs have been made the subject of these trials; but the results have not 

 been clear or satisfactory. Mr. Cheselden had conceived the design of making the 

 human organ itself the subject of direct experiment; and a condemned criminal was 

 pardoned, on condition of his submitting to it; but, a popular outcry being raised, 

 the idea was relinquished. Though denied the aid of experiment, the changes pro- 

 duced by disease frequently furnish a clue equally satisfactory. 



It often happens, that some parts of an organ are destroyed by disease, while 

 other's are left in their natural state ; and hence, by the powers retained by such 

 organ, after a partial destruction, we are enabled to judge of the functions performed 

 by those parts when the whole was in health. Guided by this principle, I have made 

 the human ear the subject of observation, and have endeavoured to ascertain the 

 degree of loss it sustains in its powers by the want of the membrana tympani ; a 

 membrane which has been generally considered, from its situation in the meatus, 

 and its connection with the adjacent parts by a beautiful and delicate structure, as 

 essentially necessary to the sense of hearing ; but which, as appears by the fol- 

 lowing observations, may be lost, with little prejudice to the functions of the 

 organ. 



Mr. P , a medical student aged 20, applied to me, in the winter of 1797, 



while he was attending a course of anatomical lectures, requesting my opinion on 

 the nature of a complaint in his ear, which had long rendered him slightly deaf. 

 On inquiring into the nature of the symptoms which had preceded, and of those 

 which now accompanied the disease, he informed me, that he had been subject 

 from his infancy to pains in the head, and was attacked, at the age of 10, with an 

 inflammation and suppuration in the left ear, which continued discharging matter 



