NATURAL THEOLOGY. 51 



from which it takes its name. It resembles also 

 a drum-head in this principal property, that its 

 use depends upon its tension. Tension is the state 

 essential to it. Now we know that, in a drum, 

 the pelt is carried over a hoop, and braced as oc- 

 casion requires, by the means of strings attached 

 to its circumference. In the membrane of the ear, 

 the same purpose is provided for, more simply, but 

 not less mechanically nor less successfully, by a 

 different expedient, viz. by the end of a bone (the 

 handle of the malleus) pressing upon its centre. 

 It is only in very large animals that the texture of 

 this membrane can be discerned. In the Philoso- 

 phical Transactions for the year 1800 (vol. i.) Mr. 

 Everard Home has given some curious observa- 

 tions upon the ear, and the drum of the ear of an 

 elephant. He discovered in it what he calls a ra- 

 diated mxuscle — that is, straight muscular fibres 

 passing along the membrane from the circum- 

 ference to the centre — from the bony rim which 

 surrounds it towards the handle of the malleus, to 

 which the central part is attached. This muscle 

 he supposes to be designed to bring the membrane 

 into unison with different sounds ; but then he also 

 discovered, that this muscle itself cannot act, un- 

 less the membrane be drawn to a stretch, and kept 

 in a due state of tightness, by what may be called 

 a foreign force — viz. the action of the muscles of 

 the malleus. Supposing his explanation of the use 

 of the parts to be just, our author is well founded 

 in the reflection which he makes upon it — " that 



