210 On the Anatomy and Physiology of the Organs of the Semes. 



pressure is supplied^ not by a single surface, but by a semifluid coat of, it 

 may be, fifty miles thick. This will protect the bottoms of our continents, 



' Like feather-bed between a wall, 

 And heavy brunt of cannon-ball ;' 



SO I think we may sleep quiet in our beds, without fearing to have them 

 turned topsy-turvy by a jet of lava at new or full moon." 



ON THE ANATOMY AND PHYSIOLOGY OF THE ORGANS OF 

 THE SENSES. 



We propose, in the present and a few succeeding papers in this journal, 

 to consider the structure and functions of the organs of the senses, in man 

 and other animals ; and this we shall endeavour to do as concisely as is 

 consistent with clearness, and in as popular a manner as the introduction 

 of much unavoidable detail will admit of. 



But because the mere organ of a sense is by itself incapable of trans- 

 mitting its impressions to the mind, and because the assistance which the 

 senses derive from each other is in like manner dependent upon a distinct 

 medium, it will be necessary, to render their investigation satisfactory, to 

 include within it that of the medium by which they are connected, and 

 along which their impressions are conveyed to the sensorium, and the 

 mandates of the sensorium in turn reconveyed to the muscles by which the 

 requisite movements are performed — the nervous system. 



We are to consider then, the organs of the senses and the nervous sys- 

 tem, that is to say, the means by which we take cognizance of what is 

 going on in the world around us, and by the aid of which we are enabled 

 to turn to our present and future account the knowledge thus acquired. 



Inasmuch as it is only of late years that the method of reasoning by 

 strict induction has been generally applied in anatomical and physiological 

 science, it is only lately that the exceedingly minute details of the animal 

 frame have been thought worthy of investigation by anatomists in general; 

 and although the minutest examination of the organs of the senses has as 

 yet thrown very little light upon the composition of that part which actu- 

 ally receives impressions, yet the investigation has been much more suc- 

 cessful when directed upon the superadded parts of some organs, as for 

 instance, the eyej and the general conclusions arrived at have enlivened 

 the dry anatomical detail, and caused facts, formerly isolated and uninter- 

 esting, to become parts of a system, arranged like the stones of a finished 

 edifice, each concurring to the general support and stability of the whole. 



The value of the inductions to which a minute investigation of the organs 

 of the senses has led, has not however enriched anatomical and physiolo- 

 gical science so much as might have been expected; for the organ of only 

 one of the senses, that of vision, is at all well understood, and that because 

 the laws of refraction, dispersion, &c. and other properties of light having 



