APPAKKXT UN ASTKON.iMV, 



AFPABITION. 



beanos fr.-w-l'-faJr to the eastward of the large star Fomalhaut, or 

 PwcU Australia, and hardly rises above the horiion in our hemi- 

 sphere. It is bounded by Cetus and Aquarius on the north, Fornax 

 flu-mica on the east, Pisds Australis on the west, and Phcrnix on the 

 sooth. There are no bright stars in this constellation. The following is 

 I enumeration of those which are visible to the naked eye : 



Number of Stan. 



6 4 



5-5 8 



28 



Total number of stars . . 40 



APPARENT (in Astronomy*. When it is necessary or convenient 

 to reduce an observed phenomenon, either by clearing it of tin 

 of any optical delusion, or substituting fur it the phenomenon v.lii.-li 

 uul<l have been observed at some more commodious station, that 



which U actually observed is called the apparent phenomenon. in 

 .iti-.ii to that which result* from correction or reduction, which i 

 called the real or true phenomenon. 



APPARENT MAGNITUDE, the angle under which any line 

 appears at the eye ; that is, the angle made by lines drawn from its 

 extremities to the eye. (MAUXITCUE. j 



APPARENT MOTION, the velocity and direction in which a body 

 appears to move, when the spectator himself is in motion, without 

 being consciuus of it. For further detail see MOTION. 



APPARITION. The mind affects the body ; the body affects the 

 mind ; and some insight may be obtained into the disordered states of 

 the mind, by considering the physical conditions which are necessary 

 to sound thought. 



It is not true, as is commonly supposed, that we see with the eye, 

 and hear with the ear, and taste with the tongue. The true seat of 

 these sensation* is the brain, and the eye, the ear, the tongue, are 

 organs adapted to receive impressions from external object*, which 

 impressions are transmitted from the organs by on appropriate appa- 

 ratus to the brain, whore they become sensations. When an object U 

 presented to an organ of sense, it produces a change in the nerves 

 of that organ. This change is conveyed by the nerves to the brain ; 

 a corresponding change is occasioned in the brain, and through the 

 brain in the mind; and it is this change in the mind which is 

 expressed by the term sensation. Ideas, on the contrary, are copies 

 of sensations, renovations of prior feelings, in general differing from 

 sensations in being less intense. 



The functions of the brain, then, are sensation, and, if the analogous 

 term be allowed, ideation, together with the action and re-action of 

 these two states on each other, known under the name of intellectual 

 operation. The main instrument by which intellectual operation is 

 carried on is what is termed association. It is a property of the mind 

 to combine and unite the sensations and ideas it receives in such a 

 manner, that, after this combination or union has been once formed, if 

 any one of these sensations and ideas be revived, the single sensation 

 or idea so revived will immediately call up to view all the sensations 

 and ideas that had previously been connected with it ; and this power 

 of association, as long as its action is sound, is observed to operate in 

 a uniform and determinate manner. For example, when sound, 



ciation excites ideas in a certain order, generally in the order of sen- 

 sation. Thus, if the sensations ABC were impressed upon the mind 

 in the order of these letters, n will re-excite not A, but c. Association, 

 when sound, operates by exciting ideas with a certain degree of 

 velocity. If the rapidity of the succession of the trains of ideas pass 

 beyond certain point, instead of distinct there is confused thought. 

 Association, when sound, operates by exciting ideas with a certain 

 degree of vivacity. Sensation is not produced, unless the external 

 object be applied to the organ of sense with a certain degree of force ; 

 while, if propelled against it with too great an impetus, instead of 

 specific sensation, it excites only pain. In like manner, unless the 

 trains of ideas recalled by association possess a certain degree of 

 vivacity, they present to the mind an indistinct assemblage of images ; 

 if. on the other hand, they are too vivid, they are equally incapable 

 of forming the dements of sound thought. 



In order that the brain may carry on these operations, that is, in 

 order that it may receive the impressions conveyed to it by the 

 nerves from the organs at sense, in order that it may convert these 

 impressions into sensations, and in order that it may duly combine 

 and revive them, it must be in a sound state. The chief agents which 

 maintain the brain in a sound state are its organic nerves, and iu 

 circulating vessel*, lake every other organ, the brain is maintained 

 in a healuiy condition by the process of nutrition. [NERVOUS STBTF.M, 



NAT. HIST. Inv.j Disease may take place in the substance of the 



brain, and this disease may 



be enumerated here, the slightest of which" may be inoompatil ' 



may assume a variety of forms far too great to 



the production of sound thought. If, on the other hand, the Bow of 

 blood through iu circulating reaels be deranged, the process of thought 

 may be equally disordered. Stop the flow of blood to the brain alto- 

 gether, insensibility will follow instantly ; fainting will supervene, and 

 this state will be quickly succeeded by death, unless the vital current 

 be re-admitted. Quicken the circulation beyond a certain point. 

 insensibility equally follows; and, though the preternatural velocity of 



the circulation should stop short of inducing insensibility, it may y.-t 

 ilixturb the ordinary process of thought in an infinite \.ui. \\ of modes. 



Now there is scarcely a single disease which is not copal -! 

 turbing, in a greater or less degree, the action of the organic nerves of 

 the brain ; but the maladies which most commonly and remarkably 

 disturb the functions of these nerves, are certain rlisoiisns of tin- allo 

 minal viscera, particularly of the alimentary canal, and more especially 

 of that portion of it which forms the stomach ; certain diseases of t he 

 liver, and of the mesenteric glands, and of the urinary and repi---: 

 organs. In like manner excitation or depression of the action of tin' 

 blood-vessels of the brain, beyond a certain j>oint. uniformly dU 

 sensation and all the mental operations. Striking illustration* of l.th 

 are afforded by the effect of many physical agents, as well as of natural 

 diseases. Of the first, the effects of the inhalation of niti-. i- \\->- 

 affords an example. \Vh.-n nitrous oxide is received into the lungs, 

 the pulse is increased in strength, fulness, and velocity. A corre- 

 sponding change takes place in the mental impressions. Sensation 

 becomes more vivid ; the sensibility to touch increases ; luminous 

 points dazzle the eye ; the hearing is more acute ; recolh 

 generally of a pleasing nature, and of uncommon intensity, pas* 

 rapidly through the mind. One individual compares his feelings, 

 under the influence of this gas, to those which he experience* wli.-n 

 witnessing an heroic scene upon the stage ; another likens them to the 

 emotions he felt when, on the occasion of the commemoration lu-M at 

 Westminster Abbey in honour of Handel, ho heard seven hundred 

 instruments playing at one time. 



The inhalation of ether, chloroform, and omylene, produces also 

 analogous effects. These substances have, in fact, been rmpl< 

 the extent of depriving the brain of it* consciousness, so that it is no 

 longer aware of external sensations, and suffers no pain. [A> 



The inhalation of malaria, the poison which produces fever, affords 

 an equally striking illustration of the modification of sensation, and of 

 all the subsequent operations of the mind, by a cause affecting the 

 nerves and blood-vessels of the brain. Febrile miasma is a depressing, 

 nitrous oxide a stimulating, agent ; the effect of the former on the 

 brain ought therefore to be the reverse of the latter, and, accordingly, 

 on receiving into the lungs the febrile miasma, the pulse becomes 

 oppressed and weak ; languor and lassitude pervade the limbs ; the 

 countenance becomes pale, the surface cold ; headache, giddiness, and 

 HIM n 'times vomiting supervene, while the mind is feeble, dull, dejected, 

 incapable of the effort of attention, and utterly unable to control ..r 

 even to connect the trains of gloomy and distressing images which 

 terrify the imagination. " Some circumstances had occurred," says a 

 physician who carefully observed the phenomena which attended the 

 progressive derangement of his own mind under the influence of fever, 

 " to render me anxious and dispirited ; of these I took an exaggerated 

 and gloomy view. I had been studying during several months with 

 unusual severity. One day in the cold weather of Januarv . 

 having been occupied many hours in the practical duties of my pro- 

 fession, I returned home fatigued. Great as was my bodily exhaustion, 

 the depression of my mind was still more remarkable. My head 

 ached, and unable to study or to attend to any professional engage- 

 ment, I lay on the sofa and attempted to read, chance having thrown 

 in my way the American novel called the 'Water Witch.' I ' 

 interested in the story, but the pain and confusion of my head 

 increasing, I requested a friend to read to me, my own eye continually 

 wandering from the page. The progress of the fever was rapid ; its 

 chief force fell upon the organ that had been recently over-cxciU-d. tin- 

 brain ; and delirium came on early, and somewhat suddenly. Immedi- 

 ately before I became decidedly delirious, I received an invitation to 

 the soirees given by the Duke of Sussex to the members of the Royal 

 Society. The friend I asked to return an answer expressive of my 

 regret that I should be unable to attend on account of illness, used, aa 

 I conceived, an expression not strictly correct : this verlial inaccuracy, 

 1 thought, was construed into wilful falsehood ; the matter was brought 

 before this assemblage of learned men, who unanimously declared t Int. 

 it ought to exclude mo from the society of honourable men, and that I 

 should no more be admitted amongst them. This aniiotinri -MM nt 

 was brought me from the palace, accompanied with martial music, 

 but of a more solemn and impressive kind than 1 had ever heard 

 before, in which was predominant the sound of Ix-lls, soft, and 

 as if of silver tone. Remonstrance was vain: the decision of which 

 I succeeded in obtaining a reconsideration, was confirmed ; this 

 confirmation was brought me in the same manner as the first announce- 

 ment, accompanied with the same kind of music, only still more sol.-nm 

 .uid impressive. I saw no person forming the lmd oi musicians, but 

 occasionally I heard very distinctly their measured step. I now 

 thought myself an abandoned and lost ln-ing; and the apprehension 

 that every one about me hated and sought occasion to destroy me. I....U 

 possession of my mind. My physicians, niv nurses, my dearest friends, 

 were in league with a malignant spirit, which assumed the shape of tin- 

 demon of the ' Water Witch." By an object of my tender affection, who 

 was anxiously watching over me, but in whom I now saw only the 



willing agent d the do n, I was betrayed, and through this trr 



the malignant spirit oM.-iim <l i-ntire possession of me. No sooner wan I 

 in the power of tin- d. n than she began to suggest to me the com- 

 mission of crimes abhorrent to my nature, and at last there fixed ti|>on 

 my mind the impression that I hod really been guilty of the crimes, l>y 



