Clafs II. i. 7. 2. OF SENSATION. 263 



the exuberance of it. Whence lefs fenforial power is exhaufted 

 in delirium, than at other times, as well as in fleep ; and hence in 

 fevers with great debility, it is perhaps, as well as the ftupor, 

 rather a favourable circumftance ; and when removed by numer- 

 ous blifters, the death of the patient often follows the recovery 

 of his underftanding. See Clafs I. 2. 5. 6. and I. 2. 5. 10. 



Delirium in difeafes from inirritability is fometimes preceded 

 by a propenfity to furprife. See Clafs I. I. 5. 12. 



M. M. Fomentations of the fhaved head for an hour repeat- 

 edly. A blifter on the head. Rifing from bed. Wine and 

 opium, and fometimes venefeclion in fmall quantity by cupping, 

 if the ftrength of the arterial fyftem will allow it. 



2. Delirium maniacale. Maniacal delirium. There is anoth- 

 er kind of delirium, defcribed in Se&. XXXIII. i. 4. which has 

 the increafe of pleafurable or painful fenfation for its caufe, 

 without any diminution of the other fenforial powers ; but as 

 this excites the patient to the exertion of voluntary actions, for 

 the purpofe of obtaining the object of his pleafurable ideas, or 

 avoiding the object of his painful ones, fuch as perpetual prayer, 

 when it is of the religious kind ; it belongs to the infanities de- 

 fcribed in Clafs III. i. 2. i. and is more properly termed hal- 

 lucinatio maniacalis. 



3. Delirium ebrietatis. The drunken delirium is in nothing 

 different from the delirium attending fevers except in its caufe, 

 as from alcohol, or other poifons. When it is attended with an 

 apoplectic ftupor, the pulfe is generally low ; and venefection 

 I believe fometimes deftroys thofe, who would etherwite have 

 recovered in a few hours. 



M. M. Diluting liquids. An emetic. 



4. Somnium. Dreams conftitute the mod complete kind of 

 delirium. As in thefe no external irritations are attended to, 

 and the power of volition is entirely fufpended ; fo that the 

 fenfations of pleafure and pain, with their aflbciations, alone ex- 

 cite the endlefs trains of our fleeping ideas j as explained* in 

 Sea. XVIII. on fleep. 



5. Hallucinatio vifus. Deception of fight. Thefe vifual hal- 

 lucinations are perpetual in our dreams ; and fometimes pre- 

 cede general delirium in fevers ; and fometimes belong to rev- 

 erie, and to infinity. See Clafs III. i. 2. i. and 2. and muft 

 be treated accordingly. 



Other kinds of vifual hallucinations occur by moon-light ; 



when objects are not feen fo diftinctly as to produce the ufual 



ideas affociated with them, but appear to us exactly as they are 



feen. Thus the trunk of a tree appears a flat furfac^, inftcad of 



- 



