1 58 OF SLEEP. Sect. XVIII. 20* 



nious work lately publifhed by Dr. Beddoes. Who after la- 

 menting that opium frequently occafions reftleflhefs, thinks, 

 " that in mod cafes it would be better to induce fleep by the 

 abftrac*tion of ftimuU, than by exhaufting the excitability ;" and 

 udd$, " upon this principle we could not have a better foporific 

 than an atmofphere with a diminiflied proportion of oxygene 

 air, and that common air might be admitted after the patient 

 "Was alloep." (Obferv. on Calculus, &c. by Dr. Beddoes, Mur- 

 ray.) If it mould be found to be true, that the excitability of 

 the fyftcm depends on the quantity of oxygene abforbed by the ' 

 lungs in refpiration according to the theory of Dr. Beddoes, and 

 of M. Girtanner, this idea of fleeping in an atmofphere with lefs 

 oxygene in its compofition might be of great fervice in epileptic 

 cafes, and in cramp, and even in fits of the afthma, where their, 

 periods commence from the increafe of irritability during fleep. 



Sleep is likewife faid to be induced by mechanic preflurc on 

 the brain in the cafes of fpina bifida. Where there has been 

 a defeat of one of the vertebrae of the back, a tumour is protru- 

 ded in confequence ; and, whenever this tumour has been com- 

 preifed by the hand, fleep is faid to be induced, becaufe the 

 who of the brain both within the head and fpine becomes com- 

 pleted by the retroceflion of the fluid within the tumour. But 

 by what means a comprefhon of the brain induces fleep lias not 

 been explained, but probably by diminiming the fecretion of 

 fenforial power, and then the voluntary motions become fuf- 

 pended previously to the irritative ones, as occurs in mod dying 

 perfons. 



Another way of procuring fleep mechanically was related to 

 me by Mr. Brindfey. the famous canal engineer, who was 

 brought up to the bunnefs of a mill-wright ; he told me, that heT 

 had more than once feen the experiment of a man extending 

 himfelf acrofs the large Rone of a corn-mill, and that by gradu- 

 ally letting the ftone whirl, the man fell afleep, before the (toned 

 had gained its full velocity, and he fuppofed would have died 

 without pain by the continuance or increafe of the motion. In 

 this cafe the centrifugal motion of the head and feet muft accu- 

 mulate the blood in both thofe extremities of the body, aad thus 

 comprefs the brain. 



Laftly, we mould mention the application of cold ; which, 

 when in a lefs degree, produces watchfulnefs by the pain it oc- 

 cafions, and the tremulous convulfions of the fubcutaneous muf- 

 cles ; but when it is applied in great degree, is faid to produce I 

 fleep. To explain this erTecl: it has been laid, that as the veflcls 

 of the fkin and extremities become iirll torpid by the want of 

 the ftimulus of heat, and as thence lefs blood is circulated 



thr 



