SECT. XVIII. 20. OF SLEEP. 257 



Another method of "inducing fleep is delivered in 

 a very ingenious work lately publifhed by Dr. Bed- 

 does. Who, after lamenting thai opium frequently 

 occafions reftleflhefs, thinks, " that in moft cafes it 

 would be better to induce fleep by the abftraftion of 

 flimn'i, than by exhaufling the excitability;" and 

 adds, " upon this principle we could not have a 

 better foporific than an atmofphere with a diminifh- 

 ed proportion of oxygene air, and that common air 

 might be admitted after the patient was afleep." 

 (Obferv. on Calculus, &c. by Dr. Beddoes. Murray.) 

 If it (hould be found to be true, that the excitability 

 of the fyftem depends on the quantity of oxygene 

 abforbed by the lungs in refpiration according to the 

 the theory of Dr. Beddoes, and of Mr. Girtanner, 

 this idea of fleeping in an atmofphere with lefs oxy- 

 gene 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 in*, 

 creafe of irritability during fleep. 



Sleep is likewife faid to be induced by mechanic 

 preffure on the brain in the cafes of fpina bifida. 

 Where there has been a defect of one of the verte- 

 brae of the back, a tumor is protruded in confequence; 

 and, whenever this tumor has been comprefled by 

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

 whole of the brain both within the head and fpine 

 becomes comprefled bv the retroceffion of the fluid 

 within the tumor. But by what means a compref- 

 fion of the brain induces fleep has not been explain- 

 ed, but probably by diminifliing the fecretion of fen- 

 forial power, and then the voluntary motions be- 

 come fufpended previoufly to the irritative ones> as 

 occurs in moft dying perfons. 



Another way of procuring fleep mechanically was 

 related to me by Mr. Brindley, the famous canal en- 

 gineer, who was brought up to the bufinefs of a mill- 

 wright j he told me, that he had more than once 



feer* 



