VOL. XIV.] PHILOSOPHICAL TRANSACTIONS. 33 



cipally done by a vast enlargement of the flancks and demigorges, so as to be 

 capable of 3 very large batteries, one over another, and sometimes a cavalier at 

 top, all which in some figures may hold 100 or 120 cannon, sufficient to dis- 

 mount any battery that may be raised on the counterscarp. 



Two remarkable Cases relating to Vision, communicated by Wm. Briggs, M.D. 

 Fellow of the College of Physicians, and Physician of St. Thomas's Hospital. 

 N° 159, P- 559. 



I received some time since an account of a remarkable case of vision, from 

 Dr. Parham, physician in Norwich ; in 2 letters, of which the following are 

 abstracts. 



First letter: ' I was lately in SufFolk, and there met with a curious and rare 

 case relating to vision, A gentleman gave me the history of it, and his servant 

 who was the subject of it, being then in the house, I had an opportunity of 

 fully informing myself. 



The young man may be near 20 years of age, and during the day time has as 

 good a sight as any of the family, if not better ; he distinguishes any object at as 

 great a distance; sees either near at hand or far off, or at any intermediate dis- 

 tance, as well as any person ; but when twilight once sets in, he is as blind as a 

 beetle; sees nothing; runs against gates, posts or rails, and cannot without 

 great difficulty direct himself. Neither does this seem to be from the want of 

 any vigorous influence from the rays of the sun ; for when he is at home and 

 in the house, he tumbles over stools, runs his head against doors, and can 

 hardly see or direct himself either by the greater or less lights of the fire and 

 candle; but commits pleasant mistakes, is apt to compliment your feet as 

 readily as present you steadily with a glass of wine, runs his head against his 

 master's foot when he is to pull off his boots, &c. 



There is no disease in the organ that can be observed ; no vertigo or distemper 

 in the head, to interrupt or any way intercept the spirits in their motions ; but 

 to all appearance the fabric of the organ is very true and exact, I observed the 

 eye both by day and night, but could perceive no fault in any part; neither do 

 I think the suspicion well grounded, that he sees better than others by day- 

 light, becaiise of the vigour and plenty of rays, for then he might have the 

 same benefit from good fires and candles to invigorate the organ, and contract 

 the pupil ; but it seems rather to depend on some of the humours, though I 

 cannot tell at present on which, having not had time since to consider of it. I 

 tried him with spectacles for a variety of sights, but they did him no service by 

 either lights." 



VOL. III. F 



