36 TOPOGRAPHY 



inferred that sulphuretted hydrogen is the cause of 

 yellow fever (Niger expedition), I may here remark 

 that Major Tulloch observes, in his valuable medical 

 statistical report on Gibraltar, that the yellow fever 

 prevailed in epidemics, more in some situations than 

 others, particularly along the line wall facing the 

 sea. It is still more remarkable, and perhaps, does 

 away with any inference the above facts may have 

 induced, that the fever was not known to prevail on 

 board the different vessels at the same time in the bay 

 with the Caledonia and Formidable. The origin of 

 fever of nearly all kinds is still involved in mystery, 

 and that perhaps of none more so, than the fevers of 

 Gibraltar ; although apparently there are so few 

 visible sources of malaria, fevers of various kinds 

 prevail from year to year within the garrison, and 

 even well-marked cases of intermittent fever are 

 recorded by medical officers who have served there. 

 No unusual atmospherical phenomena were observed 

 during the epidemics of yellow fever ; the disease 

 could neither be traced to rain, heat, nor wind ; all 

 nature appeared to smile ; the flowers and plants 

 looked as beautiful as ever ; there was nothing unu- 

 sual in the atmosphere ; and the " sea rolled on as 

 it rolled before;" man alone seemed to wither and 

 die. Nor could any atmospherical cause account for 

 the recent prevalence of cerebral disease in almost an 

 epidemic form among the civil population of Gibraltar. 

 In the early part of the winter of 1843-4, a sin- 

 gular affection of the brain broke out among the 

 poorer classes of the civil population. This was at 



