43 On Malaria, 



within the last years, that the intermittent season runs into the 

 remittent one, or there is no midsummer interval of freedom 

 from disease ; while it has also happened, and in some parts of 

 England in this last year, that what would have been intermit- 

 tent fever in other years has been remittent ; or the common 

 fever has occupied the whole summer, continuously, even from 

 March to November, as is the case in the worst regions of 

 southern Europe. 



Now, under these exceptions, which I was bound to explain, 

 the commencement of intermittent, or of vernal ague, may be 

 fixed about the middle or end of March, and its termination 

 similarly in May ; while that of remittent may be placed in the 

 beginning of August, and its termination with the middle or 

 end of October. How these periods may otherwise be affected 

 by the more or less insalubrious nature of the district or place, 

 will easily be judged of by those who will reflect for them- 

 selves on what I dare not explain, lest I should infringe too far 

 on my limits. All else that I can venture on, as to this part of 

 the question in hand, relates to the effects of the different 

 times of the day on the production, propagation, or influence 

 of malaria, and it is one which is of no small importance in a 

 practical view. 



AVhether the changes as to temperature and moisture which 

 occur within the space of twenty-four hours, affect the produc- 

 tion or propagation of malaria^ I will not here inquire minutely, 

 from the fear of prolonging this very limited paper ; but the 

 general facts, as to its effects, are these : If we commence with 

 the sun on the meridian, there appears, even in the worst cli- 

 mates, very little hazard of fever ; while in Italy, it is believed that 

 there is, generally, little or no hazard, except in some peculiarly 

 pestilential places, and under particular kinds of inattention or 

 neglect. Either the malaria is decomposed or destroyed by 

 the heat, or else the air from its dryness ceases to be a con- 

 ductor; but as evening approaches, its influence becomes pow- 

 erful and dangerous, being supposed most generally to extend 

 all through the night; while in some parts of that country it is 

 a popular belief that it terminates before midnight, or with the 

 precipitation of the atmospheric moisture. Whether this last 

 opinion is true or not, the general fact explains the popular 



