46 Dr. Mac Culloch on Malaria on Ship-board. 



typhus, every one knows : to prevent marsh fever the rules 

 are equally obvious ; since it is to avoid the lands or circum- 

 stances which produce them. The object of the Essay on 

 Malaria was to describe those, for the purpose of prevention ; 

 but that knowledge will become effective only when the dis- 

 tinctions between the two kinds shall be truly and invariably 

 drawn, and when the people and their physicians shall have 

 learned to admit, first, that fevers have a cause, and next, that 

 the cause of those fevers, which are not typhus, is marsh 

 miasma or malaria. How this question applies to ships, also, 

 to the subject especially in hand, must be peculiarly apparent. 



But the basis of the whole inquiry, the nature and causes of 

 fevers, is so much in want of elucidation, and that elucidation 

 is so necessary to a right understanding of the main question, 

 that I must yet offer some remarks on this subject : while I 

 also conceive that it will, in itself, not prove an uninteresting 

 one to popular readers, thus treated ; since, while they do 

 interest themselves much about it, they are in a state of great 

 confusion of mind relating to the whole subject. If people 

 will think and act for themselves on the subject of medicine, 

 and if they will control their physicians, it is, at least, of 

 importance that they should think correctly. That, on this 

 question of the distinctions and causes of fevers, even Physic 

 itself is not very clear at present, I hope to show : while, 

 whether I succeed in convincing my own profession or not, it 

 is, at least, my duty to state my own opinions, and the reasons 

 on which they are founded. 



I need not touch on the causes of contagious fever ; they 

 are known, and not disputed. The question is, whether there 

 is any other cause of fever besides those, except the application 

 of marsh miasma, or malaria. It appears to me that no others 

 have, at least, been proved ; and if this be so, then it also 

 follows that there are but two species of fever, contagious and 

 marsh fever. For the purpose of establishing this merely, an 

 inquiry into the causes of fever will be valuable ; but it will be 

 directly useful in another way. If, of any effect or effects, there 

 are more causes than one, our power over these is checked or 

 diminished : should we even suspect more causes than one, 

 and without proving them, our confidence in our philosophical 



