ON THE INFLUENCE OF WEATHER UPON MORTALITY. 301 



diseases, that, therefore, patients so suffering are not to be sent into any country 

 where meteorological instruments afford exactly or even nearly parallel readings. 

 In other words, in estimating the value of a foreign climate, or the different climates 

 of our own country, we are not to depend so much upon a comparison of the 

 meteorological data of the several places as upon the relations subsisting between 

 the meteorological data and the prevalent diseases and death-rate of one and the 

 same locality. Each spot of ground aspiring to the reputation of a health resort 

 must first have this problem solved for it, and then we may with greater safety 

 institute a general comparison. All that we can do in our present investigation 

 is to find out, if it be contained in our data, what is good and what is objection- 

 able in tlie climate of certain localities in Scotland, as evidenced by the general 

 death-rate, and by the mortality from several causes. This will not in any 

 way affect the character of the climates of Torquay, Bournemouth, Algiers, or 

 Rome, except in so far as there may have been a line of investigation pursued 

 in any of these places parallel with that now under consideration, so that a com- 

 parison may be instituted between the two ; for, to argue, that because a given 

 condition of temperature, atmospheric pressure, and humidity in Scotland is 

 accompanied by a certain ratio of mortality, therefore, meteorological data being 

 equal, the same death-rate will be observable in Torquay or Madeira, would be 

 most fallacious: all other things being equal, the death-rate would also coincide; 

 but it requires much more than mere meteorological analogy to establish such 

 a parallelism. 



But the present inquiry may serve another, and perhaps still more important, 

 purpose. By far the greater number of cases requiring medical treatment do not 

 involve the consideration of change of residence ; nevertheless, I venture to 

 assert that in all of them the weather plays an important part ; and it cannot 

 be otherwise than right for the physician to know whether he has, in the 

 atmosphere around his patient, a foe or an ally in the treatment of his malady. 

 In medical prognosis, a knowledge of the influence of weather is of essential 

 service ; and as an agent operating upon the therapeutic action of drugs, 

 weather forms a most important study. I do not pretend that this is by any 

 means an exhaustive inquiry ; nor have I strained my facts to meet any 

 so-called natural laws. On the contrary, the facts speak for themselves, some- 

 times making positive, sometimes negative assertions, and often enough hovering 

 between the two, leaving us as much in doubt as before, but with a stimulus to 

 deeper research into the influence of those numerous external agencies which are 

 under the immediate control of the Great First Cause of all. 



An inquiry into the causal relations subsisting between weather and disease 

 is beset with a multitude of difficulties. In the first place, we ought not to attri- 

 bute to the weather any effect upon the mortality of a given population, until we 

 have abstracted all other causes which might have operated in a similar manner, 



