July 12, 1888] 



NATURE 



249 



was almost exactly 38 inches. Neither the birth-rate nor 

 the rate of increase has any distinct relation to the rain- 

 fall, but there are very evident indications of such a 

 relation as regards the rate of mortality. The first seven 

 years witnessed great fluctuations in the rainfall, and 

 these were almost exactly parallel in the death-rates, the 

 wettest years being those of greatest mortality. During 

 the last three years, on the other hand, the death-rate 

 increased slightly as rainfall diminished, and vice versd. 

 Amongst the principal causes of death, cholera and 

 small-pox vary enormously in their prevalence from year 

 to year, these diseases being of an epidemic nature ; but 

 the variations do not seem to be related in any way to 

 the rainfall. On the contrary, those from endemic 

 malarial fevers, represented by Fig. 8, follow the rainfall 

 variations very closely, and they are the chief factors in 

 the general mortality. 



In my former article, the death-rates from various 

 causes were compared with the prevailing meteorological 

 conditions, not year by year, but month by month. If a 

 similar method be adopted with the statistics of the ten 

 years now available, the conclusions arrived at in the 

 former paper are fully borne out as regards all their more 

 important points, only needing, in one or two instances, 

 slight modifications in detail. 



The next table gives the total mortality for each month, 

 computed as a rate per mille per annum, and also the 



rates for certain specified causes of death, which can in 



most cases be recognized by the recording agency. In 



1 computing these, the registered numbers have all been 



I increased by an allowance for omissions similar to that 



given above. 



Cholera. 



0-08 



Month. 

 January 

 February 

 March 

 April 

 May 

 June 



July 



August 



September 



October 



November 



December 



Year 



Total 

 Mortality. 



•• 3271 



•• 3085 



•• 30-94 



.. 38-26 



• 384O 



.'■ 36-29 



.. 31-41 



•• 38-67 



•• 45-27 



.. 58-60 



•• 54'67 



■• 4253 



Fevers. 



25^4 

 22-95 

 22 26 

 25'46 



25-55 

 24T2 



20-88 

 26-94 

 34*39 

 48-77 

 46-07 

 3612 



008 

 0-31 

 2-04 

 2-32 

 311 



2-59 

 3-o8 

 219 

 2 06 

 0-79 

 0-36 



Small- 

 pox. 



1-16 

 165 

 271 

 479 

 4'75 

 3-20 

 171 

 0-65 

 026 



0'12 

 Ol8 

 0-51 



Suicide. 

 0-032 

 0-036 

 0-062 

 0-087 



0*080 

 0083 

 0*078 

 0-077 

 0-084 

 0076 

 0-050 



0-034 



Wounds or 



Accidents. 



0236 



0-255 

 0276 



0-325 

 0366 

 0508 

 0-543 

 0-535 

 0532 

 0-404 

 0-276 

 0228 



3990 2998 1-58 i-8i 0066 0-374 



This table shows how utterly insignificant as causes of 

 death are cholera and small-pox, the two most dreaded 

 diseases, by the side of fevers, which account for three- 

 fourths of the total mortality. 



The monthly mean values of the three chief climatic 

 factors for the last ten years may be compared with the 

 preceding figures. They are : — 



Mean temperature 

 Range of temperature 



Rainfall 



Jan. 



Feb. March. April. May. June. July. August. Sept. Oct. 



Nov. 



Dec. Year. 



59*4 64-5 75-0 



27*5 27-4 30-0 



Inches. Inches. Inches. 



0-87 0-53 0-56 



These are computed on the average of the whole province, 

 exclusive of the higher hill stations. 



The relations of the rates of mortality to these climatic 

 causes will be best seen from the curves marked Fig. 9 

 to Fig. 16. The general death-rate, and that of fever 

 mortality, which follows it closely, have two maxima in 

 October and April or May, and two minima in July and 

 February or March. The secondary maximum in May 

 is a very important feature in the fever curve (Fig. 13), 

 but rises noticeably above the preceding minimum in 

 Fig. 12, which represents the general mortality, owing to 

 the influence of small-pox and, to a small extent, of 

 cholera. The fatal prevalence of fever seems to be 

 altogether uninfluenced by the temperature (represented 

 by Fig. 9), and its variations are almost exactly opposed 

 in phase to those of the rainfall, shown in Fig. 1 1 ; but 

 the maxima and minima nearly coincide in time with 

 those of the daily range of temperature (Fig. 10). These 

 statistics therefore confirm the general experience that 

 people are most subject to fever when the nights are 

 chilly and the days hot. If we neglect the secondary 

 maximum in the hot season, Figs. 11 and 13, represent- 

 ing rainfall and fever mortality respectively, will be 

 observed to be almost identical in form, except that the 

 latter is displaced three spaces to the right. This means 

 that malarial fevers are directly dependent on rainfall, in 

 their annual variation as in the variations from year to 

 year ; but it takes about three months in Northern India 

 for the malarial conditions brought about by the rainfall 

 (which probably depend on the growth and decay of 

 vegetation) to attain full development. Dr. Meldrum has 

 shown, in several of his annual reports, that in Mauritius 

 the highest fever mortality follows the maximum rainfall 

 at an interval of about two months, and in Northern India 

 a parallel rule seems to hold, except that the interval is 

 slightly longer. 



The meteorological conditions predisposing to cholera 

 are evidently heat and moisture, the disease being more 



prevalent than usual during the whole hot season from April 

 to October, and dying out in the winter. The cholera curve 

 (Fig. 14), which is drawn on a scale four times more open 

 than that for the total mortality, has two maxima in June 

 and August, and a secondary minimum in July. In most 

 years the first maximum falls in April or May, but it has 

 been thrown forward to June in the average for the last 

 ten years by the excessive mortality of last June, when 

 over 50,000 deaths from cholera were registered. 



Regarding small-pox (Fig. 15), shown on the same en- 

 larged scale as cholera, all the remarks in my former article 

 hold good. This disease is at a maximum in April and 

 May, and it diminishes rapidly during the rains, until it 

 almost dies out in October and November. The condi- 

 tions most favourable to its spread seem to be a high wind, 

 and very dry, or perhaps rather very dusty, air ; and the 

 number of fatal cases may be almost exactly represented 

 as a direct function of the wind velocity and the dryness 

 of the air. This result is completely in accordance with 

 all that is known about the cause and mode of propagation 

 of the disease. 



Fig. 16 gives the annual variation of the deaths by 

 violence, including under this head both suicides and 

 wounds. The curve is a very smoothly flowing one, with 

 a distinct annual minimum at the coldest time of the 

 year, a steady rise through the dry hot season, and 

 relatively high ordinates throughout the rainy season. 

 The scale of the curve is ten times more enlarged than 

 that of the cholera curve, or forty times larger than the 

 scale of total mortality or fever ; but though this 

 magnification renders the annual variation visible, it does 

 not reveal any irregularity except a slight increase in 

 September, when, owing to a long " break," or the pre- 

 mature cessation of the rains, the weather sometimes 

 becomes very much hotter than in July or August. This 

 September maximum is more distinct in the suicide ratios 

 than in those of deaths from wounds. It appears, there- 

 fore, that these fatalities from crime, instead of disease, 



