NATURE 



{July 1 6, 1874 



THE RELATIONS BETWEEN HUMAN MOR- 

 TALITY AND THE SEASONS OF THE 

 YEAR 



A T tile anniversary meeting of tlie Scotiisii Meteorolbgi- 

 ^^ cal Society, a Very valuable paper Was read by i3r. 

 Arthur Mitchell; and the Secretary, ;\Ir. Alex. BucHan. 

 givilig an account of their investigations Oh the subject of 

 the influence of the seasons on human mortality at difTeient 

 rtges as caused by different diseases. The authors llave 

 tdlculated the weekly average death-rate of London fot- the 

 past thirty yeai's for thirty-one diseases, together with the 

 ftvei-ages of teitiperature, itloistUre, rain, &c. Consitlbring 

 thfe weather i2!tperienced in the course of the year as iHadc 

 lip Of sevel-al distinct climates differing from each Other 

 flfccording to the prevailing temperature and moisture; and 

 ttleit relations tO each other, the influence of these cliinates. 

 characterised respectively by cold, cold and dryness, 

 dl-yhess and heat, heat, heat and moisture, and cold and 

 moisture, on the mortality was pointed out. The '(veekly 

 illOttality from all causes and at all ages shows it large 

 feitess above the average from the middle of Novembetto 

 the middle of April, from which it falls to the minimum in 

 the end of May ; it then slowly rises, and on the third 

 ■tVeek of July shoots suddenly up almost to the maximlmi 

 of the year, at which it remains till the second week of 

 August, and thence falls as rapidly as it rose to a secondary 

 illinimum in October. Regarding the summer excess in 

 the death-l'ate, which is so abrupt in its rise and fall, it was 

 sho-Wn that it is wholly due to one section of the population, 

 Vi^. ififahts Under five years of age, none of the curves for 

 the other ages showing an excess in the death-rate from 

 all causes during the summer months ; and it was further 

 shown that the summer excess is due not only to the 

 deaths at one age, but to the deaths from one class of 

 diseases, viz. bowel complaints. The importance of 

 weekly averages in discussing these sudden fluctuations 

 of the death-rate to the changes of the weather was 

 pointedly referred to. Deducting the deaths from bowel 

 complaints from the deaths from all causes, the cui've 

 assumes a simple form, viz. an excess in the cold months 

 and a deficiency in the warm months. In other words, 

 the curve of mortality is dictated by the large number of 

 deaths from diseases of the respiratory organs. Tlie cur\e 

 of mortality in London has thus an inverse relation to the 

 temperature, rising as the temperature falls, and falling as 

 the temperature rises. On the other hand, in Victoria, 

 Australia, the curves of mortality and temperature are 

 directly related to each other — mortality and tempera- 

 ture rising and falling together. The character of the 

 curve of mortality in Victoria is impressed on it 

 by the deaths of persons below the age of five ; and 

 among such young persons the special diseases which 

 determine this influence are diarrhcea and dysentery. 

 This peculiarity arises from its higher mean temperaiure, 

 57°'6, as compared with that of London, 5o''o. In London 

 also during the hottest months of tlie jear the curves of 

 mortality and temperature rise and fall to;Tether, whereas 

 in Victoria the curves are throughout the whole year 

 directly related ; for though doubtless the deaths from 

 diseases of the respiratory organs fall as the temperature 

 rises, and rise as the temperature falU, yet the number of 

 deaths from these diseases is, owing to the comparatively 

 high winter temperature, never sufficiently large to in- 

 fluence the curve of the whole death-rate. The curves of 

 mortality for bronchitis and pneumonia at different ages 

 prove that the fluctuation is much less for pneumonia 

 than for bronchitis, and that the excess in both cases of 

 infant mortality is great, but not nearly so great as the 

 infant mortality for diarrhcea. The curves show that the 

 maximum mortality from the different diseases group 

 around certain specific conditions of temperature and 

 moisture combined, the general result of which, as regards 

 the principal diseases, may be thus roughly stattd : — 



Characler of Weather Maximum Mortality 



Colli Bronchitis, pneumonia, asthma, i:c. 



Cold and dry Brain-disease, convulsions, whooping- 



cough 

 Warm and dry Suicides, small-pox 



Warm and moist Diarrhcea, dysentery, cholera 

 Colli and moist Rheumatism, heart-disease, diphtlieria, 



scarlatina, measles, croup 

 The deaths from cancer and liver disease show no 

 distinct relation to weather. The period of the year least 

 marked by the occurrence of maximum mortality from 

 any disease is the warm dry weather which prevails from 

 the middle of May to the end of June. At this season the 

 only maximum is a well-pronounced secondary maximum 

 for measles ; and the maxima for suicides and small-pox, 

 which are, however, extended from the middle of April into 

 these months. Convulsions, teething, and atrophy and de- 

 bility have a secondary maximum in the warm moist 

 weather of July and August. In the United States, where 

 the heat is greater in summer, the secondary maximum 

 for convulsions is more distinctly marked than that of 

 London ; and in Victoria the summer maximum is 

 the only one that appears. The contrast offered by 

 certain curves to each other in all points is very 

 striking. Thus the curve (or whooping-cough begins to 

 rise above its average in the middle of December, attains 

 its maximum in March and April, and falls to the mini- 

 mum in September and October, whilst the curve for 

 scarlatina is exactly the reverse of all this, having its 

 minimum in spring and its maximum in autumn. It was 

 inferred from the general teaching of the curies, that if a 

 curve representing the progress of the death-rate from a 

 particular disease were given for a place whose climate 

 was known, though it might be impossible to name the 

 exact disease, it would be possible to say with a con- 

 siderable degree of certainty whether, for instance, the 

 nervous system, or the respiratory organs, or the abdo- 

 minal organs were involved in the disorder which caused 

 the deaths. 



CONFERENCE ON THE REGISTRATION OF 



PERIODICAL NATURAL PHENOMENA 

 '^"'HE Council of the Meteorological Society recently 

 -•■ resolved to organise a system of Observations of 

 Natural Phenomena, connected with the return of the 

 seasons, as well as of such branches of physical inquiry 

 as tend to establish a connection between meteorological 

 agencies and the development of vegetable life. 



As a preliminary to carrying out this intention they 

 invited the various Societies before which such subjects 

 most naturally come to nominate delegates to join a 

 committee by whom the whole question as bearing upon 

 agriculture, horticulture, &c., should be considered, and 

 to whom also any written communications should be sub- 

 mitted. 



The first meeting of this joint committee was held at 

 the Office of the Meteorological Society, 30, Great George 

 Street, on Thursday, July 2, when delegates were present 

 and promises of co-operation read from the Royal Horti- 

 cultural, Royal Agricultural, Royal Botanical, and other 

 Societies. After the subject had been fully discussed the 

 Rev. T. A. Preston, of Marlborough College, was re- 

 quested to prepare a list of plants to be c)bser^•ed, and 

 also to draw up a report on the same. Other gentlemen 

 were requested to prepare lists of insects, birds, and 

 animals. 



THE SPECTRUM OF THE AURORA 



BORE A LIS* 



'T' HE author's object in this paper is to make a smalt 



-'■ contribution towards the solution of the question, how 



the composition of the spectrum may be most correctly 



explained 'i 



• By the Kale Prof. .\. J. Angstrom. 



