( 298 ) 



difference in the general mortality b\ comparing verj liol and very 

 cold siimmermonths. The principal causes however are different. 



We now lake as an example the mean mortality of infants al 

 Groningen over the whole period 1891 L905, expressed for every 

 month in percentages of one twelfth of the year-mortality; then we 

 find in round percentages (I.e. p. 74, Table XLIII B). 



April May June July Aug. Sept. Oct. 

 103 93 100 L10 L33 103 83 



We will compare these numbers with the mean monthly tempe- 

 ratures, and moreover with the number of days with excessively 

 high temperatures, which occurred during a similar period. In this 

 respect we think in the first place of' the days with maximum tem- 

 peratures above 25° C, for which the normals occur in the "Maand- 

 overzicht der weersgesteldheid in Nederland" 1 ). 



We thus find for the total number during the period 1*<I4 -1906. 



April May .bine July Aug. Sept. Oct. 



2 20 64 100 51 22 1 



whereas the mean monthly temperatures in the period 1891 — 1905 are 



8.6 13.0 16.6 18.4 17.6 14.7 9.6 



There is much more resemblance between 

 the form of the maxima in the first two 

 series of numbers than between those of 

 the first and third series, as is clearly 

 shown by fig. 1. {S mortality, Z number 

 of days with max. temp. > 25°, T mean 

 monthly temperature); but also for the 

 second series the epoch of the maximum does 

 not coincide with that of the first:. it Seems 

 as if there is a retardation of the mortality 

 as compared with the high temperatures. 

 In itself this does not look improbable. 

 Though the writer enters here a field where 

 he is scarceb entitled to a judgment, he 

 thinks he may risk the supposition, that 

 perhaps the high temperatures favour the 

 development of diseases which only after 

 a certain lapse of time cause death. If' this 

 be (he case, then a better agreement between 

 the fluctuations of temperature and mor- 



ij (.Monthly weather review in the Netherlands) Publ. N°. <J4 Kon. Ned. Meteor. Inst. 



