274 



Cholera in Relation to Certain Physical Phenomena. [part i. 



of the July and August cases. Here maximum rainfall and maximum cholera correspond 

 accurately, as also the monthly maxima of relative humidity and cholera. The minima, 

 however, of these do not so closely tally. As usual in the non-endemic area, the 

 minimum temperature coincides with the minimum cholera, but the maximum of the 

 latter occurs when the thermometer is on an average six degrees lower than during 

 the hottest month. The maximum of the disease is seen to correspond almost exactly 

 with the minimum pressure, and vice versa. 



Mean monthly water-level [6 ^ 

 years] 1 



[Humidity = dotted curve] 

 Mean Kainfall [11 years]. 



Total Cholera [21 years] 



"l 



irsKsi 



■■gtanaaBPiMMKai 



■■■■II 



»9^^B^»*i>ca^B^Kai^^HiiHM^H 



-Water-level neai'est the surface. 



— A\'ater-]evel farthest from surface. 

 — 7U degrees of Humidity (dotted curv. 

 — tJO .. 

 -50 „ 

 —40 .. 

 -30 , 



= Lowest Rainfall, 



= Least Cholera. 



Monthly Temperature [8 years] 



= Lowest Temperature. 

 Diagram 15. — The average monthly Water-level, Humidity, Rainfall, Cholera and Temperature at Lucknow. 



The ivater-level has been registered by Dr. Bonavia at the Observatory for several 

 years, as also at the central prison some two miles distant, and it has been found that, 

 although a difference of 7 to 8 feet existed between the distance of the water in the 

 two wells from the surface, the fluctuation in the level of the water coincides very 

 closely. It is at its lowest in the month immediately preceding the maximum cholera 

 months, rises on an average about 4 feet between June and October, and then begins 

 to fall again. 



The soil within a few feet of the well at the Observatory is sandy, with a few 

 fragments of kunkur, and it appears not improbable that it is under the influence of 

 the adjoining river Groomtee. 



(5) Cawnpore. 



Returning to the banks of the Granges once more we come to the large civil and 

 military station of Cawnpore, which with the city close by furnishes a population of 



