270 



THE FLORA OF THE INDIAN DESERT. 

 (JODHPUR AND JAISALMER.) 



BY 



E. Blatter, S.J., and Prof. F. Hallberg. 



Part VI. 



With 3 iMtes. 

 {Gontinued from page 47 of this Volume.) 



PART II. 



ECOLOGICAL NOTES. . 



1. Meteorology. 



The Indian Desert forms the east end of the greatest desert district of the 

 ■world, extending from the Atlantic coast of Africa and including the Sahara, 

 part of Arabia, S. Persia and Baluchistan. 



The chmate of our region is characterised by excessive drought, the rainfall 

 being scanty and irregular. The winter rains of Northern India rarely penetrate 

 into the region, and there is thus only one rainy season : that of the south-west 

 monsoon. 



We give a hst of meteorological data, obtained from the Government Obser- 

 vatory, Colaba. 



A few remarks are necessary to show the extreme irregularity of the rainfall. 

 The year 1917 was a record year, during which about three times as much rain 

 fell as the statistics of about forty years would lead one to expect. On the other 

 hand, not a single cent was registered at either Khabha or Ramgarh, Jaisalmer 

 State, in 1899. During the year in question 26 cents was received at Jaisalmer, 

 and the whole of this in April. In August 1881 ten inches fell in a single day 

 at Jodhpur. 



The cold season — from about the middle of November to the middle of March 

 — is characterised by extreme variations of temperature, and the temperature is 

 frequently below freezing point at night. During April, May and June the 

 heat is intense and trying, and scorching winds prevail with great violence, 

 sand-storms with great desiccating action being frequent. The relative humidity 

 of the atmosphere is always low. 



The meteorological conditions during our tour were very unusual, and for this 

 reason we think it worth while giving our observations in detail, in spite of their 

 fragmentary nature. We were held up for several days at Bhikamkor on account 

 of the Jodhpur -Phalodi railway line having been washed away in places by 

 the rain. 



In general, the region possesses a healthy chmate, except during the period 

 after the rains. As was to be expected, the year 1917 was particularly bad in 

 this respect. At the time of our visit, practically the entire population was 

 suffering from malaria. 



