2S60.] 



Memorandum on the Irawadi River. 



175 



memorandum on the Irawadi River, ivith a monthly Register of its 

 Rise and Fall from 1856 to 1858, and a measurement of its mini- 

 mum discharge. — By Lieut. -Col. A. Cunningham. 



Under instructions from Major Phayre, Commissioner of Pegu, a 

 daily register of the rise and fall of the river Irawadi has been kept 

 at Thayetmyo, Prome and Henzadah, from the highest flood in 1856 

 to the maximum rise in 1S58. The results of these observations at 

 Prome and Henzadah are embodied in the accompanying diagrams, 

 which show the actual height of the river at each place on every 

 tenth day throughout the period of observation. The Thayetmyo 

 register has been omitted, because the first twelve months' observa* 

 tions are palpably erroneous, and cannot now be corrected, whilst 

 the last twelve month's observations correspond so closely with those 

 taken at Prome, that I did not think it worth while to draw up an- 

 other diagram for a single year. 



2. The Irawadi generally attains its lowest level about the end 

 of March, when a slight rise takes place for a week or ten days until 

 the middle of April, after which time for about a month, the river 

 becomes stationary, occasionally rising and falling until the first 

 week of May. This is the usual period for the setting in of the 

 monsoon, and the river continues steadily to rise, with but few checks 

 until August, when it attains its maximum. The actual period at 

 which the river has gained its greatest height during the last three 

 years has ranged from the end of July to the beginning of September. 

 The following are the dates of maximum at the three places of 

 observation : 



+ 



Thayetmyo. Pbome. 



Henzadah. 



1856 



1857 

 1858 



29th July. 



10th August. 



4th September. 



30th July. 

 10th August. 

 5th September. 



30th July. 



11th August. 



1st September. 



2 a 2 



