249 



the rise in river levels. Prior to that date hydrographic changes 

 are slight. With falling levels and higher temperatures after 

 September 7 there is a slight recovery in Diaphanosoma from 189 

 per m. 3 on the 5th, to 1,053 on the 12th. 



In 1896 a well-defined heat pulse culminates August 10 at 86.5; 

 and Diaphanosoma, on August 8 at 14,260, with an abrupt depression 

 from 7,440, on July 28, to 160, on August 3, in flood waters. The 

 decline of this pulse from the maximum on the 8th to 440 on the 29th 

 is attended by a uniform decline in temperatures from 86 to 74.3 in 

 fairly stable hydrographic conditions, that is, declining river levels. 



In 1897 there are two well-defined summer heat pulses, one 

 culminating August 3 at 89, and the other September 14 at 83, 

 separated by a depression to 77.5 on August 24. The crest of the 

 Diaphanosoma pulse likewise has two apices, the first culminating 

 at 7,600 on August 10, followed, during the decline in temperatures, 



