J 841.] the Tides in the Indian Archipelago. 315 



The flood- tide, though with little force, runs to the N. E. and N.N.E. 

 the ebb-tide to the S. W. and S. S. W. either stream much dependent 

 on the wind. 



During the full strength of the monsoons, there appears long tides 

 to prevail, being only one flood and one ebb tide in twenty-four hours, 

 and as at Muntok and Onrust, during the change of the monsoons pe- 

 riodically, returning short tides took place twice in a day ; and during 

 this period they were all short tides of about six hours. At new and 

 full moon, the flood-tide comes in at about 6h. 20m. There is no daily 

 retardation of the flood-tide. It appears, as at Klampsis, on the 

 north coast of Madura, that during the W. monsoon the high water 

 takes place in the afternoon, and most likely the converse during the E. 

 monsoon. 



A mean number cannot be obtained here. 



The highest rise was during the 3 first months of 1840, 1. 60 ebb. 



The mean, 0. 75 



If we then compare the course of the tides at the different stations, 

 there is evidently observed a sensible difference of the tides without 

 the Archipelago, viz. of those on the West coast of Sumatra and 

 on the South coast of Java and of Amboyna, from those within the 

 Javanese sea. Here we are able to fix a certain mean number, by 

 means of which the time of high water is to be calculated, totally 

 different from the course of the tides within the Javanese sea. 



The former it appears follow the well known rules of the tides ; 

 there is twice in the day ebb and twice flood tide, and two tides take 

 place in the space of somewhat more than twenty-four hours in 

 the whole, depending on the moon's passing the meridian. 



Here we are able to fix a certain mean number, by means of which 

 the time of high water is to be calculated beforehand, totally different 

 from the course of the tides within the Javanese sea, which cannot 

 be traced to the common rules ; they rather are governed by the locali« 

 ty, the position of the sun, and the monsoons dependent on it. 



We may however state, that in the Javanese sea high water is 

 only once a day, and that besides these, long tides, or rather rises 

 and falls, which of more or less duration last together somewhat more 

 than twenty-four hours. Small or short tides prevail, whose very 



regular return depends on several causes, especially on the monsoons 



2r 



