1844.] MARINE OBSERVATORY. 211 



day it was calm until long after high water, and as it 

 eventually proved that the night tide rose higher than that 

 of the morning, it was fortunate that we had taken advan- 

 tage of the strong breeze, as our entry might otherwise have 

 been delayed some days, and incurred much labour and ex- 

 posure during the heat of the forenoon. As the receding 

 tide bared the surrounding banks, nothing presented but 

 very loose mud, and we were therefore rather at loss for a 

 spot to obtain observations, for securing the position of 

 the mouth of this almost unknown river. I have had 

 but too much reason to admit, that necessity sharpens our 

 wits, and as in this case we were successful, and it may 

 afford a useful hint to others similarly situated, I will 

 mention the method by which we overcame this diffi- 

 culty. The mangrove trees which stud the coast-line, 

 were very large, and grew weh 1 out in a depth of three 

 feet at ordinary low water : having selected the largest 

 tree, the trunk was sawed oif horizontally, at such a conve- 

 nient height above high water as to serve for the Azimuth 

 circle ; whilst another near it was treated in a similar 

 manner, for the artificial horizon, and the surrounding 

 trees being cleared away, to prevent the vibration arising 

 from the wind on their branches and leaves affecting us, 

 their trunks were lashed horizontally above high-water 

 mark, as rests for the platform, which was composed of 

 heavy planks brought from the ship. The surface of the 

 trunk allotted for the artificial horizon did not, however, 

 afford the space, as well as solidity, required ; three large 

 spike nails were therefore driven in obliquely on its cir- 

 cumference, and on these three points one of our observ- 

 ing slates (twelve inches square, by three inches in thick - 



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