24S TRAVELS ON THE RIO NEGRO. [March, 



though it had been seen in its cage on the preceding day. I 

 thus lost perhaps my only chance of obtaining a much-desired 

 and probably undescribed river turtle, as the time of egg-laying 

 was past, and they had now retired into the lakes, and become 

 very scarce and difficult to be met with. 



As my Indians were here doing nothing, I sent three of 

 them with Sebastiao up the Codiarf, with beads, hooks, mirrors, 

 etc., to buy monkeys, parrots, or whatever else they could 

 meet with, as well as some farinha, which I did not wish to be 

 in want of again. I sent them with instructions to go for five 

 or six days, in order to reach the last stitio, and purchase all 

 that was to be had. In two days, however, they returned, 

 having been no further than Philippe had gone, Sebastiao 

 saying that his companions would not go on. He brought me 

 some parrots and small birds, bows, bird-skins, and more 

 farinha than my canoe would carry, all purchased very dearly, 

 judging by the remnant of articles brought back. 



Being now in a part of the country that no European 

 traveller had ever before visited, I exceedingly regretted my 

 want of instruments to determine the latitude, longitude, and 

 height above the sea. The two last I had no means whatever 

 of ascertaining, having broken my boiling-point thermometer, 

 and lost my smaller one, without having been able to replace 

 either. I once thought of sealing up a flask of air, by accurately 

 weighing which on my return, the density of air at that 

 particular time would be obtained, and the height at which a 

 barometer would have stood might be deduced. But, besides 

 that this would only give a result equal to that of a single 

 barometer observation, there were insuperable difficulties in 

 the way of sealing up the bottle, for whether sealing-wax or 

 pitch were used, or even should the bottle be hermetically 

 sealed, heat must be applied, and at the moment of application 

 would, of course, rarefy the air within the bottle, and so produce 

 in such a delicate operation very erroneous results. My 

 observations, however, on the heights of the falls we passed, 

 would give their sum as about two hundred and fifty feet ; now 

 if we add fifty for the fall of the river between them, we shall 

 obtain three hundred feet, as the probable height of the point 

 I reached above the mouth of the river ; and, as I have every 

 reason to believe that that is not five hundred feet above the 

 sea, we shall obtain eight hundred feet as the probable limit oif 



