APPENDIX B 367 



compass is preferred, nothing smaller than two and one half inches 

 in diameter should be used. In the smaller sizes the magnet is not 

 powerful enough to move the dial quickly or accurately. 



Several good pocket compasses must be provided. They should all 

 have good-sized needles with the north end well marked and degrees 

 engraved in metal. If the floating dial is preferred it should be of 

 aluminum and nothing smaller than two and one-half inches, for the 

 same reason as mentioned above regarding the prismatic compass. 



Expense should not be spared if it is necessary to secure good 

 compasses. Avoid paper dials and leather cases which absorb mois- 

 ture. The compass case should allow taking apart for cleaning and 

 drying. 



The regular chronometer movement, because of its delicacy, is out 

 of the question for rough land or water travel. We had with us a small- 

 sized half-chronometer movement recently brought out by the Wal- 

 tham Company as a yacht chronometer. It gave a surprisingly even 

 rate under the most adverse conditions. I was sorry to lose it in the 

 rapids of the Papagaio when our canoes went down. 



The watches should be waterproof with strong cases, and several 

 should be taken. It would be well to have a dozen cheap but good 

 watches and the same number of compasses for use around camp and 

 for gifts or trade along the line of travel. Money is of no value after 

 one leaves the settlements. I was surprised to find that many of the 

 rubber hunters were not provided with compasses, and I listened to an 

 American who told of having been lost in the depths of the great forest 

 where for days he lived on monkey meat secured with his rifle until 

 he found his way to the river. He had no compass and could not 

 get one. I was sorry I had none to give; I had lost mine in the 

 rapids. 



For the determination of latitude and longitude there is nothing 

 better than a small four or five inch theodolite not over fifteen pounds 

 in weight. It should have a good prism eyepiece with an angle tube 

 attached so it would not be necessary to break one's neck in reading 

 high altitudes. For days we travelled in the direction the sun was 

 going, with altitudes varying from 88° to 90°. Because of these high 

 altitudes of the sun the sextant with artificial horizon could not be 

 used unless one depended upon star observations altogether, an un- 

 certain dependence because of the many cloudy nights. 



