INDEX 



567 



N 



Names on chart . . . , . . 381 



Narrow ridge, examination of . . 196 



,, fiords, sketch survey of . . 191 



Natural scale 383 



New navigation . . . . . , 371 



O 



Objects, choice of, for fixing . . 27 

 Observation spots, connection 



with base stations . . . . 70 

 Observation spots, position with 



reference to base stations . . 70 

 Observations, astronomical, when 



to obtain . . 64 

 „ calculating time for 304 

 ,, elimination of er- 

 rors in . . . . 271 

 ,, for error of chrono- 

 meter, set of . . 298 

 ,5 for error of chrono- 

 meter .. ..292 

 ,, for error, form for 306 

 ,, for error, method of 302 

 ,, for latitude .. 271 

 ,, for true bearing . . 351 

 ,, general remarks on 271 

 ,, preparations for . . 275 

 ,, sea for position . . 364 

 ,, on undercurrents 410 

 Observing stars, method of . . 277 

 ,, stool . . . . . . 14 



tides 222 



Obtaining distance between selec- 

 ted positions near the extremes 



of the ship 508 



Ocean bottom, nature of . . 199,405 



Orientation of chart . , . . 95 



Otter sweep . . . . . . 444 



Paper-mounting . . 



,, sizes of 

 ,, stretching of 

 ,, transfer 

 Parallax, adjustment of theodolite 

 for 

 ,, in reading sextant 

 Personal error 

 Photography, reducing plans by 



,, source of error 



Pinnacle rocks 

 Plans, graduation of 

 ,, reducing 

 , , scale in 

 Plotting 



,, by chords 

 ., by distances 



42 



44 



125 



42 



16 

 278 

 307 

 376 

 377 

 197 

 387 

 375 

 382 

 118 

 119 

 126 



PAGES 



Plotting coast-line . ■ • . 185 



,, irregular methods of . . 127 



,, with tracing-paper . . 128 



Plummets . . . . . . . . 82 



Points, necessity of marking . . 374 



,, in transit. . . . . . 28 



Polaris, latitude by . . . . 282 



,, true bearing by . . . . 360 



Pole, ten-foot 40 



use of . . 187, 191 



„ tide 222 



Positions, calculation of, from 

 two angles to three 



known objects . . 170 

 ,, at sea, by Sumner's 



method . . . . 367 



., picking up by sextant 



angles . . . . 197 



Probable error . . . . . . 286 



Projection, gnomonic . . . . 98 



Proofs of rules . . App. A. to F. 



Protractors . . . . . . 34 



R 



