670 



HRYDOGRAPHICAL SURVEYING 



Triaagulatioii by means of floating 

 moored beacons 

 „ calculated 



„ ,, example 



of .. 

 ,, calculating 



,j co-ordination of re- 



sults with astro- 

 nomical positions 

 ,, correcting for error 



of base . . 

 ,, definition of 



,, errors in . . 



,, general 



,, kinds of . . 



,, main 



., preparation 



calculation of 

 ,, by sextant 



Tripods 



Trough, amalgamated 

 True bearing 



„ ,, by equal altitudes 

 „ „ by polaris . 

 ,, ,, by sextant. . 

 ,, ,, by single altitude . . 

 ,, „ calculation of, be- 

 tween two astro- 

 nomical positions 

 ,, „ elimination of errors 



in 

 ,, ,, for orientation 



for 



472 



79 



103 

 102 



11 



108 

 78 



110 

 62 



78 

 78 



95 



83 



48 



15 



351 



352 



213, 360 



356 



355 



108 



108 

 95 

 ,, ,, use of, in plotting 128, 131 



U 



Undercurrents, observations of . . 416 

 „ rough estimation of 410 



PAGES 



Vacuum tide gauge . . . . 453 



Valuing results of observations . . 286 



Variation . . . . . . • . 361 



,, by sea observations .. 361 



, , by shore observations . . 362 



Venus, use of, by day . . . . 366 



Vernier, setting . . . . . . 303 



Views . . . . . . . . 95 



Vigias, searching for . . . . 214 



,, procedure at night when 



searching for . . . . 217 



,, spacing of soundings . . 216 



,, submarine sentry valuable 216 



,, use of contour lines . . 216 



Voyages, sounding on . . . . 403 



W 



Watches, comparing 

 Water level, mean 



,, line, low . . 

 Weights 

 Weir's diagram 

 Whalers 

 Whitewashing 

 Wire, condemnation of 



,, splices in . . 



,, splicing to hemp 



,, strength of . . 



,, weight of . . 



,, winding 



Zero, choice of 



,, lines, selection of 



,, verifying 

 Zeros, selection of 



231, 233, 



299 

 249 

 190 



42 

 372 



51 

 • 48 

 393 

 394 

 396 

 394 

 397 

 396 



84 

 122 



86 

 168 



BILLING AND iONS, LTD., PRINTERS, GUIHiFORD, ENGLAND. 



