566 



HYDROGRAPHICAL SURVEYING 



distance of true . . App. Q. 

 ,, visible Apps. E., P. 

 stand . . . . . . 14 



Inequality, diurnal . . . . 221 



,, semi-menstrual . . 221 



Inferior transit, equal altitudes 

 at . . . . . . 296, 310 



Interpolation, meridian distance 



by .. .. 341 



,, meridian distance 



with harbour rates 348 

 Intervals of time in decimals of a 



day App. S. 



Irregular methods of plotting . . 127 

 ,, plotting, examples of . . 131 



Latitude (at sea) by circum-mer- 

 idian altitudes of sun 372 

 ,> by circum-meridian alti- 

 tudes of stars . . 272 

 ,, by circum-meridian alti- 

 tudes of sun . . . . 289 



,, by pole star . . . . 282 



,, by stars, example . . 283 



,, by stars, valuing . . 286 



,, observations for . . 271 



Leading marks . . . . . . 205 



Lead-lines . . . . . . . . 54 



,, marking .. .. 55 



,, measuring .. .. 207 



Leadsmen's chains . . . . 51 



Levelling 268 



Level , mean water 23 1 , 233, 249 

 Levels on sextant stand, advan- 

 tages of . , . . . . . . 278 



Lighthouses . . . . . . 50 



L'g'itvessels and their moorings 



and their use in triangulation 503 



I'AOKS 



Line, straight ruling . . , 122 



Local attraction . . . . . . 290 



Log, current . . . . . . 244 



Logs, patent . . . . . . 53 



Longitude, absolute . . . . 292 



,, at sea, double altitude 367 

 ,, by short equal alti- 

 tude . . . . 372 



differential .. ..292 



Lunitidal interval . . . . 221 



M 



Miin angle book, entering calcu- 

 lated angles in 125 

 ,, ,, entering sextant 



angles . . 83 



Main station, making . . . . 84 



,, stations . . . . . . 78 



,, triangulation . . . . 78 



Mark boats . . . . . . 49 



Marks 47 



,, alphabetical namhig of . . 165 



,, fixing . . . . . . 165 



,. in transit for directing 



lines . . . . . . 196 



,, selection of positions for 166 



, , tripods . . . . . . 48 



,, use of canvas . . . . 49 



,, whitewashing . . . . 48 



Masthead, measurement of height 50 

 Mean- water level . . 231, 233, 249 



Measured base not necessary . . 81 

 Measures, foreign, of depth App. V. 



Measuring chains . . . . . . 34 



,, lead-lines . . . . 20 



Merca tor's projection, transferring 



to 

 Meridian distance 



390 

 293, 326 

 by harbour 



rates 344, 346 



by interpola- 

 tion . . 

 by interpola- 

 tion by har- 

 bour rates . . 

 by rockets 

 by travelling 



rates 

 chronometric 



294, 333 

 . . 350 

 .. 326 

 . . 279 



341 



348 

 349 



333 



,, ,, return of 



,, ,, telegraphic 



Meridian, reduction to . . 



,, secondary . . . . 293 



Meridians, convergency of . . 97 



Mirrors, resilvering . . . . 11 



Moon's transit 221 



Mounting field boards . . . . 45 



,, paper . . . . . . 42 



Mud flats, effect of . . . . 236 



