CONTENTS Page xi 



Page 



Figure 48. Arrangement for a detachable buoy anchor cable 176 



49. Buoys anchored so as to reduce scope__ 177 



50. East Coast sono-radio buoy structure 180 



51. Vincent sono-radio buoy structure 180 



52. Streamlined buoy for use in strong currents 182 



53. Special hook for use in weighing buoys 188 



54. Systems of sounding lines 196 



55. Maximum sounding-line spacing 201 



56. Corrections to inclined sextant angles when one object is elevated appreciably above 



sea level 222 



57. Distance by depression angle below horizon 229 



58. Probable position of ship from stellar observations 246 



59. Position from star sights, using a known figure of error 246 



60. Handlead sounding from launch 255 



61. Taking sextant angles from an elevated station — 279 



62. Principle of plotting angles without a protractor 287 



63. Layout sheet for graduated perpendicular method 289 



64. Construction of the arcs from rectangular coordinates 291 



65. Drawing the arcs with the use of a protractor 292 



66. Layout sheet for auxiliary straight-line method 292 



67. Principle of auxiliary straight-line method 293 



68. General plan of a survey ship 314 



69. Pilothouse of a survey ship 315 



70. Radio room of a survey ship 3J6 



71. Drafting room of a survey ship 318 



72. Motor vessel E. Lester Jones 321 



73. General plan of a survey launch 324 



74. Handlead sounding from a catamaran 329 



75. The large taut-wire apparatus , 353 



76. Optical principles of a sextant 362 



77. Principal parts of a sextant 363 



78. Metal three-arm protractor with attachments, and celluloid protractor 373 



79. Soiuiding chair extended from top of deckhouse 387 



80. Deep-sea electric sounding machine 389 



81. Hand sounding machine 390 



82. Installation of ship sounding machine 391 



83. Registering sheave — 392 



84. Deep-sea reversing thermotneter 401 



85. Example of thermometer correction graph 402 



86. Oceanographic instruments in position to sound 404 



87. Same oceanographic instruments after sounding 405 



88. Bourdon type bathythermograph 407 



89. Hydrometer set 411 



90. Radio current meter 416 



91. Drafting instruments 419 



92. Metric scale -- 423 



93. Graphic speed scale for field use 427 



94. Graphic speed scale for office use 427 



95. Log-factor scale 428 



96. Triangulation station symbol for Leroy template - 431 



97. Method of sharpening a ruling pen 433 



98. Piezoelectric supersonic acoustic unit 450 



99. Electromagnetic oscillator type 324 '- 456 



100. Launch hydrography using the 808 Fathometer ■- 462 



101. Fish of 808 Fathometer mounted on hydrographic launch J 463 



102. Circuit diagram of 808 Fathometer 467 



103. Support for fish of 808 Fathometer 470 



