CONTENTS 



1. -Specifications for Hydrographic Surveys 1 



2. Plans and Preparations 21 



3. Equipment and Instruments 42 



4. Control and Signal Building _. 112 



5. Hydrography 126 



6. The Smooth Sheet _ - 200 



7. Reports and Miscellaneous... — - 241 



Index... 267 



TABLES 



Table Page 



1. Projection line intervals for vai'ious scales 4 



2. Units for recorded soundings and reducers. 14 



3. Standard depth curves 15 



4. Supplemental depth curves _ 15 



5. Scale equivalents for laying out survey sheets 27 



6. Three-letter station names 124 



7. Conversion table — microseconds to meters 131 



8. Conversion table — statute miles to meters.. 132 



9. Distance circle intervals and units 133 



10. Sediments classified by size 160 



11. Example of velocity correction computation.. 183 



12. Conversion of reduced soundings 193 



13. Schedule of penciled and inked details..... 204 



14. Velocity of sound in sea water 256 



15. Salinity corrections (to be applied to Table 14) 256 



16. Pressure corrections (to be applied to Table 14) 258 



17. Velocity correction factors 259 



18. Natural half-cosecants and half-cotangents 264 



19. Linear distance conversion — fathoms — meters — 



feet — yards 265 



20. Linear distance conversion — nautical miles — statute 



miles — kilometers 266 



21. Temperature conversion 266 



ILLUSTRATIONS 



Figure Page 



1. Coast and Geodetic Survey Ship SURVEYOR.. II 



2. Layout of hydrographic sheets 3 



3. Symbols for progress sketches 36 



4. Construction of predicted tide curve 40 



5. Drafting room of a survey ship 42 



6. Hydrographic survey launch _ 43 



7. Hydrographic sextant with endless tangent screw 46 



8. Graph for corrections to inclined sextant angles 49 



9. Three-arm metal protractor . 50 



10. Three-arm plastic protractors 52 



11. Construction of plate for testing protractors.... 53 



80730 



VII 



