CONTENTS Page vii 



Page 



42. Survey launches and small boats 322 



421. General description of survey launches. 422. Launch eauipment. 



423. Leased launches. 424. Small boats. 



43. Equipment and instruments 330 



431. Care of equipment and instruments. 432. Instrument requisitions. 433. Ac- 

 countability for instruments. 434. Shipments of instruments. 



44. Navigation and position-location equipment 335 



441. Magnetic compass. 442. Gyrocompass. 443. Compass auxiliaries. 

 444. Radio direction finder. 445. Ship logs. 446. Taut-wire apparatus. 



45. Navigation and position-location instruments 361 



451. Sextant. 452. Sextant angles. 453. Protractors. 454. Timepieces. 

 455. Rangefinder. 



46. Depth finding equipment and instruments 383 



461. Sounding pole. 462. Leadline. 463. Sounding machines. 464. Registering 

 sheaves. 465. Sounding wire. 466. Sounding leads and weights. 467. Tide 

 gages. 



47. Oceanographic instruments 400 



471. Deep-sea thermometers. 472. Reversing thermometer frames. 473. Bathy- 

 thermograph. 474. Water specimen cups. 475. Hydrometer sets. 476. Bottom 

 sample devices. 477. Roberts radio current meter. 478. Other oceanographic 

 instruments. 



48. Drafting instruments 418 



481. Dividers. 482. Scales. 483. Miscellaneous drafting instruments. 484. Pens. 

 485. Other drafting instruments. 486. Requisitions for drafting materials. 



Chapter 5.— ECHO SOUNDING 



51. General statement 437 



511. Principles of echo sounding. 512. History of echo sounding. 513. History 

 of echo sounding in the Coast and Geodetic Survey. 514. General limitations of echo 

 sounding. 515. General classification of echo-sounding instruments. 516. Descrip- 

 tion and function of parts. 



52. Echo-sounding instruments used by the Coast and Geodetic Survey 455 



521. 312 Fathometer. 522. Simplex-Bludworth. 523. 808 Fathometer. 524. Dorsey 

 Fathometer No. 1. 525. Dorsey Fathometer No. 2. 526. Dorsey Fathometer No. 3. 

 527. Veslekari. 528. Hughes MS 12 D. 529. Bludworth depthometer. 



53. Foreign echo-sounding instruments 499 



531. French instruments. 532. English instruments. 533. German instruments. 



54. Echo-sounding instrument installation 503 



541. Dorsey No. 1 installation. 542. Dorsey Nos. 2 and 3 installation. 

 543. Veslekari installation. 544. Semiportable installation. 545. The advantages 

 of two echo-sounding instruments. 



55. Adjustment and verification of echo-sounding instruments 507 



551. Draft. 552. Instrumental error. 553. Settlement and squat. 554. Adjust- 

 ment of index. 555» Motor speed. 556. Separation effect. 557. Bar check. 



56. Corrections to echo soundings 527 



561. Velocity corrections. 562. Mechanical corrections to fathogram soundings. 

 563. Errors caused by bottom slope. 



57. Echo-sounding instrument operation 542 



571. Fathogram interpretation. 572. Instrument tests and maintenance. 



58. Echo-sounding expedients 552 



581. Deep-water sounding with the 312 Fathometer. 582. Sounding with bombs. 



Chapter 6.— RADIO ACOUSTIC RANGING 



61. General statement 555 



611. History of development. 612. Theory of R.A.R. 613. Practical use of 

 R.A.R. 



