1 Orthography.
432 Etymology.
433 Dictionaries.
434 Synonyms.
435 Grammar.
436 Prosody.
437 Dialects.
438 Texts.
439 Dutch and Low German.

=440 French.=
441 Orthography.
442 Etymology.
443 Dictionaries.
444 Synonyms.
445 Grammar.
446 Prosody.
447 Dialects.
448 Texts.
449 Old French, Provencal.

=450 Italian.=
451 Orthography.
452 Etymology.
453 Dictionaries.
454 Synonyms.
455 Grammar.
456 Prosody.
457 Dialects.
458 Texts.
459 Romansh and Wallachian.

=460 Spanish.=
461 Orthography.
462 Etymology.
463 Dictionaries.
464 Synonyms.
465 Grammar.
466 Prosody.
467 Dialects.
468 Texts.
469 Portuguese.

=470 Latin.=
471 Orthography.
472 Etymology.
473 Dictionaries.
474 Synonyms.
475 Grammar.
476 Prosody.
477 Dialects.
478 Texts.
479 Medieval Latin.

=480 Greek.=
481 Orthography.
482 Etymology.
483 Dictionaries.
484 Synonyms.
485 Grammar.
486 Prosody.
487 Dialects.
488 Texts.
489 Modern Greek.

=490 Other Languages.=
491 Chinese.
492 Egyptian.
493 Semitic.
494 Indian.
495 Iranian.
496 Keltic.
497 Slavic.
498 Scandinavian.
499 Other.

NATURAL SCIENCE.

=500 Natural Science.=
501 Philosophy.
502 Compends.
503 Dictionaries.
504 Essays.
505 Periodicals.
506 Societies.
507 Education.
508 Travels.
509 History.

=5l0 Mathematics.=
511 Arithmetic.
512 Algebra.
513 Geometry.
514 Trigonometry.
515 Conic sections.
516 Analytical geometry.
517 Calculus.
518 Quaternions.
519 Probabilities.

=520 Astronomy.=
521 Theoretical.
522 Practical.
523 Descriptive.
524 Maps.
525 Observations.
526 Figure of the earth.
527 Navigation.
528 Almanacs.
529 Chronology.

=530 Physics.=
531 Mechanics.
532 Hydrostatics.
533 Pneumatics.
534 Acoustics.
535 Optics.
536 Heat.
537 Electricity.
538 Magnetism.
539 Molecular physics.

=540 Chemistry.=
541 Theoretical.
542 Experimental.
543 Analysis.
544 _Qualitative._
545 _Quantitative._
546 Inorganic.
547 Organic.
548 Crystallography.
549 Mineralogy.

=550 Geology.=
551 Physical Geography, Meteorology.
552 Lithology.
553 Dynamical geology.
554 Europe.
555 Asia.
556 Africa.
557 North America.
558 South America.
559 Oceanica.

=560 Paleontology.=
561 Plants.
562 Invertebrates.
563 _Protozoa and Radiates._
564 _Mollusca._
565 _Articulates._
566 Vertebrates.
567 _Fishe