Vol. XVI. No. 4 THE MAGNETIC DECLINATION AT OSLO OBSERVATORY 1843-1930 9 O'Clock 14 O'Clock D = 18°W + tabulated values in tenths of minutes. D = 18°W + tabulated values in tenths of minutes. (999 = No data) 1842 Jan. Feb. Marz Apr. May June July Aug. Sep. Oct. Nov. Dec. Jan. Feb. Marz Apr. May June July Aug. Sep. Oct. Nov. Dec. 1 999 999 999 999 999 999 343 334 348 379 361 371 999 999 999 999 999 999 457 447 422 414 400 408 2 999 999 999 999 999 999 384 367 357 397 376 368 999 999 999 999 999 999 506 455 432 403 431 385 3 999 999 999 999 999 999 389 352 390 370 378 375 999 999 999 999 999 999 422 420 429 422 440 389 4 999 999 999 999 999 999 362 369 371 361 355 382 999 999 999 999 999 999 397 422 419 433 402 390 5 999 999 999 999 999 999 341 408 368 369 370 390 999 999 999 999 999 999 459 455 434 422 404 382 6 999 999 999 999 999 999 391 418 382 374 363 408 999 999 999 999 999 999 449 452 430 448 401 402 7 999 999 999 999 999 999 335 399 352 357 357 382 999 999 999 999 999 999 440 426 424 450 389 419 8 999 999 999 999 999 999 379 354 362 374 362 372 999 999 999 999 999 999 440 439 428 464 378 399 9 999 999 999 999 999 999 437 358 346 351 376 384 999 999 999 999 999 999 442 439 457 431 397 398 10 999 999 999 999 999 999 362 354 367 359 391 362 999 999 999 999 999 999 429 428 431 412 500 387 11 999 999 999 999 999 999 374 354 367 353 423 367 999 999 999 999 999 999 468 414 465 410 399 378 12 999 999 999 999 999 999 340 343 366 355 362 359 999 999 999 999 999 999 475 457 448 417 392 382 13 999 999 999 999 999 999 333 375 339 358 371 363 999 999 999 999 999 999 446 426 489 460 393 379 14 999 999 999 999 999 999 329 392 346 348 374 382 999 999 999 999 999 999 425 459 427 433 385 389 15 999 999 999 999 999 999 368 350 376 357 371 368 999 999 999 999 999 999 442 427 427 414 368 389 16 999 999 999 999 999 999 359 346 435 380 376 362 999 999 999 999 999 999 454 435 433 403 405 380 17 999 999 999 999 999 999 351 329 443 375 359 370 999 999 999 999 999 999 457 473 426 419 391 377 18 999 999 999 999 999 999 312 400 342 379 363 421 999 999 999 999 999 999 465 451 406 412 385 448 19 999 999 999 999 999 999 390 384 399 341 366 363 999 999 999 999 999 999 450 550 428 434 389 383 20 999 999 999 999 999 999 377 359 354 345 384 369 999 999 999 999 999 999 439 446 446 429 397 378 21 999 999 999 999 999 999 346 371 364 323 401 367 999 999 999 999 999 999 456 445 455 414 404 383 22 999 999 999 999 999 999 339 349 365 342 407 373 999 999 999 999 999 999 477 459 448 414 385 386 23 999 999 999 999 999 999 440 356 365 365 381 372 999 999 999 999 999 999 454 452 401 415 412 386 24 999 999 999 999 999 999 321 343 366 344 370 366 999 999 999 999 999 999 437 504 423 434 389 374 25 999 999 999 999 999 999 341 351 343 356 372 368 999 999 999 999 999 999 449 436 422 397 399 405 26 999 999 999 999 999 999 352 335 331 356 376 364 999 999 999 999 999 999 464 443 424 398 400 381 27 999 999 999 999 999 999 362 364 359 384 362 367 999 999 999 999 999 999 493 429 443 466 379 390 28 999 999 999 999 999 999 344 398 353 382 369 362 999 999 999 999 999 999 464 426 414 398 384 380 29 999 999 999 999 999 341 327 367 358 388 354 999 999 999 999 999 489 436 418 398 430 374 30 999 999 999 999 999 370 344 379 385 364 367 999 999 999 999 999 472 435 415 404 414 426 31 999 999 999 385 356 356 374 999 999 999 453 434 389 391 Mean 999 999 999 999 999 999 361 363 367 362 374 373 999 999 999 999 999 999 454 446 432 421 401 391