occurs arises solely from the high summer temperature. It is to the centre of Asia we must look for an example of this; and accordingly the pressure of the dry air at Barnaul, in Siberia, on a mean of ten years, is 29.760 inches in January, and 28.666 inches in July,-thus showing the enormous difference of nearly eleven tenths of an inch. 687. This question has important bearings on storms, particularly on the storms of Great Britain, which is situated within the southern limits of the region of most anomalous barometric pressure, which has its centre in Iceland. As the summer temperature falls in September and October the pressure is increased over the continents of Asia, Europe, and North America, and consequently air-currents are poured into the northern part of the Atlantic, in larger volume and with accelerated velocity; and since at the same time the temperature is everywhere falling, the whole atmosphere becomes saturated with vapour. This accumulated vapour is discharged in those furious storms of wind and rain which strew our shores with wrecks, and carry misery and desolation into the hearths of our seafaring population. Considering the important interests at stake, no amount of labour and no expense can be regarded as too great which might lead to a better understanding of these great atmospheric disturbances. Z TABLE II.-FOR CONVERTING MILLIMETRES INTO ENGLISH INCHES AND DECIMALS. 661 26.024 687 27.048 713 28.071 739 29.095 765 30.119 662 26.063 688 27.087 714 28.111740 29.134 766 30.158 30.316 29.449 774 30.473 29.489 775 30.512 28.504 750 29.528 776 30.552 28.544 751 29.567 777 30.591 28.583 752 29.607 778 30.630 27.599 727 28.623 753 29.646 779 30.670 27.638 728 29.686 780 30.709 30.749 663 26.103 689 27.126 715 28.150 741 29.174 767 30.197 664 26.142 690 27.166 716 28.189 742 29.213 768 30.237 665 26.182 691 27.205 717 28.229 743 29.252 769 30.276 666 26.221 692 27.245 718 28.268 744 29.292 770 667 26.260 693 27.284 719 28-308 745 29.331 771 30.355 668 26.300 694 27.323 720 28.347 746 29.371 772 30.394 669 26.339 695 27.363 721 28.386 747 29.410 773 30.434 670 26.378 696 27.402 722 28.426 748 671 26.418 697 27.441 723 28.465 749 672 26.457 698 27.481 724 673 26.497 699 27.520 725 674 26.536 700 27.560 726 675 26.575701 676 26.615 702 28.662 754 677 26.654 703 27.678 729 28.701 755 29.725 781 678 26.693 704 27.717 730 28.741 756 29.764 782 30.788 679 26.733 705 27.756 731 28.780 757 29.804 783 30.827 680 26.772 706 27.796 732 28.819 758 29.843 784 30.867 681 26.812 707 27.835733 28.859 759 29.882 785 30.906 682 26.851 708 27.875 734 28.898 760 29.922 786 30.945 683 26.890 709 27.914 735 28.938 761 29.961 787 684 26.930 710 27.953 736 685 26.969 711 27.993 737 29.016 763 30.040 789 31.064 686 27.008 712 28.032 738 29.056 764 30.079 790 31.103 28.977|| 762 30.001 788 30.985 31.024 TENTHS OF A MILLIMETRE IN THE DECIMAL OF AN INCH. 0 1 0.000 8 2 3 4 5 6 7 9 0.004 0.008 0.012 0.016 0.020 0.024 0.028 0.031 0.035 TABLE III.-FOR CONVERTING FRENCH OR PARIS LINES INTO ENGLISH INCHES. A Paris Line equals 0.088814 English Inch. Paris Lines English Paris English. Paris English Paris English Paris English 290.5 25.800 291.0 25. 845 291.5 25.889 27.177 27.221 318.5 288.0 25.578 300.0 26.644 312.0 27.710 324.0 28.776 336.0 29.842 288.5 25.623 300.5 26.689 312.5 27.754 324.5 28.820 336.5 29.886 289.0 25.667 301.0 26.733 313.0 27.799 325.0 28.865 $37.0 29.930 289.5 25.712 301.5 26.777 313.5 27.843 325.5 28.909 290.0 25.756 302.0 26.822 314.0 27.888 326.0 28.953 302.5 26.866 314.5 27.932 326.5 28.998 338.5 303.0 26.911 315.0 27.976 327.0 29.042 339.0 303.5 26.955 315.5 28.021 292.0 25.934 304.0 26.999 316.0 28.065 328.0 29.131 340.0 292.5 25.978 304.5 27.044 316.5 28.110 328.5 29.175 340.5 293.0 26.023 305.0 27.088 317.0 28.154 329.0 29.220 341.0 293.5 26.067 305.5 27.133 317.5 28.198 329.5 29.264 341.5 294.0 26.111 306.0 318.0 28.243 330.0 29.309 342.0 30.374 294.5 26.156 306.5 28.287 330.5 29.353 342.5 30.419 337.5 29.975 338.0 30.019 30.064 30.108 327.5 29.087 339.5 30.152 30.197 30.241 30.286 30.330 28.420 332.0 29.486 344.0 30.552 26.333 308.5 27.399 320.5 28.465 332.5 29.531 344.5 30.596 26.378 309.0 27.444 321.0 28.509 333.0 29.575 345.0 30.641 297.5 26.422 309.5 27.488 321.5 28.554 333.5 29.619 345.5 30.685 298.0 26.467 310.0 27.532 322.0 28.598 334.0 29.664 346.0 30.730 298.5 26.511 310.5 27.577 322.5 28.643 334.5 29.708 346.5 30.774 299.0 26.555 311.0 27.621 323.0 28.687 335.0 29.753 347.0 30.818 299.5 26.600 311.5 27.666 323.5 28.731 335.5 29.797 347.5 30.863 TABLE IV.-FOR REDUCING BAROMETRIC OBSERVATIONS TO THE LEVEL OF THE SEA; AND CONVERSELY, FOR THE DETERMINATION OF HEIGHTS BY THE BAROMETER. .245 .239 .234 210 .256 .250 .229 .224 .219 .215 .211 .008 .240 .235 .230 225 .221 .008 .240 .235 .231 .008 .250 .245 .241 .009 .260 .255 .250 .009 310 .377 .368 .360 .352 .344 .337 .329 320 .389 .380 .372 .363 .348 .340 330 .401 .391 .383 .374 .366 .358 .350 .343 .336 340 .413 .403 .394 .385 .377 .369 .361 .354 .346 350 .425 .415 .406 .897 .388 .380 .371 .364 .356 .349 .013 360 .438 .427 .417 .408 .399 .390 .382 .374 .366 .859 .013 370 .450 .439 .429 .419 .410 .401 380 .462 .451 .440 .430 .421 390 .474 .463 .452 .442 .432 .422 400 .486 .475 .464 .453 .443 .433 410 .498 .487 .475 .464 .454 .444 .434 .425 .417 420 .510 .498 .486 .475 .465 .455 .444 .435 .427 430 .522 .509 .497 .486 .476 .465 .455 .446 .437 440 .534 .521 .509 .497 .487 .476 .465 .456 .447 .437 .016 450 .546 .532 .520 .508 .498 .487 .476 .466 .447 .016 460 .558 .544 .532 .520 .509 .498 .486 .477 .467 .457 .017 470 .570 .556 .543 .531 .520 .508 .497 .487 .477 .467 480 .581 .568 .555 .542 .530 .519 .507 .497 .487 .477 490 .593 .579 .566 .553 .541 500 .605 .591 .577 .564 .551 .322 .316 .310 .011 .333 .326 .320 .012 |