Page:Popular Science Monthly Volume 16.djvu/204

 correspond with the first force in the 4th column, the second sum of hours with the second force, and so on.

As the direction of the wind is given on the charts for only the alternate points, the observations of the intermediate points are distributed among those adjacent. Suppose the transfer of the observations of the sheets of Form B, for one point, to stand on Form D thus: 80 $$+$$ 120 $$+$$ 300 $$+$$ etc. .. . (hours). . . . N. by W. .. . 5; 3; 2; etc. .. . (Force). The point N. by W. not being used, all these observations must be distributed between North and North-northwest—half to each: 1. e., 40 hours, force 5; 60 hours, force 3; and 150 hours, force 2, must all be placed opposite North, and the same opposite N. N. W., just as if they had come from the sheets of Form B. The "Total No. of hours of wind from every alternate point" is now found by adding up the separate periods, and the sum is placed in the 1st column opposite its own point. To obtain the mean force for this sum, each separate period of hours is multiplied by the force peculiar to it, the products are added together, and their sum is divided by the "Total No. of hours of wind from every alternate point"; the quotient is the "Final mean force," which is accordingly placed in the 5th column. The totals of "Calms" and of "Variable winds" are now found, and carried out to the 1st column; then all the figures in this column are added up, and the result is the "Total No. of hours of winds, calms, and variables" observed in square No. 643 during the month of July. To complete the treatment of the winds, the percentage that the total number of hours from every alternate point, as well as the percentage that the calms and the variables are of the total number of hours of observation in the square, are worked out and entered in the 6th column.

On the back of Form D are columns for collecting the other data scattered over the sheets of Form B, viz.: 1. Barometer and thermometers. Beside the mean of each of these quantities transcribed from Form B is placed the number of hours of observation from which that mean is deduced, so that, in obtaining the final mean of the square for the month, due weight can be given to each individual mean. 2. The separate mean daily ranges of the preceding items, with the number of days of which the mean is formed written beside it; 3. The regular daily oscillations of the barometer; 4, The highest and the lowest readings of the barometer and dry-bulb, with the period during which each separate observation was made; 5. The total number of hours of fog, of rain, of squalls (heavy and light), and of gales from each quarter, with their strength; and, 6. A summary of the currents, weather, and magnetic variations. To complete Form D, a résumé of the remarks on the various sheets of Form B is made—a generalization of the experiences of the several ships—and transcribed to the back of the form. When the observations of every square for each month are collected on sheets of Form D in the manner described, the reduction