0.10 169 225 240 0.16 210 285 305 0.20 240 320 340 0.25 270 355 380 0.40 340 450 480 0.60 420 550 590 0.80 480 630 680 1.20 585 775 840 1.80 720 950 1020 3.00 930 1220 1320 5.00 1200 1600 1700 8.00 1500 2000 2150 12.00 1850 2400 2650 16.00 2150 2800 3050 From Table I you can find how much inductance you will need in the primary circuit. A certain amount you will need to couple the antenna and the secondary circuit. The coil which you wound at the beginning of your experiments will do well for that. Anything more in the way of inductance, which the antenna circuit requires to give a desired wave-length, you may consider as loading. In Table II are some data as to winding coils on straight cores to obtain various values of inductance. Your 26 s. s. c. wire will wind about 54 turns to the inch. I have assumed that you will have this number of turns per inch on your coils and calculated the inductance which you should get for various numbers of total turns. The first part of the table is for a core of 3.5 inches in diameter and the second part for one of 5 inches. The first column gives the inductance in mil-henries. The second gives number of turns. The third and fourth are merely for convenience and give the approximate length in inches of the coil and the approximate total length of wire which is required to wind it. I have allowed for bringing out taps. In other words 550 feet of the wire will wind a coil of 10.2 inches with an inductance of 8.00 mil-henries, and permit you to bring out taps at all the lower values of inductance which are given in the table. Table II Part 1. (For a core of 3.5 in. diam.)