| Angles Degrees | Current Amperes |
| 10 | .088 |
| 20 | .182 |
| 30 | .289 |
| 40 | .420 |
| 45 | .500 |
| 50 | .600 |
| 55 | .715 |
| 60 | .865 |
| 70 | 1.375 |
As the magnetic force that acts upon a magnet needle varies in different places the values given for the current will not be true in all parts of the country. The table gives correct values for the immediate vicinity of Chicago and that part of the United States lying east of Chicago, and north of the Ohio river. The results given should be multiplied by 1.3 for places south of the Ohio river and east of the Mississippi.
Home-Made X-Ray Instrument
Details of X-Ray Machine
Two cylinders, AA, are mounted on a base, B, and mirrors, CC, are fitted at an angle of 45 deg. into these cylinders. Corresponding mirrors, EE, are put in the base parallel with those in those cylinders. An opening extends downward from D of each cylinder so that light entering at one end of the cylinder is reflected down at right angles by the first mirror to the second, from the second to the third, from the third to the fourth which reflects the light to the eye. Thus the light never passes through the cylinders and the observer does not see through, but around any object inserted at X between the cylinders.