'The interaction of three or more lines is studied, but only those that meet with absolute precision. A moment's reflection shows that even using the most precise measurements, such coincidences could function only within an error of the thickness of one line, whereas this apparently uncontrolled operation has resulted in greater precision.---/The probability of these three different effects is far greater with b. and c. than with a. Now from the mathematics of chance one such effect can be the result of hazard, two of coincidence, three would constitute a strong coincidence; and four or more suggest a cause beyond the laws of chance. The purpose of this experiment is to permit the beginner to achieve confidence in his own action, for which purpose the experiment may be effective. This confidence is not verbal; it can be verified only in the action of the person.'
Fig.160. figure 158 with
emphasized intersection points
An implausible even highly improbable number of exact coincidence of three or more lines is emphasized at their intersections.