The Divining Perspective Glass
Procure a small perspective-glass, wide enough, where the object-glass
is placed, to hold the following table:
+-------+--------+--------+
1,131 10,132 19,133
2,231 11,232 20,233
3,331 12,332 21,333
+-------+--------+--------+
4,121 13,122 22,123
5,221 14,222 23,223
6,321 15,322 24,323
+-------+----
---+--------+
7,111 16,112 25,113
8,211 17,212 26,213
9,311 18,312 27,313
+-------+--------+--------+
Take a pack of twenty-seven cards; give them to a person, bid him fix,
on one, shuffle them, and return them to you. Arrange the twenty-seven
cards in three parcels, by laying one down, alternately, on each
parcel; but before you lay each card down, show it to the person,
without seeing it yourself. When you have completed the three parcels,
ask him at what number, from one to twenty-seven, he will have his
card appear, and in which heap it then is. You then look at the heap
through your glass; and if the first of the three numbers, which
stands against the number it is to appear at, be one, put that heap at
top; if the number be at two, put it in the middle; and if it be
three, put it at the bottom. Next divide the cards into three heaps,
in the same manner, a second and third time, and his card will be at
the number he chose.