670 KANSAS CITY REVIEW OF SCIENCE. 
distorted human countenance, and about it were geometrical signs, and figures 
of animals, reptiles, birds, and specimens of vegetation. 
There were characters the interpretation of which presented a history of the 
creation of the earth. There was a period when there was no sun and the tigers 
came out of the woods and devoured everything. After a time the sun -'died 
again," and there were great hurricanes of wind, causing them to perish. An- 
other age was that of the flood, when everything was submerged, and the last 
epoch was that of fire, and men became birds. Around and about these central 
figures were cycles containing representations of the days of the month, the days 
of the year and other peculiarities. 
Some antiquarians thought that it was a calendar stone, but Mr. Molera had 
an idea that it was designed for one of the sacrificial stones on which captives 
were slain, their hearts being offered to the sun. He believed it was constructed 
under the second Montezuma, who, having done nothing to perpetuate his name, 
determined to construct a sacrificial stone, the same as his predecessors had done. 
He wanted to make it larger than any of the others, and gave orders that it be 
two elbows larger than they were. 
The Indians began hauling the stone, which finally said it would not go any 
further. There were 10,000 Indians pulling the stone, and the ropes broke and 
the stone would not move. This the historians cite to show that supernatural 
phenomena were connected with the event. However, it appears that the stone 
was really brought to town, and it was so heavy that it broke the canal and fell 
down. 
GEOLOGY. 
A GEOLOGICAL LESSON. 
PROF. S. H. TROWBRIDGE, GLASGOW, MO. 
As a simple illustration of the way in which nature should be taught, and of 
the ease with which young persons can be interested in nature studies, I will 
give a true and consecutive account of an hour's ramble of Mr. Inquisitive and 
his three little boys, aged nine, seven, and five years, and, for convenience, 
named by the numbers indicating their respective ages. 
After leaving the street on which they live, and perhaps three minutes from 
home, they come to the top of a hill from which could be seen several other 
hills with valleys or ravines between them. Here the father gave the boys the 
first scientific problem to solve for themselves, in this form : " How came the 
valleys between all these hills ?" The first solution, given almost immediately 
