830 THE POPULAR SCIENCE MONTHLY. 



by a throne of massive gold, in which the sun was to come and sit 

 on that day, illuminating the tower on all sides. 



The amantas perceived that only four moons passed when the 

 shadow was turned toward the north, while there were eight 

 moons when it was directed toward the south. They did not take 

 into account that their observatories were situated between the 

 equator and the tropic of Capricorn. But when the Incas had 

 established their residence at Quito, their men of science imme- 

 diately remarked that the two shadows were equal, and that, the 

 duration of their variations was exactly six moons. This is why 

 the columns called equinoctial at Quito were especially venerated 

 as the favorite abode of the great divinity. 



Mr. Wiener mentions another astronomical apparatus which 

 was intended for the precise verification of the time of the equi- 

 noxes : " A vertical well, dug mathematically in the line of the 

 zenith, twice a year, in spring and autumn admitted the rays of 

 the sun and gave light in its lowest depth to a vast tunnel over 

 which it was bored. These observatories were called intihuatanas. 

 These intihuatanas were doubtless real, but the assignment of such 

 a purpose to them was a work of pure imagination/' This appa- 

 ratus, ingenious as it may have been, is too sensibly removed from 

 historical tradition and from the study of the ruins of the solar 

 temples to have really existed. It should further be remarked 

 that such an observatory could be mathematically of service only 

 for the September equinox. 



In tracing the meridian the Incas appear to have limited them- 

 selves to raising a pillar perpendicular to the line which the 

 shadow follows on the day when the sun passes the zenith, and 

 that they reached this result by a series of trials. This accounts 

 for the variations of a few minutes offered in the orientation of 

 some of the monuments. 



The Inca method of determining the solstices was very strik- 

 ing, and nothing like it is found with any other people. On this 

 interesting point we can not do better than literally translate 

 Garcilaso, a descendant of the Incas by his mother, who was better 

 informed upon it than any other writer : " The common people 

 counted the years by the crops, and all were acquainted with the 

 summer and winter solstices. They have left conspicuously 

 visible marks of them. There are eight towers which they con- 

 structed at the east, and eight others which they constructed at 

 the west of the city af Cuzco, arranged in fours, of which two, 

 smaller than the others and about three stories high, were placed 

 between two others much larger. The other two towers were 

 much higher than those which in Spain serve as lighthouses in 

 the seaports and as observatories on the frontiers. These were in- 

 tended for the astrologers, to give them a good view. The spaces 



