6 PROGRESS OF SCIENCE. 



The Chaldaeans are justly also credited with the knowledge 

 of these facts, and this is precisely what we should expect 

 considering the antiquity of their civilisation. It is certain 

 that they made original observations and discoveries. They 

 so earnestly pursued the study of astronomy that they had 

 ZIGGURATS (temple-observatories) in almost every important 

 city, and from the time of Sargon I. (3800 B.C.) records of 

 eclipses were kept. They determined the SAROS, a cycle 

 of 223 lunations and an extremely successful attempt to 

 predict eclipses. By calculating the saros at 6,585^ days, 

 and trebling this period, they could predict eclipses to recur 

 in the same part of the heavenly sphere and at the same hour 

 of the day the total error of the three saros being only 

 58 minutes 6 seconds. They thought comets revolved in 

 periodic orbits a wonderful guess. They even knew oi 

 the PHASES OF VENUS ! as we learn from cuneiform tablets 

 nearly 5,000 years old. Callisthenes (330 B.C.) transmitted 

 to Aristotle Chaldsean observations made 2250 B.C. Want 

 of conclusive, or sufficient collateral, evidence outside cunei- 

 form tablets and Berosus, however, leaves us in doubt on 

 the subject of the priority of some of their discoveries. The 

 evidence, on the other hand, in favour of Egyptian priority 

 is so varied and weighty ; the civilisation of the Nile Valley 

 was so complete and homogeneous some 5000 B.C., that, 

 everything considered, Egypt seems on the whole to have 

 been the cradle of science. When we remember that 

 Diogenes Laertius, corroborating, no doubt, Manetho's 

 historical record, mentions that the Egyptians had observed 

 373 solar and 832 lunar eclipses, and that "the ratio between 

 these two numbers exactly represents that which would be 

 the true estimate of eclipses of some 1,200 or 1,300 years/' 

 it is difficult to resist the inference just stated. This view 

 is much strengthened by the position, orientation, measure- 

 ments, and structure of the Great Pyramid, which seem to 

 reveal extraordinary knowledge of geometry, geodesy, and 

 astronomy, since the Egyptians had apparently measured 

 with accuracy an arc of the terrestrial meridian, and inferred 

 that the earth was a sphere of given dimensions.* Chaldaean 

 * See Proctor's work on the subject, not to speak of Piazzi Smith's. 



