ON INTRODUCED ANIMALS AND PLANTS. 157 



calendar years, and of precisely 562,465 days. As, however, the 

 Egyptian Enumeration of the days appears to have gone on without 

 interruption, it seems probable, that the Great Year really consisted of 

 1540 calendar years, or of 562,100 days: now the nearest of the above 

 approximations, 



365 d 5 h 48 m 49-7 s (the Solar year) — 8 m 17-6', or more exactly, 

 365| d — 19 m 27||^ s X 1539 = 562,098 <1 22 h 41 m 38f™ s , 



gives a difference of more than an entire day. 



It was only after my book had been printed and published, that I 

 obtained a number which satisfies all the requirements : 



1 day — H = 1389 5 y = 1389 7 y j and 

 1389 JL 1440 1440 



II . . . . . 1 Q 5 17 in , nr 1 C|m OQ 2 fi 9 9 \ 



77 77 • • 77 ly T337 ( 0r lJ Zd T337 )■ 



From the Solar or Natural year = 365 d 5 h 48 m 49-7% 

 deduct 365| d — 19 m 23 T 2 &y =365 5 40 36}g«s . 

 and the remainder, 8 12 -9, 



differs only a fraction of a second from Roemer's quantity ; a fraction 

 too small to be easily reached by instrumental observation. Granting, 

 however, that it can be reached and rendered sensible; as astronomers 

 use sidereal time, and as everything relating to the Egyptian Great 

 Year is in solar time, the difference between solar and sidereal time 

 proves to be in favour of the new quantity. In regard to the third 

 test, the difference in the length of the Great Year amounting to less 

 than an entire day, might readily escape the notice of the Egyptian 

 community ; 



365 d 5 h 40 m 36-|0|8s x 1539 = 562,099 d h 43f|f4 m . 



Up to this stage in the investigation, I had not doubted the correct- 

 ness of the received Theory of the progressive motion of light. I had 

 been in search of a smaller quantity than 8 m 12'9 S ; for the Sun itself 

 occupying no inconsiderable portion of the diameter of the Earth's orbit, 

 g m 12-9 3 d n ot correspond to the alleged rate of travel from the Sun's 

 surface to our Earth; whether at the Equinoctial points, or even at 

 the average orbital distance. This led to an examination into the 

 origin of the Theory : 



