168 The Rev. E. Hincks on the Year's and Circles 



He would gladly have reduced the arc of depression, which he must have seen 

 to be too great, by a couple of degrees ; but had he done so, he must, by way of 

 counterpoise, have added as many degrees to the latitude, and thus descended to 

 the extremity of Egypt, which he could not venture to do. But why place 

 " the centre of religion" so low down the Nile as Memphis ? For doing so He 

 has not assigned the shadow of a reason. If we are to seek the cradle of the 

 Egyptian religion, and view the heavens from thence, tradition refers us not to 

 Memphis or Heliopolis, but to Philas, the reputed burial place of Osiris, and the 

 most sacred spot in the country. I will not be so unreasonable, however, as to 

 take M. Biot to the most southern part of Egypt. I propose that we divide the 

 interval, and take Thebes for our observatory. It was the most ancient capital 

 of Egypt, as all are agreed. The latitude of Thebes is 25°. 45', four degrees 

 and a quarter south of M. Biot's parallel, answering to about 600 years, by which 

 I contend that I am entitled to bring down the epoch of coincidence between the 

 solstice and the heliacal rising of Sirius. I have, in fact, calculated the solstice and 

 the Thelan heliacal rising for the year 2550 B. C, using, as M. Biot has done, 

 11° for the arc of depression ; and I find that they took place on the same day, in 

 that and many following years.* 



But in making this calculation I erred by taking so large an arc of depression as 

 11°. M. Biot's reason for taking it is, that it was the value of that arc adopted by 

 Ptolemy. I grant it ; but this seems to me a sufficient reason for rejecting it as 

 excessive. Ptolemy gives it as the arc of depression of the sun below the 

 horizon, which would allow a star to be visible at its rising. He uses it for all 

 stars alike, taking no notice of the inequality in this arc, which their unequal 

 brilliancy and the unequal distance of their places of rising from the part of the 

 horizon over the sun would require. Now, I argue, that, if 11° be the proper 



» In 2550 B. C. I find, using the same data as before, X = 20°. 51'. 40"; ix, = 52". 16'. 0" ; 

 w = 24°. 2'. 8" ; whence we have, for the latitude of 30°, e„ = 80°. 31'. 48" ; 6,, = 94°. 24'. 25" ; 

 but for the latitude of Thebes, (25°. 45') e„ zr 76°. 6'. 12" ; 6,, = 89°. 27'. 52". This year, then, 

 was about the middle one of those in which the solstice coincided with the heliacal rising of Sirius at 

 Thebes ; that is to say, on M. Biot's assumption that the arc of depression should be taken so great 

 as 11°. I cannot but think that 9° or 9°. 30' would be fully sufficient. Now I find that in 2550 

 B. C, at Thebes, Sg = 87°. 1'. 29" ; Sg,, =: 87°. 38'. 2". Subtracting these quantities from 

 89°. 30'. 30", and dividing the remainders by 27", we have in the former case 330 years, and in the 

 'alter case 250 years, as the intervals between 2550 B. C. and the mean epochs of coincidence. 



