TRANSACTIONS OF THE SECTIONS. 35 



border of the Mare Humorum. The ring of Fracastorius is so much broken down 

 towards the Mare Nectar is as to give the crater the appearance of a small bay, un- 

 less viewed under a suitable illumination — a very early one — when the edge of the 

 crater towards the Mare is seen as a series of low points or peaks casting very short 

 shadows. The floor of the interior appears to be somewhat different from the sur- 

 face of the Mare, and seems to be slightly depressed below its level. The crater 

 Hippalus is highly interesting; seen under a very early illumination: the western 

 half of the floor is rugged, having a number of hillocks scattered over it and two 

 minute craters ; the eastern half is smooth, very like in appearance to the surfaces of 

 the Maria; but the most remarkable feature is the line separating the crater from 

 the Mare, just as though the Mare had come up to and swept away half the ring of 

 the crater and a portion of its floor, the two extremities of the semicircular range of 

 mountains being very distinct, especially the north-eastern, which terminates ab- 

 ruptly ; not the vestige of a shadow is observed between the two, the light passing 

 between them unobstructedly. 



On the Possibility of Studying the Earth's Internal Structure from Pheno- 

 mena observed at its Surface. By Professor Hennessy, F.R.S. 

 This the author showed to follow as a result from the comparison of the level 

 surface, usually called the earth's surface by astronomers and mathematicians, with 

 the geological surface which would be presented if the earth were stripped of its 

 fluid coating. He had made several comparisons of the arcs of meridian measured 

 in different countries, and had been thus led to the conclusion that the surfaces in 

 question were not only dissimilar, but that the former derived many of the irregular- 

 ities which it is known to present from the influence of the obvious irregularities of 

 the latter. In the absence of precise knowledge of the true figure of the surface of 

 the solidified crust of the earth, as well as of the assumed level surface perpendicular 

 to gravity, theory was necessarily somewhat in advance of observation upon this 

 particular question. At present the number of unknown quantities involved in 

 an inquiry as to the earth's internal structure was greater than the number of condi- 

 tions ; but by knowing the true surface, and adopting the results of established 

 physical and hydrostatical laws relative to the supposed internal fluid mass*, we 

 should be able to form as many equations as we have unknown quantities, and thus 

 ultimately obtain a solution. 



On some Recorded Observations of the Planet Venus in the Seventh Century 

 before Christ. By the Rev. Edward Hincks, D.D., of Killyleagh, 

 Ireland. 



There is a tablet of baked clay in the British Museum, the inscription on which, 

 if I interpret it aright, contains a series of observations of the planet Venus, and a 

 series of predictions grounded on the observations. The latter are of no value ; but 

 the former may in great measure, if not altogether, determine the law by which the 

 AssyrioBahyionian lunar year was regulated in respect to its intercalary months. 

 The knowledge of this law, again, will either establish or disprove the view which I 

 have long entertained, and repeatedly expressed, that the era of Nabonassar was 

 an astronomical, and not a political one ; and I may add, it is not impossible that it 

 may furnish a test of the genuineness of the works attributed to Quthami and other 

 supposed ancient Babylonian writers. For these reasons I am desirous that the 

 observations which I suppose to be recorded should be submitted to astronomers. 

 I now offer two, which will suffice to test the correctness of my interpretation of the 

 records. If any astronomer will take the trouble to calculate whether what is here 

 stated to have happened would have actually happened, and will communicate the 

 result to me, I will, if he desire it, communicate to him other records of observations, 

 as to the interpretation of which I feel less confidence than I do as to these. I observe 

 that the Babylonian months are expressed by monograms, for which I substitute 

 Hebrew names of months. The Babylonian day began at noon ; and that day in 

 the evening of which the new moon was first seen was considered to be the first day 

 of the month. I suppose, but am not very confident, that the year of the first obser- 

 * See Reports for 1859, Trans. Sect. p. 5. 



3* 



