1820.] Proceedings of Philosophical Societies. 447 



2. In the American opossum, the yelk bugs are formed in the 

 ovaria, pass into the uteri, there receive the albumen, and are 

 then impregnated. The foetus in each uterus is aerated by one 

 lateral tube. When expelled from these uteri, the young are 

 received into the marsupiura, and become attached to the nipples 

 of the mother. 



3. In the ornithorhynchi, the yelk bags are formed in the 

 ovaria, received into the oviducts in which they acquire the 

 -albumen, and are impregnated afterwards. The foetus is aerated 

 by the vagina, and hatched in the oviduct, after which the young 

 provides for herself, the mother not giving suck. 



VI. The Results of Observations made at the Observatory of 

 Dublin for determining the Obliquity of the Ecliptic, and the 

 Maiimuni of the Aberration oj' Light. By the Rev. J. Brinkley, 

 D.J). F.R.Si. and M.R.I.A. and Andrew's Professor of Astro- 

 nomy in the University of Dublin. — The mean obliquity of the 

 ecliptic on Jan. 1, 181^5, deduced from the summer solstices, 

 Tvas found to be 23° 21' 50*4o". The mean obliquity of the 

 ecliptic on Jan. 1, 1755, as deduced by Bessel from Bradley's 

 observations, was 23° 28' 15-49". This gives 0-43" for the 

 annual diminution. 



The maximum aberration of light, deduced by Dr. Brintley 

 from 166 observations, is 20'8U'''. Bessel, from Bradley's 

 observations, has determined it at 20'70''' nearly. These are so 

 much greater than was expected, that Dr. Brinkley thinks they 

 ■will not be admitted by astronomers till verified by others. He 

 solicits the attention of astronomers to this subject, which he 

 considers as of great importance. 



{Tu be continued.) 



Article IX. 



Proceedings of Philosophical Societies. 



ROYAL SOCIETY. 



April 20. — A paper, by W. Kitchener, M.D. was read, enti- 

 tled, " On an Improvement in the Eye Tubes of portable Achro- 

 matic Telescopes." It has been long known that by increasing 

 the distance between the two glasses next the eye and the two 

 next the object, the magnifying power of telescopes may be 

 nearly doubled. After several attempts to improve this principle, 

 the author stated that he has at length succeeded, and rendered 

 it so complete, that vision throughout a great range of power is 

 perfect oven to the edges of the field. Applied to an object glass 

 of 30 inches focus and 2-7 inches aperture, he stated that his 

 improved eye tube produces in the most perfect manner any 

 intermediate power between 70 and 270, and with an achroma- 



