436 I1TOE2. 



rage, 



ttaBciary Distarbanct.-s, Prof. Snell's Lecture on - --- 375 



La-ws of Force and Motioa 175 



Ineitia and Gravitatioa J75 



Illustrations of Astronomical Movements 176 



Experiments with the Eotascope 177 



Precession i£ the Equiaoses 179, 183 



Eetrogradation of the Moon's Nodes - --- 179,185 



Law of Composition of Eotary Motions — — 180 



Advance of Apsides 1°^ 



Plants added io the Musenm ^^ 



Plants, Obseivations to be made on 259 



List of -— - - 260 



Pole Star, Gradual change of ^^^ 



Pope, Capt., Explorations by '** 



Potts, Juo., C^ollectioas from ^ 



Power, Keal sovirce of, explained l"*^ 



Plrecession of the Equinoxes, Explanation and iilastration of 183 



Premiiims for Collections in Natuiral History &5 



Prescott, Wm. H., Letter from.. — - - 309 



Programme of Organization of the Institution ^^ » 



PsychroBieter, Directions for use of 220 



Publications during 1855 17,36 



Pybas, B., Exchange of shells desired bj ^7 



Quincy, Hon. Josiah, HonatJon to Harvard 22 



Eain, Dircctioiis for observation of 236 



Observations on quantity of, at different heights 211 



Eain Gage, Description and directions for use of 227 



New forms adopted ■ 2t, 2-9,230 



Becent Progress in Physk-s, P.eport on Galvanism 311 



Eeductions of Meteorological Observations 27 



Eegents of the Institi-ition, List of 5 



Eegents, Appointment and election of 76 



Begistry of Periodical Phenomena 259 



Eelative Li tensity of the Light and Heat of the Sun ..- 20 



Eeport of recent progress in Physics — 311 



Eeport of the Building Committee - 73 



Eeport of the Executive Committee 6* 



Eeport of the Secretary for 1855 — - - 13 



Eeport of the Senate Judiciary Committee 83 



Eeptiles, Observations to be made on 262 



Specimens added to Museum "^7 



Eesearch, special lines encouraged 20 



Eesearches made in the Institution during 1855 26 



Eesolutions of Board respecting Appropriations and Division of the Income 12 



Eesolutions of Illinois Board of Education on Meteorology 81 



Eesolution of the House of Representatives relative to printing extra copies of 



report , 



Eetrogradation of the Moon's Nodes explained - 185 



