CONTENTS 
OF VOL. 159. 
I. Researches on Solar Physics. Heliographical Positions and Areas of Sun-spots 
observed with the Kew Photoheliograph during the years 1862 and 1863. By 
Warren De La Rue, Psg., Ph.D., F.R.S., F.R.A.S. , Pres. C.S., Balfour Stewart, 
Fsg., LL.B ., F.R.S., F.RA.S., Superintendent of the Kew Observatory , and 
Benjamin Loewy, Fsg., F.R.A.S page 1 
II. A Third Memoir on Skew Surfaces, otherwise Scrolls. By Professor Cayley, 
F.R.S Ill 
III. Description of the Great Melbourne Telescope. By T. R. Robinson, D.D., F.R.S. , 
Ac., and Thomas Grubb, Fsg., F.R.S., Ac 127 
IV. The Formation and Early Growth of the Bones of the Human Face. By George 
W. Callender, Lecturer on Anatomy at St. Bartholomew's Hospital. Commu- 
nicated by J. Paget, F.R.S 163 
V. On Hydrofluoric Acid. By G. Gore, F.R.S 173 
VI. A Memoir on the Theory of Reciprocal Surfaces. By Professor Cayley, 
F.R.S. 201 
VII. A Memoir on Cubic Surfaces. By Professor Cayley, F.R S 231 
VIII. On the Osteology of the Solitaire, or Didine Bird of the Island of Rodriguez , 
Pezophaps solitaria ( Gmel .). By Alfred Newton, M.A., Professor of Zoology 
and Comparative Anatomy in the University of Cambridge, and Edward Newton, 
M.A., Auditor- General of Mauritius. Communicated by P. L. Sclater, M.A., 
Ph.D, F.R.S 327 
IX. On the Solar Variations of Magnetic Declination at Bombay. By Charles 
Chambers, Fsg., Superintendent of the Colaba Observatory. Communicated by 
Balfour Stewart, F.R.S. 363 
X. Observations on the Development of the Semilunar Valves of the Aorta and Pulmo- 
nary Artery of the Heart of the Chick. By Morris Tonge, M.A., M.D. Com- 
municated by Dr. Beale, F.R.S. 387 
