CONTENTS. Vv 
NOTICES AND ABSTRACTS 
OF 
MISCELLANEOUS COMMUNICATIONS TO THE SECTIONS. 
MATHEMATICS AND PHYSICS. 
MATHEMATICS. 
: Page 
Address by the Rev. W. WueweE tt, President of the Section ..csscocsesseseeveese = 
Rev. J. Boorn on a General Method of deriving the Properties of umbilical sur- 
faces of the second order, having three unequal axes, from the properties of 
the Sphere ...cecccecocssesccsrscecsecerscceressasstees ecedoeeee wevtpecs savawaeeeh sn ote er 
Rev. J. Boors on the Mutual Relations of Inverse Curves and Inverse Curved 
Surfaces......... Beaunes¥seeesness siete eadeoeaee Pecsieqese seer Peo deeget ave Ribdeuywb ces cow =) eb 
Mr. A. Cavey on the Notion of Distance in Analytical Geometry....s..+ese++0 3 
Mr. J. Pore Hennessy on Dr. Whewell’s Views respecting the Nature and 
Value of Mathematical Definitions .......... sepensbuaneeses Fupdvabte samescceroves'se ieee 
on some Properties of a Series of the Powers of the 
same Number .osscsccsssessccceeersaseececeseeeeceasssscnaseenssceeeseses sees Meee ores 4 
Dr. F. A. SizsestR6M on the Conditions of Equilibrium in a Rotating Spheroid 5 
Mr. G. TuurneEtt on a Mode of constructing the Rectangular Hyperbola by 
POints....c.ccccccccscssesceressseceoes Sndueesesssatecshecttess eechtoeensace potetatedanencetet 5 
Mr. C. M. Wixtrcu on a Mode of constructing Tables of Squares and Cubes. 6 
Lieut, Heart. 
Miss Rosina ZorNuIN on Heat, and on the Indestructibility of Elementary 
Bodies. (Communicated by W. S. AyRTon.)..... Lagperct seovwongavecesseseccerose 6 
Sir Davip Brewster on the Duration of Luminous Impressions on certain 
Points of the Retina........scsccocesssceneereeces De Biaweaaesb de eacddbven os ens ds veece 6 
on Vision through the Foramen Centrale of the Retina. 7 
on certain Abnormal Structures in the Crystalline Lenses 
_of Animals, and in the Human Crystalline ......... orcieert Radenteesaneets Spates 7 
——— on the Crystalline Lens of the Cuttle-fish.........0++. 10 
—-— on the Use of Amethyst Plates in Experiments on the 
Polarization of Light ......... Siete petoccsccaaseaveabeeesececsceons Mevoosueseseveseavce™ IS 
Professor Perzvai’s New Combination Lens............++- sidbici lideteserevetvessevelty 1S 
Mr. Henry Dircxs on an Apparatus for exhibiting Optical Illusions of Spec- 
tral Phenomena ssovassenssvasecesvsenereosbsercescnccsensennconcsvehvessnacsserenseceneeee 1d 
Rev. J. Dinexe on a New Case of Binocular Vision......sssresssseersesseeesreree Ud 
