CONTENTS. 
XII. First Memoir on the Theory of Analytical Operations. By the Rev. R. Murphy, 
M.A. Fellow of Cains College, Honorary Member of various Philosophical 
Societies. Communicated by J. W. Lubbock, Esq. F.R.S. . . . page 179 
XIII. On the Adaptation of different Modes of Illuminating Lighthouses ; as depending 
on their Situations and the Object contemplated in their Erection. By W illiam 
Henry Barlow, Esq. In a Letter addressed to Peter Barlow, Esq. F.R.S. 8$c., 
and communicated by Him 211 
XIV. Researches on the Tides. — Eighth Series. On the Progress of the Diurnal In- 
equality Wave along the Coasts of Europe. By the Rev. W. Whewell, M.A. 
F.R.S., Fellow of Trinity College, Cambridge 227 
XV. On the Connexion between the Phenomena of the Absorption of Light, and the 
Colours of thin Plates. By Sir David Brewster, K.H. LL.D. F.R.S. . 245 
XVI. On the Development and Extinction of regular doubly refracting Structures in the 
Crystalline Lenses of Animals after Death. By Sir David Brewster, K.H, 
LL.D. F.R.S. fyc. 8fc. 253 
XVII. On the Temperature of Insects, and its connexion with the Functions of Respi- 
ration and Circulation in this Class of Invertebrated Animals. By George 
Newport, Esq., Member of the Royal College of Surgeons, and of the Entomo- 
logical Society of London. Communicated by P. M. Roget, M.D. Sec. R.S. 259 
XVIII. On the first Changes in the Ova of the Mammifera in consequence of Impregna- 
tion, and on the Mode of Origin of the Chorion. By Thomas Wharton Jones, Esq, 
Communicated by Richard Owen, Esq. F.R.S 339 
XIX. Sequel to an Essay on the Constitution of the Atmosphere, published in the 
Philosophical Transactions for 1826; with some Account of the Sulphurets of 
Lime. By John Dalton, D.C.L. F.R.S. 8$c 347 
XX. On the Hereditary Instinctive Propensities of Animals. By Thomas Andrew 
Knight, Esq. F.R.S., President of the Horticultural Society, Sfc. 8$c. . . 365 
XXI. On the Elementary Structure of the Muscular Fibre of Animal and Organic Life. 
By Frederic C. Skey, Esq. F.R.S., Assistant Surgeon to St. Bartholomew's 
Hospital 371 
XXII. Observations on the Minute Structure of some of the higher forms of Polypi, 
with views of a more Natural Arrangement of the Class. By Arthur Farre, M. B. 
