IV 
Contents. 
PAGE 
The Absorption Spectra of Certain Vegetable Colouring Matters. 
By Prof. C. Michie Smith. (With a Plate), . . .121 
On a Mechanism for the Constitution of Ether. By Sir William 
Thomson, ........ 127 
On the Swimming Bladder and Flying Powers of Dactylopterus 
volitans. By W. L. Calderwood. Communicated by Professor 
Ewart. (With a Plate), / . . . . .132 
Notes on the Solution of certain Equations. By R. E. Allardice, 
M.A., ........ 139 
Notes on the Zodiacal Light. By Prof. C. Michie Smith, . .142 
On the Structure and Contraction of Striped Muscular Fibre of the 
Crab and Lobster. By Professor William Rutherford, M.D., 
F.R.S., . . . . . . . .146 
Some Multinomial Theorems in Quaternions. By the Rev. M. M. 
U. Wilkinson. Communicated by Professor Tait, . . .149 
On an Accidental Illustration of the Effective Ohmic Resistance to 
a Transient Electric Current through a Steel Bar. By Sir 
William Thomson, ....... 157 
On the Segmentation of the Nucleus of the Third Cranial Nerve. 
By Dr Alex. Bruce. (With Two Plates), . . . .168 
On the Nature of a Voluntary Muscular Movement. By John 
Berry Haycraft, M.D., D.Sc., ..... 176 
Muscular Contraction following Rapid Electrical Stimulation of 
Central Nervous System. By John Berry Haycraft, M.D., D.Sc., 178 
Synthesis of Sebacic Acid. By Prof. Crum Brown and Dr James 
Walker, ........ 180 
On the Relation of Optical Activity to the Character of the Radicals 
united to the Asymmetric Carbon Atom. By Prof. Crum Brown, . 181 
On the Mean Level of the Surface of the Solid Earth. By Hugh 
Robert Mill, D.Sc., . . . . . . 185 
A Geometrical Method, dependent on the Principle of Translation. 
By David Maver. (With a Plate), . . . . .188 
Graphic Records of Impact. By Professor Tait, . . .192 
On the Number of Dust Particles in the Atmosphere of certain 
Places in Great Britain and on the Continent, with Remarks on 
the Relation between the Amount of Dust and Meteorological 
Phenomena. By John Aitken, F.R.S. (With Three Plates), . 193 
Larix Europcea as a Breeding-Place for Hylesinus piniperda. By 
William Somerville, D.CEc., B.Sc., .... 255 
Researches on Micro-Organisms, &c. Part III. By Dr A. B. 
Griffiths, F.R.S. (Edin.), F.C.S. (Lond. & Paris), Member of the 
Physico-Chemical Society of St Petersburg, &c., . . . 257 
On the Solution of the Three-Term Numerical Equation of the nth. 
Degree. By the Hon. Lord M‘Laren, .... 270 
