CONTENTS. 



ARTICLE PAGE 



I. — A Descent into Elden Hole, Derbyshire. By Rooke Pen- 

 nington, LL.B I 



II. — Certain Lines observed in Snow Crystals. By Arthur W. 



Waters, F.G.S 6 



III.— Notes bearing on Mathematical History. By Sir James 



Cockle, F.R.S., Corresponding Member of the Society... lo 



IV. — On an Instrument for measuring the Direct Heat of the Sun. 



By Professor Balfour Stewart, LL.D. , F.R.S, 1 6 



V. — On a Graphical Method of Drawing Spectra. By Mr. Wil- 

 liam DoDGSON, Whitworth Scholar 20 



VI. — The Eucalyptus near Rome. By Dr. R. Angu.s Smith, 



F.R.S., V.P 25 



VII. — On some Isomerides of Alizarine. By Edward Schunck, 



Ph.D., F.R.S., and Hermann RoEMER, Ph.D 37 



VIII. — On the Manner in which Raindrops and Hailstones are 



formed. By Professor Osborne Reynolds, M. A 48 



IX. — On Changes in the Rates of Mortality from different Diseases 

 during the Twenty Years 1854-73. By Joseph B.iXEN- 

 dell, F.R.A.S 61 



X. — On the Directions of the Face-joints of Oblique Arches. 



By J. B. Millar, B.E 74 



XI. — On a Portrait of Tycho Brahe. By Samuel Crompton, M.D. 77 



XII. — On the Types of Compound Statement involving four 



Classes. By Professor W. K. Clifford, M. A., F.R.S... . 81 



XIII. — On the Law of Force when a Thin, Homogeneous, Spherical 

 Shell e.xerts no Attraction on a Particle within it. By J. 

 H. POYNTING, B.A., B.Sc 96 



