188 Reports & Proceedings — Mineralogical Society. 



the error in calculating average rainfall, due to the preponderance 

 of rain-gauges in the lower ground. 



The determination of water-partings was discussed, and examples 

 quoted where precision is not attainable. 



It was concluded that, although in this country a hydrographic 

 survey, including all the heads of this inquiry, may not be essential 

 on the ground of utility, yet more systematic observations on the work 

 of denudation as now proceeding are within the reach of geologists. 



The ballot for the Officers and Council was taken, and the following were 

 declared duly elected for the ensuing year : — 



Officers: President: Arthur Smith Woodward, LL.D., F.E.S. Vice- 

 Presidents: Henry Howe Bemrose, J. P., Sc.D. ; William Hill; Clement 

 Eeid,F.E.S., F.L.S.; and Aubrey Straban, Sc.D., LL.D., F.E.S. Secretaries: 

 Herbert Henry Thomas, Sc.D., B.Sc, and Herbert Lapworth, D.Sc, 

 M.Inst.C.E. Foreign Secretary: Sir Archibald Geikie, O.M., K.C.B., D.C.L., 

 LL.D., Sc.D. , F.E.S. Treasurer : Bedford McNeill, Assoc. E. S. M. 



The other Members of Council elected were : Professor Thomas George 

 Bonney, Sc.D., LL.D., F.E.S. ; Charles Gilbert Cullis, D.Sc; E. Mountford 

 Deeley, M.Inst.C.E.; James Vincent Elsden, D.Sc; Jobn William Evans, 

 D.Sc, LL.B.; Professor William George Fearnsides, M.A.; Walcot Gibson, 

 D.Sc; Professor Owen Thomas Jones, M.A., D.Sc; Horace W. Monckton, 

 Treas.L.S. ; Edwin Tulley Newton, F.E.S. ; Professor William Johnson SoUas, 

 M.A., Sc.D., LL.D., F.E.S.; William Whitaker, B.A., F.E.S. ; theEev. Henry 

 Hoyte Winwood, M.A. 



II. MiNEEALOGICAL SoCIETY. 



January 27. — Dr. A. E, H. Tutton, F.E.S., President, in the Chair. 

 T. Crook : The Genetic Classification of Eocks and Ore-deposits. 

 The general principles of the classification of rocks were considered, 

 the term rock including all mineral deposits. The exact nature of 

 genetic grouping was defined. Both rocks and ore-deposits fall into 

 broad natural divisions in accordance with a geological grouping 

 of formative agents and processes, the type being determined by the 

 last operative agent or process that gave the rock its individuality. 

 The two main groups are (1) endogenetic deposits, arising from 

 internal causes, and (2) exogenetic deposits, of superficial origin, and 

 these are subdivided in a consistent genetic manner. ' Sedimentary ' 

 and ' metamorphic ' products cannot be regarded as constituting two 

 independent subdivisions. An historical review of the application 

 of genetic-geological principles to the classification of rocks and ore- 

 deposits was included. — Professor A. P. Eogers : Lawsonite from the 

 Central Coast Eanges of California. Crystals from new localities 

 were described ; prismatic and tabular in habit and usually small, 

 they displayed the forms 010, 001, Oil, 110.— A. P. Hallimond : 

 Uniaxial Augite from Mull. The small, lath-shaped crystals, which 

 seldom exceed J mm. in diameter, have refractive indices o 1*714, 

 e 1-744, specific gravity 3"44, pronounced dichroism (o smoky-brown, 

 e pale-yellow), two cleavage directions nearly at right angles, and an 

 extinction angle of 30^° on the cleavage. A chemical analysis revealed 

 distinct differences from ordinary diopside, and the composition 

 approximates to that of hypersthene. — H. H. Thomas and W. Campbell 

 Smith : Apparatus for Grinding Crystal Plates and Prisms. A gun- 

 metal cylinder with its axis normal to a triangular brass-plate, about 



