19 



undulations above, and two below the equator. The right section 

 of this cone presents two opposite hyperbolas between asymptotes 

 which cross one another at right angles This cone varies in its 

 breadth in different positions of the sphere ; diminishing as the la- 

 titude of the place increases. 



The cones to which the other ancient hour lines belong, are of the 

 same description, having undulations alternately above and below 

 the equator; but they differ from one another in the number of the 

 undulations : and some of these require more than one revolution 

 to complete their surface. The properties of the cones and lines 

 thus generated, may be rendered evident by drawing the sections 

 of the cones on the sphere, in perspective, either on a cylindrical 

 or on a plane surface : several examples of which are given in the 

 paper. 



January 13, 1831. 

 JOHN W. LUBBOCK, Esq. V.P. and Treasurer, in the Chair. 



The Earl of Selkirk was elected a Fellow of the Society. 

 The following Presents were received, and thanks ordered for 

 them : — 



Zoological Researches, and Illustrations ; or Natural History of 

 Non-descript, or imperfectly known, Animals, in a Series of Me- 

 moirs. Illustrated by numerous Figures. By John V. Thomp- 

 son, Esq. Vol. 1. Part I. 8vo. — Presented by the Author. 



The Philosophical Magazine and Annals of Philosophy. By R. 

 Taylor, F.L.S. and R. Phillips, F.R.S. No. 49. 8vo. — The Edi- 

 tors. 



Notice of the Proceedings of the Astronomical Society. No. 30. 



8vo. — The Society. 

 Occultations of Planets and Fixed Stars by the Moon, in the year 



1831. Computed for Greenwich by T. Henderson, Esq. 8vo. — 



The Astronomical Society. 

 The National Portrait Gallery. By Wm. Jerdan, Esq. No. 21. 8vo. 



— The Proprietors. 

 The Life -of Sir Humphry Davy, Bart. LL.D. late President of the 



Royal Society. By John Ayrton Paris, M.D. F.R.S. 4to.— The 



Author. 



An Experimental Enquiry into the Number and Properties of the 

 Primary Colours, and the source of Colour in the Prism. By- 

 Walter Crum, Esq. 8vo.- — The Author. 



A Dissertation on the component Parts of an Animal Body. By H 

 W. Dewhurst, Esq. 12mo. — The Author. 



A Synoptical Table of an improved Nomenclature for the Sutures 

 of the Cranium. By the Same. 4th Ed. 12mo. — The Author. 



Remarks in Reply to a Pamphlet by Nicholas H.Nicolas, Esq., en- 

 titled, " Observations on the State of Historical Literature." By 

 Francis Palgrave, Esq. F.R.S. 8vo. — The Author. 



b 2 



