X CONTENTS. 



Eemarks on the Coal plant termed Stigmaria. By the Rev. Dr 

 Fleming, . . .... 316 



On Errors caused by Imperfect Inversion of the Magnet in Obser- 

 vations of Magnetic Declination. By William Swan, Esq., . 318 

 On the Accuracy attainable by means of Multiplied Observations. 

 By Edward Sang, Esq., . . . . . 319 



On the Occurrences of the Plague in Scotland during the Sixteenth 



and Seventeenth Centuries. By Robert Chambers, Esq., . 326 



On a Problem in Combinations. By Professor KeUand, . 326 



Occurrence of Native Iron in Liberia, in Africa. From a Letter of 



Dr A. A. Hayes, Chemist, Boston, U.S., to Professor H. D. 



Rogers. Communicated by Dr Gregory, . . • 327 



Geological Notes on Banffshire. By R. Chambers, Esq., F.R.S.E., 332 

 On the Physical Geography of the Old Red Sandstone Sea of the 



Central District of Scotland. By Henry Clifton Sorby, F.G.S. 



Communicated by Professor Balfour, .... 334 

 Remarks by Professor Christison in delivering the Keith Medal to 



Dr Anderson of Glasgow, ..... 337 

 Geometry a Science purely Experimental. By Edward Sang, Esq., 341 

 Notice respecting recent Discoveries on the Adjustment of the Eye 



to Distinct Vision. By Professor Goodsir, . . . 343 



Memoir of Rear-Admiral Sir John Franklin. By Sir John 



Richardson, C.B. Communicated by Professor Balfour, . 347 



On the Geological Relations of the Secondary and Primary Rocks 



of the Chain of Mont Blanc. By Professor Forbes, . . 348 



On the Turkish Weights and Measures. By Edward Sang, 



Esq., . . . . . . . .349 



Observations on Polyommatus Artaxerxes, the Scotch Argus. By 



Dr W. H. Lowe, . . . . . .349 



On Solar Light, with a Description of a Simple Photometer. By 



Mungo Ponton, Esq., ..... 355 



On Certain Cases of Binocular Vision. By Professor William B. 



Rogers, Communicated by Professor Kelland, . . 356 



Theory of the Free Vibration of a Linear Series of Elastic Bodies. 



Part I. By Edward Sang, Esq., . . . .358 



Observations on the Diatomaceous Sand of Glenshira. Part II. 



Containing an Account of a number of additional Undescribed 



Species. By William Gregory, M.D., F.R.S.E., Professor of 



Chemistry in the University of Edinburgh, . . . 358 



Theory of the Free Vibration of a Linear Series of Elastic Bodies. 



Part n. By Edward Sang, Esq., . . . .360 



An Account of some Experiments en certain Sea- Weeds of an 



Edible kind. By John Davy, M.D., F.R.SS., Lond. and Edin., 363 

 On the Deflection of the Plumb-Line at Arthur's Seat, and on the 



Mean Density of the Earth. By Lieutenant-Colonel James, R.E. 



Communicated by Professor Forbes, . . • . 364 



On the Possibility of Combining two or more Independent Proba- 

 bilities of the same Event, so as to form one Definite Probability. 



By Bishop Terrot, ...... 366 



On Atmospheric Manoscopy, or on the direct Determination of the 



