CONTENTS. 



Art. I. On the Geology of Auvergne, particularly in connexion 

 with the Origin of Trap Rocks and the Elevation 

 Theory. By Professor Forbes. Communicated by 

 the Author, ------ Page 1 



II. Questions for Solution relating to Meteorology, Hy- 

 drography, and the Art of Navigation. By M. 

 Arago. (Continued from vol. XX. p. 405,) - 21 



I. Mean height of the Barometer. 2. Of the influence 

 of different winds on the heights of the Barometer, 

 3. On the diurnal variations of the Barometer. 4. Ob- 

 servations on Rain. 5. Rain in a perfectly clear sky. 

 6. Magnetism ; Diurnal variations of the Declina- 

 tion ; Inclinations ; Intensity. 7. Luminous Me- 

 teors ; on Lightning ; Falling-stars ; Zodaical light ; 

 Aurora Borealis ; the Rainbow ; Halos. 8. Pheno- 

 mena of the Sea ; on the means of drawing up Sea- 

 water from great^depths, and discovering in what pro- 

 portion the.two chief constituents of the atmospheric 

 air are contained in it. 9. Marine Currents ; on the 

 cause of Currents ; Sea of Weeds ; Temperature of 

 Currents ; Temperature of the Sea at great depths ; 

 Temperature of Shoals ; Height of Waves ; Visibility 

 of Shoals; Water-spouts; Depressions of the Hori- 

 aon. 10. Miscellaneous Observations ; rising of the 

 Coast of Chili ; Earthquakes ; Declination and In- 

 clination of the Magnetic Needle, ... 67 



III. Observations on the Sense of Touch, including an Ana- 



lysis of Weber's Works on that subject. By Dr 

 Graves of Dublin, ----- 67 



IV. On the Composition of the Water of the Lake Elton 



in Asiatic Russia, compared with the Water of the 

 Ocean and with that of the Caspian Sea. By Mr 



H. Rose, 80 



V. Farther Illustrations of the Propagation of Scottish 

 Zoophytes. By John Graham Dalyell, Esq. 

 Communicated by the Author, - - _ 88 



VI. Letter from Theodore Virlet to M. Arago, on the Phe- 

 nomenon of Dolomisation, and the Transformation 

 of Rocks in general, - - ' -' - - 95 



