CONTENTS. Ill 



PAGE 



Art. XXII. On Spontaneous Re-heating of Air Cooled by Issu- 

 ing, in a Jet, from a more Compressed State. 

 (An important fact, if correct, in regard to the 

 Practical Application of such Variations of Tem- 

 perature.) Also, on the Possible Determination 

 thereby of the Mutual Distances of the Ultimate 

 Atoms of Matter. By William Petrie, Esq., 

 C.E. Communicated by the Author, . . 126 



XXIII. Letter on the Re-heating of Jets of Air, and the 



Relation between Temperature and Compression 

 of the same. By W. J. Macquorn Rankine, 

 C.E., F.R.S.E., 128 



XXIV. On the Origin of Salt and Salt Lakes, . 130 

 XXV. Marie-Henri Ducrotay de Blainville — Dr Pye 



Smith — and M. Beudant, . . . 132 



1. M. H. De Blainville, . . . . 132 



2. Pye Smith, D.D., F.R.S., &c., . . 133 



3. M. Beudant, Member of the French Academy pf 

 Sciences, .... . . 135 



XXVI. The General Distribution of Iodine, . . 136 



Iodine in Aluminous Slates, . . . 137 



Iodine in the Atmosphere — Rain, Dew, and Snow^ 138 

 XXVII. Farther Remarks on the Intermitting Brine Springs 



of Kissingen. By Professor J. D. Forbes, . 139 

 XXVIII. Formulae for Constructing Mr Thomas Stevenson's 

 . Totally Reflecting Hemispherical Mirror. By 

 William Swan, F.R.S.E., F.R.S.S.A. Com- 

 municated by the Royal Scottish Society of Arts, 142 

 XXIX. Suggestions to Astronomers for the Observation of 



the Total Eclipse of the Sun, on July 28, 1851, 154 

 XXX. Meteorological and Astronomical Notices. By Pro- 

 fessor C. PiAzzi Smyth. Communicated by the 



Author 169 



1. On Anemometers. 2. The Trade-wind. 3. The 

 Rotation of the Earth. 4. Eclipse of the Sun in 

 July 28. 5. Source of the Sun's Light and Heat. 

 6. Hind's Planet. 7. Planet Neptune. 8. Saturn's 

 Dark Ring. 9. Lassel's Reflector. 10. Comet of 

 Biela. 11. New Meridian Instrument at Greenwich. 

 12. Oxford Observatory, . . 169-189 



