SUPPLEMENTARY REPORT ON METEOROLOGY. 105 
ready been mentioned, which serve to explain the more formal 
modifications of wind by a combination of the principles of 
rarefaction by heat, and the mechanical rotation of the globe. 
The particle of air, thus drawn toward the equatorial regions 
by the rarefaction permanently produced there by the sun’s 
verticality, lags behind the parallel of latitude over which it 
moves, having the velocity due to a higher latitude from which 
it has come. That there must be a return current is not only 
evident to common sense, but its existence is made evident by 
the drift of clouds in the neighbourhood of the tropics, and by 
observations at great elevations ; not to mention that the preva- 
lent S. and S.W. winds of our latitudes appear to be nothing 
else than portions of this superior return current, which, in this 
stage of its progress, falls again to the surface of the earth, pos- 
sessed of the excess of velocity of a more southern parallel. 
202. These doctrines are now generally held, but there have 
been various attempts made to carry out the theory and to ge- 
neralize the facts further, even as respects the apparently capri- 
cious changes of wind in this most anomalous region of the 
earth’s surface. It even appears probable that our forefathers 
knew more on this subject than is generally admitted now, 
and the sagacious guesses of the seventeenth century may be 
brought in support of the probable theoretical conjectures of the 
nineteenth. 
203. Professor Dove, of Berlin, author of several original re- 
searches in meteorology, optics, and magnetism, and editor of a 
valuable scientific work of reference*, has published a series of 
elaborate memoirs more or less connected with the theory of 
wind}, of which he has more lately published a compend f, but 
whose labours on this subject seem to be little, if at all, known 
in this country. This perhaps is to be attributed to the want 
of a perspicuous analysis of his views by some one who would 
undertake clearly to state, how far they are original and how 
far combined from those of others, how far they are to be con- 
sidered hypothetical and how far founded upon demonstration. 
We feel the want of some such guide in turning over Prof. Dove’s 
three hundred and forty-four closely-printed pages, and also in 
the writings of his countrymen who have acted as commen- 
tators§. Iam by no means satisfied that I am so thoroughly 
possessed of his views as to give all that Prof. Dove claims to 
* Repertorium, of which 3 volumes are published. 
+ Alist of 14 memoirs contained in Poggendorff’s Annals between the 
11th and 36th vols. will be found in his “ Untersuchungen,” p. viii. 
t Meteorologische Untersuchungen, von H. W. Dove. Berlin, 1837. 8vo. 
§ Fechner, in his Repertorium, vol. iii.; Kamtz, in his Meteorologie, i, 254; 
Mahlmana, in his enlarged Translation of my last Report, p. 155. 
