g is as far to
the right as to the left. Each generation lives through a part of one,
or two, or even three oscillations. A snapshot view of these
oscillations makes them seem permanent. As Supan has well said, it was
formerly believed that climate changes locally, but progressively and
permanently. It is now believed that oscillations of climate are limited
in time, but occur over wide areas.

LITERATURE.--Scientific climatology is based upon numerical results,
obtained by systematic, long continued, accurate meteorological
observations. The essential part of its literature is therefore found
in the collections of data published by the various meteorological
services. The only comprehensive text-book of climatology is the
_Handbuch der Klimatologie_ of Professor Julius Hann, of the
university of Vienna (Stuttgart, 1897). This is the standard book on
the subject, and upon it is based much of the present article, and of
other recent discussions of climate. The first volume deals with
general climatology, and has been translated into English (London and
New York, 1903). Reference should be made to this book for further
details than are here given. The second and third volumes are devoted
to the climates of the different countries of the world. Woeikof's
_Die Klimate der Erde_ (Jena, 1887) is also a valuable reference book.
The standard meteorological journal of the world, the _Meteorologische
Zeitschrift_ (Braunschweig, monthly), is indispensable to any one who
wishes to keep in touch with the latest publications. The _Quarterly
Journal of the Royal Meteorological Society_ (London), _Symons's
Monthly Meteorological Magazine_ (London), and the _Monthly Weather
Review_ (Washington, D.C.) are also valuable. The newest and most
complete collection of charts is that in the _Atlas of Meteorology_
(London, 1899), in which also there is an excellent working
bibliography. For the titles of more recent publications reference may
be made to the _International Catalogue of Scientific Literature
(Meteorology)_. (R. DE C. W.)

CLIMATE IN THE TREATMENT OF DISEASE.--The most important qualities of
the atmosphere in relation to health are (i.) the chemical composition,
(ii.) the solids floating in it, (iii.) the mean and extreme
temperatures, (iv.) the degree of humidity, (v.) the diathermancy, (vi.)
the intensity of light, (vii.) the electrical conditions, (viii.) the
density and