NATURE 
THURSDAY, AUGUST 7, 1902. 
HANN’S METEOROLOGI/E. 
Lehrbuch der Meteorologie. Von Dr. Julius Hann, Pro- 
fessor an der Universitat in Wien. Mit 111 abbild- 
ungen im text, 8 tafeln in lichtdruck und autotypie, 
sowie 15 karten. (Leipzig: Chr. Herm. Tauchnitz, 1901.) 
HIS remarkable book had its origin in a suggestion 
by the publishers that Dr. Hann should write a text- 
book of meteorology for students. As the author himself 
points out, it has travelled far beyond its original object, 
and as it stands it constitutes substantial ground for in- 
creased gratitude to Dr. Hann from meteorologists of all 
countries, by whom he has long been recognised as a 
master in the subject. The book is a veritable encylo- 
pzedia of meteorological science. It consists of 792 pages 
of text, and each page is made up of small type, smaller 
type and smallest type. The small type gives the pro- 
fessor’s current narrative ; the smaller type gives a large 
number of technical details ; the smallest type embodies 
a most valuable series of references with critical notes ; 
and the whole constitutes a complete representation of 
the present position of meteorological science apart from 
those climatological details which are given in Dr. Hann’s 
well-known “ Climatologie.” 
The arrangement of the book is on physical lines. 
After a general introduction, temperature in all its 
relations, pressure, moisture, wind phenomena and 
dynamical meteorology, z.e. the meteorology of atmo- 
spheric disturbances, are successively treated, while an 
appendix gives some of the most important of the 
mathematico-physical theories of meteorology. 
One striking feature which illustrates the wide range 
of the book is the number of distinguished physicists 
and chemists whose researches have contributed to the 
development of meteorological science and whose 
papers are quoted or referred to. Among English 
physicists the names of J. W. Strutt, Lord Rayleigh, 
Lord Kelvin, Stokes, Osborne Reynolds, Shelford Bidwell, 
W. Ramsay, J. J. Thomson, Abney, Schuster, Oliver 
Lodge, Poynting, all appear as responsible for various 
meteorological contributions, and a similar list of names 
might be adduced for other countries. It may surprise 
physicists generally to learn how many of their dis- 
tinguished colleagues are referred to in a work which 
deals with the present state of meteorology adequately. 
It is satisfactory evidence that meteorology has not yet 
drifted out of touch with modern physics. 
The arrangement is so skilful that every page of the 
book is full of interest. It takes a thoroughly rational 
and impartial view of all meteorological theories and 
speculations, gives an account of the results derived from 
the discussion of most voluminous meteorological obser- 
vations, and in spite of the huge mass of material with 
which it deals it manages to keep the reader’s attention. 
It is, indeed, difficult to read because it is so full of matter 
and so skilfully arranged that the reader is hardly willing 
to regard one page as exhausted and to go on to the next. 
The illustrations are all most carefully selected, excel- | 
lently reproduced, and some of them are impressive 
examples of the possibilities of photographic reproduction | 
NO. 1710, VOL. 66] 
Jo 
in what may be called the department of the natural 
history of the atmosphere. They make one wonder 
whether it is not really an advantage for other depart- 
ments of natural history and for the public that their 
specimens are so unwieldy that they must be broadly dis- 
played in a suitable museum instead of being neatly 
folded away in books and stored on the upper 
floors of an office. No doubt Dr. Hann, who for 
so many years has been in touch with meteorologists of 
all countries, is in a position of special advantage in 
regard to the work of compiling such a book, but when 
all his advantages are taken into account the reader 
cannot help being amazed at the skill and judgment with 
which the organisation of the facts has been carried out. 
Whether one deals with the variation of meteorological 
elements from hour to hour, from day to day, from month 
to month or from year to year, the statistical results are 
so clearly and concisely expressed and the salient features 
so well marked by special type or other devices that the 
reader can draw his own conclusions with ease. To take 
a trivial example, on p. 335 we find statistics of the 
diurnal distribution of rain. Those who are interested 
in such matters may see at a glance that at Kew in 
summer the most unfavourable hours for a garden party 
are from 2 to 4 in the afternoon, and next to those from 
4 to 6, when the frequency of rain is about half as much 
again as it is between 6 and 8a.m., whereas in winter 
from 4 to 6 is the best time of the day from the point of 
view indicated. On the other hand, at Valencia the 
frequency of rain from 4 to 6 in the afternoon in summer 
is not much more than half the frequency at the cor- 
responding morning hours. 
‘the work is brought very closely up to date. The 
most recent developments of the study of the upper 
atmosphere by means of kites, balloons and clouds are 
noted, and some of the results of the simultaneous 
balloon ascents under the auspices of the International 
Aéronautical Committee are included. 
In dealing with the physical aspects of meteorology 
the author exhibits the same comprehensive grasp of the 
subject and the same conciseness of style as when dealing 
with the direct results of observation, but here the reader 
may find himself at fault. The science requires a know- 
ledge, not only of meteorological facts, but of the physical 
and chemical theory which is necessary for the appro- 
priate coordination of the facts. The author briefly in- 
corporates all contributions to the science, and naturally 
when he makes use of physics or chemistry or mathe- 
matics he does not stay to develop the necessary intro- 
ductory study of those sciences. The consequence is 
that many concise and comprehensive sentences require 
a considerable amount of antecedent knowledge for their 
full appreciation. As an example of the rapidity with 
which subjects are passed under review, I quote the para- 
graph which deals with the selection of the thermometric 
scale, as follows :— 
“Die Fahrenheitsskala ist noch in allen Landern 
englischer Zunge, selbst in wissenschaftlichen Werken 
iiblich. Als ein Vorteil derselben wird angefihrt dass 
man weniger mit negativen Graden zu rechnen hat und 
dass der Grad kleiner ist, weshalb es vielfach geniigt die 
Temperatur nur in ganzen Graden anzugeben,” 
with the footnote, 
