650 
edly an advantage, for the lower adjustment requires 
always great nicety in the observer, and is, in some kinds 
of light, really difficult; but the advantage is, in our 
opinion, more than counterbalanced by the complexity 
of the reductions necessary for the instruments, which 
obviously require an additional correction for the change 
of level in the cistern. 
The thermometers, maximum and minimum, dry and 
wet bulb, are described in the same exhaustive manner, 
and the best methods are discussed for obtaining trust- 
worthy observations on the temperature of air, springs, 
rivers, and soils; the tension of the vapour of the atmo- 
sphere, and hence the relative humidity of thelatter. Dr. 
Jelineck erroneously states on page 41 (foot-note No. 4), 
that the mean temperatures in England and Scotland are 
solely derived from the readings of the maximum and 
minimum thermometers. It is quite possible that in 
former years such observations, for want of better ones, 
were made the basis for deducing the mean temperature 
of some localities ; but, as far as we are aware, these are 
exceptional cases, and the daily and annual mean tem- 
peratures are everywhere in this country derived from 
daily observations at fixed hours. 
The remainder of the work comprises chapters On rain- 
gauges, the direction and force of wind, anemometers, 
the amount and form of clouds, the direction of upper 
currents, thunderstorms, optical phenomena of the atmo- 
sphere, ozone observations, and finally, the best methods 
for deducing from the observations the most probable 
annual mean results. Although the author shows him- 
self, on the whole, well acquainted with what has been 
done in this branch of physical science beyond Germany, 
some of the chapters alluded to appear defective. A great 
deal of scientific knowledge and mechanical ingenuity 
have been brought to bear in this country on many of the 
subjects just mentioned, and our observatories, both public 
and private, are now supplied with instruments for different 
purposes, with which those described by Dr. Jelineck will 
bear no comparison ; indeed, his instructions with reference 
to them, show that very little advance has been made in 
this respect from an almost primitive state: and if we con- 
sider what use is being made in this country of photography 
for obtaining continuous records of the principal atmo- 
spheric phenomena, and how well founded our hopes are 
thus, at last, to obtain an insight into the great laws which 
must regulate these phenomena,—we cannot but regret 
that the wide experience and profound knowledge of 
continental meteorologists should remain unsupported by 
the invaluable assistance of our modern appliances in 
their scientific investigations. The attentive reader will 
nevertheless find treasures even in those parts which fall 
short of our expectations, for every page is replete with 
most valuable hints, instructions, and suggestions, derived 
from long and extended experience. 
The second part consists of very numerous and highly- 
valuable auxiliary tables, some of which, especially those 
referring to hypsometrical observations, we do not recol- 
lect to have met before in such a compact form. 
No allusion whatever is made to solar radiation and 
atmospheric electricity, two meteorological elements the 
importance of which is rising more and more in the esti- 
mation of all thoughtful meteorologists. 
NATURE 
[April 28, 1870 
We learn with satisfaction that the metrical system will 
shortly be introduced in Austria and Hungary, and that 
in future the Centigrade scale will be made use of in the 
meteorological observations. Bo: 
OUR BOOK-SHELF 
The Home Life of Sir David Brewster. 
Daughter, Mrs. Gordon. 
WE like this book. It is notoriously difficult for a near 
relation to write a truthful biography, but Mrs. Gordon 
has done her work with great ability, taste and judgment. 
To most readers, the family details at the beginning will 
be of little interest, but as the life advances the interest 
grows. The book is essentially what its title imports, 
it pictures Sir David as a man rather than as a 
philosopher ; yet his daughter tells us much of when and 
how his literary and scientific work was accomplished, 
and gives us lively anecdotes both of himself and of 
many of his contemporaries. In one chapter she analyzes 
his mental characteristics, and while acknowledging his 
imperfections, she shows that much which appeared 
inconsistent in his actions arose from an uusually dual 
nature, the continuation of a_ peculiarly impulsive 
temperament, with a scientific habit of thought. In 
another, she traces his religious history, and we see his 
advance from a somewhat cold and rigid orthodoxy to a 
living and happy faith, when without materially changing 
his own opinions he was ready to sympathise with good 
men who differed from him. Those who are well 
acquainted with the multitudinous optical researches of 
Brewster, will enjoy a glimpse of him at work among 
apparatus, often extemporised from corks and bits of 
metal, and glass, meanwhile indulging in a low purring 
whistle of satisfaction, and those who remember him 
only as a Nestor in science with furrowed features and 
snowy hair, describing his discoveries, or declaring his 
convictions in clear vehement language, will like to 
know him also as the head of a family, and the principal 
of a university, a politician, and a writer of reviews, 
gaining high distinctions, and promoting valuable 
institutions. But we can only just: indicate these things, 
and must refer to his daughter’s book for details about 
the dawn full of promise, the brillant noonday, and the 
beautiful sunset of his life, 
By his 
J. H, GLaDsTonE 
On the Rotation of the Embryoes of the Frog within 
the Egg. By Dr. S. L. Schenk. Pfliiger’s Archiv. 
1870, ili. Jahr., Heft 2 and 3. 
IT is well known that the embryo of the frog exhibits 
remarkable movements of rotation, the direction being in ~ 
opposition to that of the movements of the hands of a 
watch, supposing the observer to be looking vertically 
down upon the instrument, and that the head of the 
animal is directed away from him. These movements 
continue without interruption, and may be watched for 
hours together. They vary considerably in rapidity, but 
a series of observations made by Dr. Schenk showed 
that the rotation was effected in from five minutes and 
thirteen seconds to twelve minutes and two seconds. It 
has not been accurately ascertained when these move- 
ments commence, since in the earliest stages of develop- 
ment the surface of the egg is in close contact with the 
capsule, and it is only after some water has been imbibed 
that the two are separated, but Dr. Schenk shows that 
they result from the presence of ciliated cells on the sur- 
face; first, because these can be demonstrated with the 
microscope; secondly, because they can be accelerated 
by the application of moderate heat, which is well known 
to render the movements of cilia more rapid, and thirdly, 
because they can be arrested almost instantaneously by 
the action of weak acids, which are known to operate in 
the same way on ciliary movements. 
