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"be so in the January chart in the case of the North Pole ; and the fact that 
north-east winds are reported from Iceland and Greenland, proves the 
existence of high pressure in the high latitudes. 
Turning to Mr. Lowe’s pamphlet, we find that he starts with the 
assumption which every meteorologist seems so disposed to admit, yet finds 
so difficult to substantiate, viz. that a cycle of the seasons exists, though its 
precise period has yet to be ascertained. Mr. Lowe himself is satisfied that 
the cycle is about eleven years, thus agreeing with the Sun-spot theorists 
(though throughout the book there is no reference to sun-spots, or to this 
agreement), while at the same time he considers that at every ninth cycle 
the phenomena are much intensified. 
An extraordinary amount of trouble has undoubtedly been expended in 
the compilation of this work, and the authorities being quoted, an immense 
assistance is thereby afforded to any one continuing the investigations. That 
further investigations are needed is, unfortunately, most true, for we find 
that during the past six centuries fifteen droughts were accelerated one 
year, and nine were retarded one year, while six were accelerated two years, 
and four retarded a like period. This compels us, in giving a forecast, to 
allow a margin of four years for possible eventualities, a margin which is 
much too large to give the forecast a practical value. This value may, 
however, very shortly be tested, as Mr. Lowe considers that with last 
October there commenced three years of drought and frost, a forecast 
which every succeeding day will go to prove or refute. 
HEAT* 
P ROF. TYNDALL’S well-known treatise on the mechanical theory of 
heat has now been out of print for a considerable time, so that the 
appearance of this sixth, revised and enlarged edition, will be welcomed by 
many students. Founded as it is upon his lectures delivered at the Royal 
Institution, and retaining the lecture form in its chapters, while the numerous 
experiments which the Professor delights to bring before his audiences are 
copiously illustrated by figures of apparatus in use, the style in which the 
information is conveyed to the reader has a freshness and vigour about it 
hardly attainable by any drier mode of treatment, and one is at no loss to 
understand the great popularity that this book has so long enjoyed. In his 
new edition Prof. Tyndall has evidently been careful to work in the most 
recent results of physical researches in the somewhat wide field that he 
undertakes here to open up to his readers, his book, as is well known, dis- 
cussing a host of phenomena with which heat is more or less immediately 
concerned. 
* Heat a Mode of Motion. By John Tyndall, D.C.L., LL.D., F.R.S. 
Sixth Edition. 8vo, London : Longmans, 1880. 
