Marcu 28, a 2 | 
NATURE 83 
questions of the pressures on plane and curved 
surfaces, sluice gates and masonry dams, the 
thickness cf pipe walls, and the equilibrium of 
floating bodies are adequately discussed, while 
a brief mention is made of piezometers and dif- 
ferential gauges. 
Chapter v., which introduces the subject 
“fluids in Bian short and rather dis- 
appointing, Bernoulli’s theorem, on which prac- 
tically the whole science cf hydraulics is founded, 
‘being introduced without any attempt at even an 
elementary and approximate proof of its truth. 
Chapter vi. discusses briefly the flow of water, 
‘touching on the questibns of hydraulic gradient, 
‘critical velocity, methcds cf measurement, and 
resistance to flow. In this connection the bald 
statement that in channels the resistance decreases 
with a rise in temperature certainly requires modi- 
fication. In chapters vii. and viii. the Pitot 
tube and the Venturi meter are very adequately 
treated. 
In chapter ix., dealing with orifices, the 
theoretical treatment is anything but scientific. 
‘The method adopted, common in the older text- 
_beoks, consists in assuming that at-all points at 
“the same depth in the plane of an orifice, the 
velocity of efflux is the same, being that corre- 
sponding to the head of water above the point, 
and that the direction of flow at each point is 
perpendicular to the plane cf the orifice. The dis- 
charge so obtained is then multiplied by an em- 
pirical constant to give the true discharge. Both 
assumpiions are fundamentally unscund, and 
although the method leads to the usually adopted 
formule, its limitations should certainly be 
pointed out in any book intended for students. 
The chapter concludes with a good collection of 
experimental data, and is followed by a chapter 
on mouthpieces, including converging and diverg- 
ing tubes, the experimental data in which are not 
quite so up to date. Chapter xi. is devoted to 
a discussion, extending over twenty pages, of 
Freeman’s experiments on fire nozzles. 
In chapter xii. the theoretical treatment of weir 
flow follows on similar lines to that of flow from 
orifices, but this is followed by a well-written dis- 
cussion of the experiments and empirical formule 
of Francis, Bazin, Fteley and Stearns, and Smith, 
and of the United States Deep Waterways experi- 
ments on rectangular weirs. Triangular weirs 
“and the trapezoidal weir are then considered, but 
broad-crested weirs are very briefly dismissed to a 
is able in the appendix. Chapters xiii. and xiv., 
dealing with float and current-meter work, are 
good. 
In chapter xv., the resistances to pipe flow and 
the losses at bends and valves are considered. 
NO. 2213, VOL. 89] 
of 
is very 
crude hunter 
| The various exponential formule for pipe flow are 
practically ignored, the Chezy formula’ being the 
‘only ene to receive detailed attention. 
A good list of experimental data concludes a 
somewhat disappointing chapter. The flow in 
open channels is treated in the next chapter, the 
formule of Chezy, Kutter, and Bazin being well 
discussed. The forms of channel giving best 
results are given, without, however, any proof that 
these really are the best forms. 
Chapter xvii. is devoted to the impact of water 
on fixed and moving vanes, and to water hammer. 
In the latter connection, no attempt is made to 
develop the simple formula for the rise of pressure 
following sudden stoppage cf motion in a rigid 
pipe line, while the statement that the intensity of 
hammer pressures depends primarily on the volume 
of water in the pipe certainly needs amplification. 
The final chapter deals with turbines and centri- 
fugal pumps. The main cutlines of the theories 
of the impulse wheel and of the reaction turbine 
are stated lucidly, and are illustrated with refer- 
ence to actual examples. It was surely, however, 
a mistake to chose the 1895 Fourneyron turbines 
at Niagara for special mention as modern 
machines. The chapter is concluded by a very 
brief discussion, extending over three pages, of the 
centrifugal pump. 
The impression left on the reviewer’s 
ene of unevenness. The treatment cf the funda- 
mental theorems, on which, as a foundation, the 
science is built up, leaves a great deal to be 
desired, and as the book is intended primarily for 
students this is a matter of great importance. 
Those parts of the book which deal with experi- 
mental data are in general good, and in the hands 
of an instructor who would elaborate the founda- 
tion work it should give good results. The book 
is clearly printed and well illustrated. 
Ne els (Ce 
mind is 
A HUNTER IN THE UPPER YUKON ~~ 
RANGES. 
The Wilderness of the Upper Yukon: a Hunter’s 
Explorations for Wild Sheep in Sub-Arctic 
Mountains. By Charles Sheldon. Pp. xxi+ 354. 
(London: T. Fisher Unwin, 1911.) Price 
125. 6d. net. 
HE volume before us is essentially a 
hunter’s book, and will be most appreciated 
by those to whom all incidents of the chase are 
gratifying. Nevertheless, in Mr. Sheldon the 
is blended 
field-naturalist, so that h.s 
often goes beyond the requirements of sport. 
Also, as a hunter, on this occasion he took up the 
réle of specialist, and set out to kill selectively 
and tempered with the 
range of observation 
