AUvGUST 7, 1902]| 
NATURE 341 
the properties of these polygons and shows how, 
by their use, the shearing and bending actions, lines 
of resistance, &c., due to given loads may be deter- 
mined. The drawing of link polygons so as to lie within 
given loaded arch rings is explained, and applied to the 
determination of the so-called line of least resistance of a 
masonry arch. The deflections of beams are next con- 
sidered, and the link polygon method is extended and 
applied to the plotting of the elastic curves of loaded 
beams, including continuous beams. The latter were 
treated in vol. i. by the aid of the theorem of three 
moments. The student has thus the advantage of a 
comparison of the two methods. 
Nearly a fourth part of the text is thus occupied in 
establishing the fundamental properties of the link and 
vector polygons, and then the author, in the second part, 
which comprises the remainder of the work, and is divided 
into three sections, proceeds to the practical applications. 
Section i. deals with the stability and design of tall 
chimneys, buttresses, and various forms of cranes. 
In Section ii. the subject of earth pressure is very 
fully considered, and examples are given of the design of 
retaining walls to resist the pressure of earth, and of 
masonry dams for reservoirs. 
“Structures that span an interval” is the heading to 
the concluding Section iii. ; and here the author treats 
very fully of masonry arches, fixed and continuous 
girders, cantilever bridges, stiffened suspension bridges, 
hinged metal arches, &c. 
In an appendix a partial reprint is given of a paper by 
Colonel A. Cunningham on well foundations, which should 
prove of special interest to students and engineers in 
India, where, in spanning many of the rivers, the founda- 
tions have to be laid in quicksand. 
It seems an unfortunate omission that in so excellent 
a treatise no reference is made to the application of the 
strain-energy method and the principle of least work to 
calculations on the deflections and stresses in braced 
frames, structures with redundant members, arched ribs, 
&c. ; but otherwise the treatment is quite up to date. 
As regards practical construction, information is given as 
to the design of many details; and some examples of 
complete designs are fully worked out, and illustrated by 
drawings, taken principally, by permission, from Colonels 
Wray and Seddon’s “ Instruction in Construction.” There 
are numerous folding plates, facilitating reference and 
allowing the figures to be drawn to a large scale. 
The treatise can be recommended as a useful book of 
reference for engineers in the pursuit of their profession. 
Students whd master the details of both volumes should, 
in the subjects of which they treat, be well equipped for 
their duties of after life. 
OUR BOOK SHELF. 
Ordnance Survey of England and Wales. 
miles to I inch, or 1 :253,440. 
Is. 6d. 
THIS sheet is a specimen of the new quarter-inch map of 
the British Isles which is being issued by the Ordnance 
Survey at Southampton, and we have pleasure in recog- 
nising in it many marks of the vitality of the Survey and 
of its power of employing the most modern methods to 
meet new requirements. The old quarter-inch map of 
NO. 1710, VOL. 66] 
Scale 4 
Sheet iv. Price 
Ireland in four huge sheets was a masterpiece of en- 
graving and of printing directly from the plate ; the old 
quarter-inch map of Scotland was a somewhat hapless 
attempt to show rivers in blue on an outline very sketchily 
printed from transfers in black, while the old quarter-inch 
map of England was a clear outline with fine lettering 
but little detail, the antiquity of which was thrown into 
painful relief by the insertion of railways up to a modern 
date. The new quarter-inch map of Great Britain, now in 
course of publication, is up to date in all particulars, and 
beautiful as well as accurate. The sheets are of convenient 
size (24 in. x 16 in.), the edges graduated to single minutes 
of latitude and longitude, with the meridians and parallels 
for each 20’ drawn clearly across the map, thus greatly 
facilitating the plotting of any distribution which - has 
been worked out on maps of a larger scale, an advantage 
which will appeal to every geographical worker. The 
names and general detail are printed in black, the size of 
the lettering nicely graduated to show relative importance, 
and the style of execution is worthy of the best traditions 
of the old one-inch map. Railways are shown in a strong 
black line, county boundaries in a distinct dotted line, 
and roads of three classes are distinguished, the first 
class having the usual indication as to fencing and being 
coloured solid brown. Rivers and other water surfaces 
are given in blue, and when the altitudes marked on in 
bold black figures are considered the surface would appear 
to be so fully occupied that nothing could be added. 
Here, however, the chief novelty and beauty of the map 
appears. The configuration of the country is shown by 
a hill shading so expressive and unobtrusive that it 
actually seems to make more room for the other features, 
by throwing each into its own proper place and fixing it 
there. The blue threads of the water-courses accentuate 
the valleys of the high moorlands, the roads and railways 
are fitted with a pictorial commentary explanatory of 
every curve ; even the county boundaries, so arbitrary on 
common maps, are seen to be natural lines, now a main 
watershed, again a powerful river. Colonel Johnston 
deserves the utmost credit for his bold and successful 
experiment in expressing relief without the use of con- 
tours or of hachures by the half-tone photographic re- 
production of washes of colour. The hill-work is printed 
in brown, with which the blue of the water and the black 
of the names and railways contrast equally, and even the 
green with which extensive woodlands are shown stands 
out well. 
The technical production leaves nothing to be desired, 
and we confidently place this map before any other in 
the world on the same scale for beauty of finish, accuracy 
of execution and sound judgment in the selection of 
features and names. It will be invaluable for mapping 
the distribution of phenomena in many branches of 
science, and welcome also to the tourist and motorist. 
A Manual of Elementary Practical Physics. By Julius 
Hortvet, B.S. Second edition. (Minneapolis: H. W. 
Wilson, 1902.) 
“ LIFE is not long enough to admit of a vedzscovery of the 
fundamental laws of physics. Besides . . . some of the 
laws were not discovered through experiment at all, but, 
on the contrary, were obtained by pure reasoning and 
afterwards verified by experiment.” 
This quotation will show that the author is not an 
adherent of the out-and-out heuristic school. But while 
it is not expected that a pupil shall go through the 
necessarily slow process of acquiring a// his know- 
ledge by his own investigations, he is expected to think 
for himself while the chain of reasoning to be followed 
and the conclusions to be drawn are indicated by ques- 
tions which the pupil has to answer. While in sympathy, 
in the main, with this method, we do not think that the 
questions are always very happily chosen. Thus after 
experiments on the bending of a lath and the stretching 
