700 
planting Marram-Grass and Tree-Lupin are 
discussed in detail and suggestions are in- 
cluded for the post-planting management of 
the plantations. The possibility of checking 
sand movement by means of sand-fences and 
protection belts is considerably elaborated. 
Protection belts are merely narrow bands of 
Marram set at the junction of the advancing 
sand and the invaded ground. Such a belt is 
efficient usually for only a few years unless it 
is constantly watched and repaired. 
The report closes with a discussion of 
afforestation of the dunes, which method 
seems to the author to be the only means of 
establishing the desired static condition over 
the dune complex. Little tree-planting upon 
the dunes has been done in New Zealand 
under difficult conditions, but the method is 
strongly recommended. The more important 
trees and shrubs for dune afforestation in 
these islands are as follows: Olearia Traversii, 
Pinus pinaster, Pinus halpensis, Araucaria 
excelsa, Cupressus macrocarpa, Pinus radiata 
(most valuable), Pinus muricata, Tamariaz 
gallica, Lupinus arboreus, Acacia melanoxylon, 
Salix caspica, Populus deltoides, Populus 
balsamifera, Populus fastigiata and Alnus 
glutinosa. Besides these species, all of them 
promising dune holders, Pinus laricio, P. 
pinea, P. Coultert and P. Strobus grow 
“ quite well” on the dunes of New Zealand. 
A final list of plants (over 200 species) suit- 
able for dune cultivation in these islands con- 
tains useful information as to the habitat, 
growth-form, ete., for the various species, 
many of which are North American. 
This very interesting and well-written paper 
is well illustrated by means of sixty-nine half- 
tones and three etchings, and includes a bib- 
liography of sixty-six general works and seyv- 
enty-three references to the literature of New 
Zealand Dunes. 
Raymonp J. Poon 
THE UNIVERSITY OF NEBRASKA 
Aerial Navigation. A Popular Treatise on the 
Growth of Air Craft and on Aeronautical 
Meteorology. By Apert F. Zanm. New 
York, D. Appleton & Co. 1911. S8vo. Pp. 
SCIENCE 
[N.S. Vou. XXXV. No. 905 
xvii +497; 58 illustrations in text and 32 
full page plates. 
Amid the flood of ephemeral popular and 
pseudo-scientific books on this subject which 
have appeared in England and America dur- 
ing the past two years, here is one that rests 
on a solid foundation, fit to carry the super- 
structure of subsequent progress. The author, 
distinguished as a pioneer investigator of 
aerodynamics in America, has been intimately 
acquainted with Langley, Chanute and the 
Wrights, and a close student of aeronautics in 
Europe. Therefore Dr. Zahm is eminently 
qualified to write a book, which in character 
resembles the reviewer’s earlier and smaller 
“ Conquest of the Air,” a revised edition of 
which Dr. Zahm’s later and more detailed pub- 
lication seems to render superfluous. How- 
ever, the most recent achievements in aero- 
nautics chronicled in any book are already 
antiquated and surpassed when presented to 
the reader and conclusions based thereon re- 
quire corresponding modification. 
Authors naturally give prominence to those 
subjects with which they are most familiar 
and, therefore, while the reviewer accorded 
first place to the Ocean of Air, Dr. Zahm puts 
Aeronautical Meteorology last, having com- 
piled this section largely from other authors 
and thereby somewhat neglected its status in 
this country. The two preceding divisions of 
the book are: the Growth of Aerostation, in 
which both spherical and dirigible balloons are 
considered, and the Growth of Aviation, treat- 
ing of early attempts to fly, the modern glider 
and the power aeroplane.. An appendix con- 
tains technical papers and three letters of 
Benjamin Franklin, written from Paris in 
1783 describing the first balloons, which are 
reprinted from “The Conquest of the Air.” 
The author refrains from prophecies concern- 
ing future developments of craft either 
lighter or heavier than air, since progress in 
the art of aerial navigation has been so rapid 
as to baffle conjecture concerning their ulti- 
mate applications. 
In conclusion, it may be said that the work 
ean be recommended, to either the lay or 
scientific reader, as admirable in its material 
