January 6, 1923] 
NATURE 9 

We agree with the statement made in Chapter VIII. 
‘ that there is reason to doubt whether the systematic 
error in the mean levelling of a line, derived from the 
discrepancy between the backward and forward level- 
ling, is a reliable guide to the actual accumulation of 
error within the line.” 
Putting aside such matters as instability of pickets, 
which are clearly capable of producing a systematic 
effect depending on the direction in which the work 
proceeds, the connexion between the remainder of the 
systematic error and the direction does not seem to be 
well established and is a matter which calls for further 
investigation. 
Turning to the equipment which was used for the 
levelling, special attention is due to the staves called 
the ‘‘ Cambridge Staves,” which came into general use 
in 1914. They are described by Lt.-Col. Wolff in 
Chapter II. The novelty of their construction is that 
the graduations are not on the wood of which the body 
of the staff is composed, but on a strip of invar let into 
a groove on the face of the staff. This strip is firmly 
attached to the base of the staff, and is presumably 
kept taut by some arrangement fixed at the top, but 
this detail of the construction is not given. 
The thermal expansion of invar is so small that no 
account has to be taken of changes of temperature, 
which simplifies the computations and adds to the 
precision of the work. Staves of this pattern would be 
still more advantageous in countries where the climate 
is less temperate than it is in England. 
The book is well illustrated, and the closing errors, 
discrepancies, adjustments, and route-profiles of the 
circuits are very clearly displayed in a series of diagrams. 
The work is well produced on the whole, but there are 
signs that the printers were not quite accustomed to 
mathematical symbols with accents, subscripts, etc. 
These are minor blemishes, however, and do not de- 
tract from the great value of this admirable piece of 
work. Gh. 7s ©, 

Scientific Work in the Dutch East Indian 
Seas. 
De Zeeén van Nederlandsch Oost-Indié. Uitgegeven 
door het Koninklijk Nederlandsch Aardrijkskundig 
Genootschap. Pp. ix+507. (Leyden: E. J. Brill, 
1922.) 20 guilders net. 
HIS heavy volume, illustrated with numerous 
photographs and several folding maps, treating 
of our knowledge of the Dutch East Indian seas, is 
published by the “ Koninklijk Nederlandsch Aardrijks- 
kundig Genootschap ” on the occasion of its fiftieth 
anniversary. In it, six specialists give a summary of 
NO. 2775, VOL. 111 | 


the work done in their respective branches of science, 
and the results are worthy of the attention of many 
more than those acquainted with the Dutch language. 
In the first chapter, Col. Honoré Naber gives a 
historical sketch of the research work that has been 
done, beginning with the famous Marco Polo, the first 
European who travelled in those seas in the thirteenth 
century, and whose book was translated into English 
by H. Yule (London, Cordier, 1903). More important 
for us, however, are the expeditions of the last century, 
when the Challenger began the work which was carried 
on by the Szboga and the Balt. 
The second chapter, bringing forward Adm. Tyde- 
man’s work on the depths of the sea, is accompanied 
by a splendid map, showing the extension of the flats, 
as well as the distribution of the curious deep channels 
or troughs, that form one of the most characteristic 
features of this part of the world; for example, the 
Java trough, 6000-7000 metres deep, the Mentawei 
trough, and the well-known Mindanao trough, where 
the greatest depth of the sea, between nine and ten 
thousand metres, is found. 
Then follow accounts’ of investigations on tempera- 
ture, salinity, density, and dissolved gases in the sea 
water, communicated by Prof. Ringer. Many dia- 
grams and tables are a welcome guide in what might 
have been a labyrinth of ciphers. 
An account of the maritime meteorology and the 
tides, written by Dr. van der Stok, and illustrated by 
maps and tables, explains the interesting phenomena 
which tide-waves show in an archipelago, the isles of 
which form numerous obstacles to the movements of 
the water. The theoretical part of this chapter is 
highly interesting. 
Dr. Max Weber’s treatise on the biology of the sea 
is very important, as might be expected from the 
leader of the Siboga expedition. The different zones 
of life in the oceans, the coral reefs, and the conditions 
of deep-sea life are especially treated, and Mrs. Weber- 
Bosse adds an important chapter on plant life in 
tropical seas, which is so absolutely different from our 
coastal vegetation, where only very few Phanerogame 
come down to and into the salt or even brackish water 
of bays and estuaries. 
The next chapter, on the geology of the region, by 
Prof. Molengraaff, is perhaps the most interesting of 
the volume. The writer first points out the remarkable 
difference between the western and eastern parts of the 
Archipelago. The western part, the shallow Soenda 
sea, was dry land during the Glacial period, while in 
the eastern part rows of little islands alternate with 
deep-sea basins, causing a very unequal relief of the 
sea bottom. The theory of the sinking of the sea-level 
and the coral-reef problem, which are narrowly 
