6 NATURE 
of Einstein’s theory we can easily find how this varia- 
tion principle must be formulated for systems of 
different nature and also for the gravitation field 
itself” (Proc. Amsterdam Acad., Jan. 30, 1915). 
This is not the place to pursue the contentious view 
(cf. Phil. Mag., Jan. 1923) that the Least-Action dress, 
just because it is so closely interwoven, is like the 
shirt of Nessus, and tends to make havoc of the spatial 
philosophy though without destroying the tentative 
validity of the elegant analytical method. Possibly 
Prof. Lorentz may be tempted to unravel this question 
in his admirable judicial manner. 
In the subsequent years the Proceedings of the 
Amsterdam Academy became a focus for the literature 
of the gravitation theory, mainly in a series of papers, 
apparently first delivered as lectures, by Prof. Lorentz 
himself, in which he develops the tensor scheme in an 
elegant way of his own by a differential geometry 
involving use of infinitesimal loci of constant geodesic 
radius as a kind of indicatrix. Among many other 
papers, doubtless arising from a common inspiration, 
one recalls Droste’s determination, simultaneous with 
Schwarzschild’s solution, of the exact gravitational 
field of a particle, and Nordstrém’s of the field of an 
electron. 
One can look back, still with undiminished surprise, 
at the vast mass of intricate literature on this subject 
which flowed westward, mainly from Berlin and Leyden 
and Géttingen (and also from Italy), when Central 
Europe was again thrown open after the end of 1918. 
The difficulties of a strange though potent and elegant 
calculus could be surmounted by application; but 
the mysteries of unfamiliar meanings and implications 
in imaginary space and time could give rise to abundant 
misconceptions. The uninitiated must still be wary 
in approaching this unexplored and _ treacherous 
domain, in which Prof. Eddington has recently detected 
for us, by beautiful analysis of algebraic tensors, how 
mere co-ordinates are lable to undulate across the 
field on their own account entangled with the gravita- 
tional waves in the underlying spatial reality. 
There is no space to pursue this review of Prof. 
Lorentz’s work further. A survey of his activity is 
a liberal education in the history of physical science 
for the last half-century. Reference to the Proceedings 
of the Amsterdam Academy for the last twenty years, 
in the handsome form of the edition in English, will 
reveal the breadth and informative character of his 
investigations. But this series of volumes is long and 
portly ; and he would confer a great boon on students 
of physical science the world over if he could manage 
to continue the edition of Collected Papers of which 
the first volume appeared in 1907. He will be excused 
the task of reconstruction to bring them up-to-date 
NO. 2775, VOL. 111 | 
[JANUARY 6, 1923 
| which he then essayed, and ‘which perhaps has been a 
cause of the delay. 
Needless to say, Prof. Lorentz has attained to all 
the distinctions all over the world that are appropriate 
for a man of science. He has long been a Foreign 
Member of the Royal Society, and is in the lists of 
Rumford and Copley medallists. For the working 
congresses on the theories of physical science that are 
a feature of our time, he is an almost indispensable 
chairman. Great linguistic gifts, abounding learning, 
clear and rapid grasp of a point of view and prompt 
exposition of it in a different language, ease of approach, 
tolerant appreciation and encouragement of specula- 
tions still unverified, are familiar to his scientific. 
colleagues. We may hope that his time will not be 
diverted overmuch to administrative work such as. 
could be done by others. JosrrpH LaRMoR. 

The Botanical Survey of British Malaya. 
The Flora of the Malay Peninsula. By H. N. Ridley. 
Vol. 1: Polypetale. Pp. xxxv+g918. (London: 
L. Reeve and Co., Ltd., 1922.) 635. net. 
HE Malay Peninsula, for which the opening 
volume of a Flora by Mr. H. N. Ridley has been. 
published “under the authority of the Government 
of the Straits Settlements,” is an important and, save 
for the narrow northern section nearest Siam, a typical 
province of the Tropical Rain-Forest Region. Though 
Europeans secured a footing in this Peninsula four 
centuries ago, the survey of its vegetation was long 
deferred. The Portuguese, who occupied Malacca in 
1511, had done little before their expulsion by the 
Dutch in 1641. The Dutch, who, with two short 
breaks (1795-1801 and 1807-18), owned Malacca till 
1825, scarcely did more. Rumpf, whose “ Herbarium 
Amboinense”’ (1750), completed on September 20, 
1690, surveys the vegetation of the Malay Archipelago, 
avoided dealmg with Malacca. Rumpf regarded the 
Malay Peninsula as belonging to continental India, and 
Valentijn, in his “‘ Oost-Indien”’ (1726), held the same 
view. 
The British became interested in the Peninsula when 
Penang was acquired in 1786. Sir Joseph Banks, 
president of the Royal Society, satisfied the directors 
of the East India Company that a survey of the vege- 
table resources of their territories was essential, and 
in 1793 the Calcutta Botanic Garden was permitted 
to add survey operations to its acclimatisation work. 
The investigation of the vegetation of the Peninsula, 
then begun in Penang, was extended to Malacca when 
that Settlement was first captured from the Dutch in 
1795, and to Singapore when that Settlement was 
