100 
Now all this egregious contrast between human society, as 
well as the flora, on the one side, versus the other, of Southern 
Africa (excepting some details dependent on the soil and the 
prevailing direction of the wind) are due to the Indian Ocean 
imparting to the air on the east coast an invisible, yet most 
potent quality which the Atlantic does not confer on the western 
coast. Could there then be found a more expressive emblazon, 
suitable to the present day, for a coat of arms for one of the 
flourishing new Governments on the eastern side of South 
Africa, than a wet, and dry, bulb hygrometer pictured with both 
bulbs marking 85° F., and with the surf of the Indian Ocean 
beating in the distance? C, PIazzi SMYTH 
May 29 
The Composition of the Edible Bird’s-Nest 
As I have been much interested in the controversy concerning 
the composition of the edible bird’s-nest, and particularly in the 
bearing of Mr. Green’s investigations, which are given at length 
in your last issue (p. 81), would you permit me to give the result of 
some observations I made on this subject in the Solomon Islands. 
It will be remembered that it was the association of these nests 
with a so-called ‘*fungoid growth” in the caves of North Borneo 
that led Mr. Pryer to consider that he had found the source of 
the material of which the nests are made, a supposed discovery | 
which led to the re-opening of the controversy (NATURE, 
vol. xxx. p. 271). This low plant-substance was determined by 
Mr. George Murray to be the result of the growth of a micro- 
scopic alga, a species, probably new, of Gleocapsa (Proc. Zool. 
Soc., 1884, p. 532)- 
In the Solomon Islands I was only able to obtain the edible 
nest in one locality (Oima Atoll) since the bird usually frequents 
inaccessible sea-caves and cliffs. The nests were of inferior 
quality, and were for the most part composed of fibrous materials 
derived from the vegetable drift (the husks of pandanus seeds 
especially). The gelatinous substance thickly incrusted the in- 
terior of the nests, and attached them to the rock. The surface 
of a cliff in the vicinity of the cave frequented by the swifts was 
coated by a reddish gum-like growth, which proved on exami- 
nation to be an aggregation of the cells of a protophytic alga 
about 1/2500 of an inch in size. Unfortunately my specimens 
of this growth have miscarried, but I feel assured that it is very 
similar to that observed by Mr. Pryer in the Borneo caves, 
samples of which, through the kindness of Mr. George Murray, 
I had the opportunity of seeing at the British Museum, A 
similar growth is commonly to be found coating the coral-lime- 
stone cliffs in this group, It may be seen in all stages, the older 
portions being dark-coloured and rather tough, and the fresher 
portions being, as Mr. Pryer aptly remarked, like half-melted 
gum tragacanth. There are but few cells in the fresh alga, the 
mass being apparently composed of cellular debris, immersed in 
a rather diffluent material, the whole somewhat resembling the 
third section given in Mr. Green’s paper. 
That the salivary glands are especially concerned in the pro- 
duction of the gelatinous nest-substance there can now be but 
little doubt, and the investigations of Mr. Green have established 
the nature of its composition ; yet it is possible, and I make the 
suggestion with great diffidence, that a vegetadle mucin, or a sub- 
stance closely allied to this animal product, may be found in these 
low plant-growths. H. B. Guppy 
95, Albert Street, N.W., May 29 
“* Arithmetic for Schools ” 
In NaTuRE of May 20 (p. 51) there appears a criticism of 
my ‘‘ Arithmetic for Schools,” in which your reviewer states :— 
“‘In the purely arithmetical part of the book logical accuracy is 
attempted with considerable success. Want of grasp is much 
more evident in the part which deals with the applications. 
Then the division into subjects is strangely illogical, and slight 
inaccuracies of thought and language occur. Is it really the case, 
for example, that rate of interest (p. 181) is totally independent 
of time?” These are very serious charges to make against a book 
of the kind, and ought not to be made without very good rea: on. 
As your reviewer suggests the inferences (1) that the book is 
divided into parts, one of which contains the “‘pure arithmetic,” 
and the other the ‘‘ applied,” and (2) that it is stated that ave of 
interest ts totally indefendent of time, and as neither of these 
inferences has any foundation in fact,. it seems only fair to myself 
NATURE 
| of the sunspots, and the further 
i 
[Fune 3, 1886 
that your reviewer should be asked to quote verbatim the other 
slight inaccuracies on which he bases his general statement. 
Gonville and Caius College, May 24 Joun B. Lock 
SUNSPOTS AND PRICES OF INDIAN FOOD- 
GRAINS 
jpBs the volume of the Bomdbay Gazetteer which deals 
with the province of Kathiawar, there is at page 217 
a long list of prices of the principal food-grains at Bhay- 
nagar. The list contains, along with other information, 
the price of Indian millet for nearly every year from 1783 
to 1882. This series of figures is long enough to afford 
the means of testing whether there is any tendency, in 
India, for times of scarcity, and consequent dearness of 
food, to recur after more or less regular intervals of 
years. 
Ever since the discovery by Schwabe of the periodicity 
discovery by Sabine of 
the same periodicity in the variations of the earth’s 
magnetism, there has been a growing belief in the minds 
of scientific men that the varying condition of the sun 
exerts a far greater influence on terrestrial affairs than is 
usually thought at all probable, and various investigators 
have traced, with more or less definiteness, a periodicity 
of eleven years—coinciding with that of the sunspots—in 
the variations of the rainfall, in those of the temperature 
and pressure of the atmosphere, and in the frequency of 
storms, &c. The late Prof. Stanley Jevons went so far 
as to express the opinion that even trade depressions — 
are the remote effects of corresponding variations in the 
condition of the sun. 
I am not aware that any attempt has hitherto been made 
to trace out any direct connection between the variations — 
of prices in India and solar phenomena. The apparent 
hopelessness of the task has probably acted as a sufficient 
deterrent, for although it may be reasonable to suppose 
that solar variations influence the rainfall and other purely 
physical phenomena, yet it is well known that there are 
many causes of variation of price which cannot, with any 
show of reason, be attributed directly to the sun. Such, 
for instance, are wars, the gradual increase of the popula- 
tion, variations in the quantity of money in use, changes 
in the total volume of trade, &c. These circumstances 
complicate the problem very much, but it does not neces- 
sarily follow that it is hopeless to attempt to trace the 
possible influence of solar periodicity on the prices; for 
there are statistical methods by which most of the dis- 
turbing influences can be approximately, if not entirely, 
eliminated. Indeed, when these methods of elimination 
have been applied, it may be found that the solar periodi- 
city is more decidedly traceable in the prices than in the 
rainfall: for, in the one case, the produce of every field 
exercises its due share of influence in determining the 
price ; while, in the other case, the quantity of rain actually 
measured is but an infinitesimal portion of the whole 
quantity which falls, and may therefore very imperfectly 
represent the total rainfall over the whole of a district. 
In considering a price in relation to the causes of varia- 
tion to which it is subject, it may be thought of as divided 
into portions, each portion being assigned to its own 
particular cause. What is wanted here is to separate as 
distinctly as possible that portion which may be due to 
the variation of the influence of the sun from all the rest. 
But before any satisfactory attempt can be made to dis- 
tinguish that portion of the price variation which may be 
due to variation of solar influence from the portion due 
to the average amount of solar influence and to other 
causes, it is necessary to adopt some standard of com- 
parison which may reasonably be supposed free from solar 
effects of a periodically variable nature. Now as the — 
physical state of the sun is known to go through a com- 
plete cycle of changes in a period of almost exactly eleven 
years, the average price for any consecutive eleven years’ 
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