438 
THE FORECAST OF THE MONSOON. 
HE brief telegrams that have lately been published 
from India concerning the amount of rainfall have 
given a very uncertain note. Favourable and unfavour- 
able accounts have followed in rapid succession, and at 
the moment of writing it seems doubtful whether to 
expect a normal amount of precipitation, or to dread a 
recurrence of one of those calamitous famines, which 
drain so severely the resources of India, and from the 
last of which she has barely recovered. In these cir- 
cumstances, it is of more than usual interest to turn to 
the official forecast, to see how the causes, which in the 
opinion of the best-informed meteorologists affect the 
climate of India, are operating for and against the 
prospects of a successful harvest. 
At the outset we meet with a grave disappointment. 
The Simla authorities distinctly express their inability to 
make a forecast, on any scientific ground, of two very 
important factors which affect the agricultural value of 
the monsoon rainfall. These are the possibility of the 
occurrence of a protracted break in the rainfall during 
the months of July and August, even after the season has 
opened favourably, and of an unusually early termin- 
ation of the rains in the North and Central Provinces of 
India and in Bengal. For fifteen years the Meteor- 
ological Office has deplored the want of the necessary 
data that would warrant a prediction on these important 
topics, and there are no signs that the information will 
be forthcoming at an early date. As a matter of fact, 
the authorities go little further than an examination of 
the conditions under which the south-west monsoon 
currents will arrive on the coasts of the peninsula. It is 
true that the probable amount of rainfall in the various 
provinces of India is considered at some length, but it is 
expressly declared that this “forecast is a statement of 
probabilities, and not of certainties, and that it is lable 
to error from the limitation and uncertainty of part of 
the data on which it is based.” 
Similar words accompany all the forecasts that prudent 
men venture to make, and it must be admitted that the 
continual repetition is wearisome and distressing. Such 
a caution may be necessary, but if it produces on the 
mind of an impatient public the impression that little or 
no advance is being made in meteorology, and _particu- 
larly Indian meteorology, a great injustice is done toa 
body of highly-skilled observers, who have not spared 
themselves to benefit science, to improve the lot of the 
agriculturist, and to strengthen the hands of the Govern- 
ment in dealing with a misfortune they are eager to 
alleviate, but powerless to avert. 
But it is not difficult to see some of the reasons that 
compel the staff to halt at the result of this preliminary 
investigation. Forecasting, as understood in England, 
and which practically rests on the capacity of the tele- 
graph to outrun the storm or the weather it announces, 
would be valueless in India. Away from the coasts and 
outside shipping interests, there is no necessity for daily 
forecasting, nor for the study of those ephemeral fluctu- 
ations which go to make up our weather. On the other 
hand, the meteorological conditions that result from the 
movement of enormous masses of the air attract greater 
scientific attention, owing to their periodic character and 
the effect likely to be produced on agriculture and the 
well-being of large masses of the population. It would 
be wrong, however, to forget that in late years, and 
mainly under the energetic direction of Mr: Eliot, 
barometric variations, however small in amount, have 
been studied with good effect, and have revealed the 
probable existence of cyclical variations which can have 
1 ‘Memorandum on the Snowfall in the Mountain Districts bordering 
Northern India, and the Abnormal Features of the Weather in India: with 
a Forecast of the S.-W. Monsoon Rains of 1899.” By John Eliot, Meteor- 
ological Reporter to the Government of India, and Director-General of 
Observatories in India. (Simla: June 1899.) 
NO. 1558, VOL. 60] 
NATURE 
[SEPTEMBER 7, 1899 
considerable influence in promoting or checking the 
general oscillatory motion of the air across the equator, 
to which motion the south-west and north-east monsoon 
winds are mainly due. 
But in the forecast before us, though the variations of 
pressure from the normal, and the effect.such fluctuations 
have on the local weather existing in India immediately 
preceding the advance of the monsoon, are treated as a 
factor in the problem, two other conditions have naturally 
great weight. These are the amount and time of occur- 
rence of the snowfall in the mountain districts adjacent 
to Northern India, and the behaviour of the south-east 
trades in the preceding season, as investigated at 
Seychelles, Mauritius, the Cape of Good Hope, and 
the logs of ships passing over the area affected. Such 
latter information is of necessity incomplete, but is likely 
to be of great importance in proportion as it covers a 
larger area, for the greater the district brought under 
review, the greater the probability of tracing the true 
physical cause on which important variations rest. It 
may not be out of place, as showing the wide extent over 
which meteorological phenomena extend themselves, and 
the consequent necessity for the examination of all remote 
causes to which they may be traced, to recall the ap- 
parent connection existing between the barometric oscil- 
lations in the Indo-Malayan region on the one hand, and 
Russia and Siberia on the other. Further, we have some 
evidence of connection between the south-east rains of 
South Africa and the amount of the rainfall at the time 
of the summer monsoon, while the overflow of the Nile 
seems to participate in similar periodic variations. Such 
general disturbance tends to point to a common cause, 
and it is gratifying to know that the possibility of the 
connection has been pointed out by the Indian meteor- 
ological officers, who are fully alive to the importance 
of discovering the origin of these effects, which demon- 
strate themselves periodically. In basing the forecast on 
more or less local appearances, we seem to recognise the 
weak point in long-period forecasting. Weare in the 
position of a physician who deals with the symptoms 
rather than the origin of a disease. 
This difficulty of trusting to appearances may be illus- 
trated in many ways. For instance, how are we going to 
estimate the relative importance of the two operating 
factors we have mentioned above, the snowfall on the 
Himalayas and the behaviour of the south-east trades ? 
And how are we going to act if we find the indications 
from the two sources discordant? Some time since we 
believe that the snowfall was regarded as the one im- 
portant item in the making up of the forecast. Scanty 
rain was anticipated as the consequence of heavy snow, 
but greater experience has somewhat discredited the 
notion. Late snow in April or May, or the cause which 
produces the late snowfall, no doubt does exercise very 
considerable influence locally on the distribution of the 
monsoon winds ; but when we have to deal (as already 
pointed out) with the effects produced by the circulation 
of an atmosphere covering an entire hemisphere, such 
local results play but an insignificant part. Nevertheless, 
we find Mr. Eliot, who doubtless is glad to avail himself 
of every source of information, carefully tabulating the 
time and amount of the snowfall from Afghanistan on the 
West to Assam in the East. But, in drawing his con- 
clusion, he does not leave out of sight the local character 
of the indication, and a distinction is drawn between the 
conditions that should follow the reports from Western 
India and those received from the Eastern Himalayas. 
In the former case, the signs point to an early and strong 
monsoon with beneficial results to the utmost limits of 
the Punjab. The conclusions to be drawn from the ac- 
counts from the eastern portion are more uncertain both 
on account of deficiency in the data received and greater 
doubt in the interpretation of the sign, but it is expected 
that the rainfall in North-east India will be diminished, 
