FEBRUARY II, 1904] 
NATURE 
353 
Out of twelve maxima of storms, ten coincide with 
maxima periods of spots. Out of five minima of storms, five 
coincide with minima of spots. 
It will be seen that the results from both the East and 
West Indies are the same. Next came the question of a 
rainfall cycle corresponding to the solar spots (‘‘ Solar 
Physics,’’ Lockyer, 1874, p. 425)- 
When I was preparing to go to India, in 1871, to observe 
the eclipse, Mr. Ferguson, the editor of the Ceylon Observer, 
who happened to be in London, informed me that everybody 
in Ceylon recognised a cycle of about thirteen years ‘or so 
in the intensity of the monsoon—that the rainfall and cloudy 
weather were more intense every thirteen years or so. This, 
of course, set one interested in solar matters thinking, and 
I said to him :—‘‘ But are you sure the cycle recurs every 
thirteen years, are you sure it is not every eleven years? ” 
adding, as my reason, that the sun-spot period was one of 
eleven years or thereabouts, and that in the regular weather 
of the tropics, if anywhere, this should come out. 
It afterwards turned out that the period in Ceylon was 
really of eleven years, five or six years dry and five or six 
years wet, and that a longer period of about thirty-three 
years was recognised. : 
Mr. Meldrum passed from cyclones to rainfall by a very 
obvious step, because cyclones are generally accompanied 
by torrential rains. A study of the rainfalls of Port Louis, 
Brisbane, and Adelaide led him to the conclusion that a 
case had been made out for a supposed periodicity. 
On my return from India I looked up the Cape and 
Madras records for the periods available, and found that 
they followed suit, hence I quite agreed with Dr. Meldrum 
that investigations were desirable, and I wrote as follows 
( Solar Physics,’’ pp. 424-5) :— 
“Surely in meteorology, as in astronomy, the thing to 
hunt down is a cycle, and if that is not to be found in the 
temperate zone, then go to frigid zones, or the torrid zones 
and look for it, and if found, then above all things, and in 
whatever manner, lay hold of, study it, record it, and see 
what it means. If there is no cycle, then despair for a 
time if you will, but yet plant firmly your science on a 
physical basis, as Dr. Balfour Stewart long ago suggested 
before, to the infinite detriment of English science, he left 
the Meteorological Observatory at Kew; and having got 
such a basis as this, wait for results. In the absence of 
these methods, statements of what is happening to a 
blackened bulb in vacuo, or its companion exposed to the 
sky, is, for research purposes, work of the tenth order of 
importance.”’ 
With reference chiefly to Dr. Meldrum’s paper, I added :— 
“Surely here is evidence enough, evidence which should 
no longer allow us to deceive ourselves as to the present 
state of meteorology. A most important cycle has been dis- 
covered, analogous in most respects to the Saros discovered 
by the astronomers of old, indeed, in more respects than 
one, may the eleven yearly period be called the Saros of 
meteorology, and as the astronomers of old were profoundly 
ignorant of the true cause of the Saros period, so the 
meteorologists of the present day are profoundly ignorant 
of the true nature of the connection between the sun and 
the earth. 
“What, therefore, is necessary in order to discover the 
true nature of this nexus? Two things are necessary, and 
they are these. In the first place, we must obtain an 
accurate knowledge of the currents of the sun, and secondly 
we must obtain an accurate knowledge of the currents of 
the earth. The former of these demands the united efforts 
of photography and spectrum analysis, and the second of 
these demands the pursuit of meteorology as a_ physical 
science, and not as a mere collection of weather statistics. 
When these demands are met—and in spite of the Mrs. 
Partingtons who are endeavouring to prevent this, they will 
soon be met—we shall have a science of meteorology placed 
on a firm basis—the meteorology of the future.”’ ane 
At this time the Indian authorities were quite alive to 
the importance of such investigations as these. India is in 
ee I very much regret that, in the article quoted, my reference to Carlyle’s 
3serman ‘* Dry as dust,’ as a patient inquirer who would eventually appor- 
Hon credit to all meteorological workers, has been misunderstood by some 
2 my German friends. Relying on imperfect dictionaries, which have told 
them that a mere ‘‘bookworm” was meant, they have missed the high 
compliment I intended to pay them. 
NO. 1789, VOL. 69] 
the tropics, India is a child of the sun, the inhabitants de- 
pend almost entirely upon the beneficent rains which 
seemed, in some way or another, to depend upon solar action. 
India also had then the germs of one of the best equipped 
meteorological organisations which exist on the surface of 
the planet, and the meteorologists felt that there was some- 
thing behind their meteorological registers which might be 
assisted by taking a very official step and going to head- 
quarters, headquarters being the sun. When I was in 
India in 1872, Lord Mayo, the then Viceroy, did me the 
honour to ask me to go to Simla with the view of choosing 
a site for a proposed solar physics observatory. That is 
thirty years ago! Unfortunately, | was secretary of the 
Duke of Devonshire’s Commission, which was then sitting, 
and I could not get leave, and therefore could not go; the 
scheme, which was then before the Indian authorities— 
which, if | may say so, was altogether grandiose and ex- 
travagant—fell through. 
In 1873 the idea of the possible connection of solar and 
magnetic changes had got so far that the magnetic and 
meteorological department of the Royal Observatory at 
Greenwich, which had been established in 1838, received 
an important addition. A photoheliograph was set up in 
order to continue the daily photographic record of the sun’s 
surface, begun at Kew in 1865. 
In the same year Képpen found that the maximum 
temperature occurs in the years of sun-spot minima and the 
reverse; years with many spots are cool years.’ 
Of special importance for the connection between the 
temperature on the earth's surface with the sun’s spotted 
area is the fact that the temperature curve (mean number 
for the whole earth) and the curve representing the sun- 
spotted area are identical in all the irregularities. 
In the tropics in the 
Year before the sun-spot Min., the temperature is 0-41° 
higher than the mean. 
Year before the sun-spot Mavx., the temperature is 0-32° 
lower than the mean. 
The variation is thus 0-73°. 
By this time spectroscopic observations of the solar 
changes had proved that the sun was hottest when there 
were most spots, thereby upsetting the old idea that the 
spots acted as screens and reduced the radiation at sun-spot 
maximum. K6ppen’s result, therefore, was a paradox, and 
was thus explained by Blanford (Bengal, Asiat. Soc. 
Journ., 1875) :— 
“The temperatures dealt with by Prof. Koppen are of 
course those of the lowest stratum of the atmosphere at 
land stations, and must be determined not by the quantity 
of heat that falls on the exterior of the planet, but on that 
which penetrates to the earth’s surface, chiefly to the land 
surface of the globe. The greater part of the earth’s sur- 
face being, however, one of water, the principal immediate 
effect of the increased heat must be the increase of evapor- 
ation, and, therefore, as a subsequent process, the cloud 
and the rainfall. Now a cloudy atmosphere intercepts the 
greater part of the solar heat, and the re-evaporation of 
the fallen rain lowers the temperature of the surface from 
which it evaporates and that of the stratum of air in contact 
with it. The heat liberated by cloud condensation doubt- 
less raises the temperature of the air at the altitude of the 
cloudy stratum; but at the same time we have two causes 
at work, equally tending to depress that of the lowest 
stratum. As a consequence, an increased formation of 
vapour, and therefore of rain, following on an increase of 
radiation, might be expected to coincide with a low air- 
temperature on the surface of the land” (see also Blan- 
ford, Nature, April 23, 1891, vol. xliii. p. 583). 
The next important advance had to do with atmospheric 
pressure. In 1875 Mr. F. Chambers, the director of the 
Bombay Observatory, found that 
‘““The variation of the yearly mean barometric pressure 
at Bombay shows a periodicity nearly corresponding in 
duration with the decennial sun-spot period ’’ (Meteorology, 
Bombay Presidency, August, 1875, S. 26, p. 12). 
The years round 1875 were rendered very important by 
the number of new organisations established to record and 
1 W. Képpen, “Uber mehrjahrige Perioden der Witterung ” (Zeitschrift. 
J. Meteorologie, Bad. viii., 1873, pp. 241-248 and 257-268), 
