FEBRUARY I1, 1904] 
NATURE 355 
for every day except two. It is easy to understand that 
with such a magnificently complete record as this the study 
of solar physics was enormously improved. 
Very fortunately for science, even before these steps were 
being taken to secure a continuous record of the spotted 
area, Prof. Respighi (1869) and Prof. Tacchini (1872) had 
commenced at Rome a daily record of the solar promin- 
ences and of the latitudes at which they appeared at different 
times. 
I pass on to some of the most important work done during 
the last quarter of a century, only referring to the results 
obtained which bear upon the connection between solar and 
terrestrial changes. 
Many important advances were made in 1878. 
Mr. F. Chambers, in continuing his studies on the Indian 
barometer, found (Nature, vol. xviii. p. 567) a remarkable 
degree of resemblance in the progression of barometric 
pressure during summer, winter, and year, and sun-spots 
from year to year, but he noted that the barometric curve 
lags behind the sun-spot curve, particularly in the years 
of maxima of sun-spots. The winter curve is more regular 
than the summer one, probably because the weather 
generally in India is more settled in the winter than in the 
summer, but on the whole the two curves support each 
other in having a low pressure about the time of sun-spot 
maximum, and a high pressure about the time of sun-spot 
minimum. We may therefore conclude that the sun is 
hottest about the time when the spots are at a maximum. 
He added that these results appear to harmonise well with 
the decennial variations of the rainfall in India, and to 
throw light upon the inverse variation (compared with the 
sun-spots) of the winter rainfall of northern India. 
Dr. Allan Broun also, in a discussion of Indian baro- 
metric readings, found that the years of greatest and least 
pressure are probably the same for all India, and that, 
therefore, the relation established by Mr. Chambers for 
Bombay holds for all India (Nature, vol. xix. p. 6). 
I next pass to rainfall. Dr. Meldrum, returning to his 
rainfall studies, found that (NaTuRE, vol. xviii. p. 565) 
“There is a remarkable coincidence between the rainfall 
and sun-spot variation at Edinburgh, much more remark- 
able than that at Madras. The years of maximum and 
minimum rainfall, and sun-spots for the mean cycles, 
coincide, and on the whole there is a regular gradation 
from minimum to maximum, and from maximum to the 
next minimum.”’ 
The minimum rainfall occurred, on an average, in the 
year immediately preceding the year of maximum sun-spots. 
The results of these investigations show that the rainfall 
of fifty-four stations in Great Britain from 1824-1867 was 
0-75 inches below mean when sun-spots were at a minimum, 
and o-go inches above mean when sun-spots were at a 
maximum. 
For the thirty-four stations in America, the corresponding 
numbers were 0-94 inch and 1-13 inch. 
In the report of the Meteorological Department of the 
Government of India, published this year (1878), the follow- 
ing reference to solar action occurs :— 
“The following are the main important inferences that 
the meteorology of India in the years 1877-1878 appears to 
suggest, if not to establish :— 
‘There is a tendency at the minimum sun-spot periods 
to prolonged excessive pressure over India, and to an un- 
usual development of the winter rains, and to the occur- 
rence of abnormally heavy snowfall over the Himalayan 
region. . This appears also to be accompanied by a 
weak south-west monsoon.”’ 
In 1880 the relation of Indian famines and the barometer 
was first fully treated by Mr. F. Chambers, the meteor- 
ological reporter for western India (Nature, vol. xxiii. p. 
109). He concluded from his inquiry that there is some 
intimate relation between the variations of sun-spots, 
barometric pressure, and rainfall, and as famines in 
general are induced by a deficiency of rain, it is probable 
that they also may be added to the above list of connected 
phenomena. 
Commencing with the daily abnormal variations observed 
at several stations in western India, it was found that as 
the time over which an abnormal barometric fluctuation 
extended became longer and longer, the range of the fluctu- 
NO. 1789, VOL. 69] 
ation became more and more uniform at the various stations, 
thus leading to the conclusion that the ‘‘ abnormal vart- 
ations of long duration affect a very wide area.’’ For 
testing this, the conditions of Batavia were compared with 
those at Bombay, and the results showed a striking co- 
incidence, the curves obtained for the two places being 
almost identical in form, but with this remarkable difference, 
the curve for Batavia was found to lag very persistently 
about one month behind the Bombay curve. 
Similar results were then worked out for other stations, 
St. Helena, Mauritius, Madras, Calcutta, and Zi-ka-wei. 
On comparing the curves obtained for these various places, 
though a strong resemblance in form between all the curves 
is observed, there is also strong evidence of a want of 
simultaneity in the barometric movements at different 
stations, and as a rule the changes take place at the 
more westerly stations several months earlier than at the 
more easterly ones. 
Thus on comparing the curves for St. Helena and Madras 
from 1841-1846, the latter sometimes lagged behind the 
former as much as six months, and for Bombay and Calcutta 
the corresponding difference was often upwards of six 
months. 
The facts suggested to him long atmospheric waves (if 
such they may be called) travelling at-a very slow and 
variable rate round the earth, from west to east, like the 
cyclones of the extra-tropical latitudes. 
With special reference to famines, he remarked that, on 
comparing the dates of all the severe famines which have 
occurred in India since 1841, widespread and severe famines 
are generally accompanied or immediately preceded by 
waves of high barometric pressure. He suggested, there- 
fore, that intimation of the approach of famines might be 
obtained in two ways :— 
(a) By regular observations of the solar spotted area and 
early reductions of the observations, so as to obtain early 
information of current changes going on in the sun. 
(b) By barometric observations at stations differing 
widely in longitude, and the early communications of the 
results to stations situated to the eastward. 
In the same year, Dr. H. F. Blanford discovered that 
(Nature, vol. xxi. p. 480) 
““ Between Russia and Western Siberia on the one hand, 
and the Indo-Malayan region on the other, there is a re- 
ciprocating and cyclical oscillation of barometric pressure, 
of such a character that the pressure is at a maximum in 
Western Siberia and Russia about the epoch of maximum 
sun-spots, and in the Indo-Malayan area at that of minimum 
sun-spots.’”’ 
Up to 1881, the general idea had been that there was a 
great difference between the meteorological conditions at 
the maximum and minimum of the sun-spot curve, but the 
more numerous and more accurate series of observations 
available in the year in question revealed to Meldrum 
“extreme oscillations of weather changes in different places 
at the turning points of the curves representing the increase 
and decrease of solar activity.”’ 
This was a most important change of front. Not the 
maximum only, but both the maximum and minimum had 
to be considered (‘‘ Relations of Weather and Mortality, and 
in the Climatic Effect of Forests ”’). 
In relation to these pressure changes Blanford wrote as 
follows (Nature, vol. xxi. p. 482) :— 
““Among the best established variations in terrestrial 
meteorology which conform to the sun-spot cycle, are those 
of tropical cyclones, and the general rainfall of the globe, 
both of which imply a corresponding variation in evapor- 
ation and the condensation of vapour. Now the variation 
of pressure with which we have to deal evidently has its 
seat in the higher (probably the cloud-forming) strata of 
the atmosphere. This is not only illustrated in the present 
instance by the observed relative excess of pressure at the 
hill stations as compared with the plains, but also follows 
as a general law from the fact established by Gautier and 
K6ppen, viz., that the temperature of the lowest stratum 
varies in a manner antagonistic to the observed variation 
of pressure. It is then a reasonable inference that the 
principal agency in producing the observed reduction of 
pressure at the epoch of sun-spot maximum is the more 
copious production and ascent of vapour, which may operate 
