August 31, 1889. 
THE GARDENING WORLD. 
835 
TO TELL THE WEATHER. 
A correspondent writes : —In reference to the recent 
stormy weather, and the happening of storms of unusual 
severity, it may be mentioned that Benjamin Franklin 
was the first to discover that storms in America tra¬ 
velled from west to east. He was interested in 
observing an eclipse, and found that while the obser¬ 
vations were spoiled in Philadelphia by a rain-storm 
that came on just at the beginning of the eclipse, the 
sky was clear at Boston until after the eclipse was over. 
By communicating with intervening towns he learned 
that the storm travelled eastward at a uniform rate. 
Simultaneous observations taken in all parts of the 
country show that nearly all great storms follow the 
same general direction—from 
the west to the east. The 
same is true of cold or hot 
waves. Therefore, to tell 
what the weather will be in 
advance we have only to 
find out the conditions 
prevailing west of us. This 
is practically the course 
pursued by the signal 
service. 
The direction of a storm 
is frequently diverted by 
some local cause. A low 
barometer or larger amount 
of moisture in the air attracts 
a storm, and may either 
change its course entirely, 
or hasten its advance. The 
rate at which a storm travels 
between two points is, in 
fact, calculated by the 
gradient or decline of the 
barometer from one point to 
the other. When a storm is 
advancing the wind blows to 
meet it. Thus a wind blow¬ 
ing from the east or south¬ 
east indicates the approach of 
a storm from the west. 
When the storm centre has 
passed, however, the wind 
changes and follows the 
storm. If a person has a 
good barometer and wind 
guage he can tell pretty 
correctly when a storm is 
coming. Without these in¬ 
struments the clouds may be 
watched, and when seen to 
be moving rapidly from the 
south-east, and there are in¬ 
dications of much moisture 
in the air, a storm is not 
far away. The old Scotch 
saying that— 
“A red sky at night is the 
shepherd’s delight, 
A red sky in the morning, 
shepherds take warning,” 
while regarded as generally 
true in the United Kingdom, 
is said to be only partially 
true in the United States of 
America. The red sky in 
the morning indicates an 
excess of moisture in the 
air, and a storm is therefore 
likely to occur before many 
days. 
The circle round the moon 
—a lunar rainbow—shows 
the presence of moisture in the air. Moisture at a 
high altitude produces a large bow, and at a low 
altitude a small bow. The smaller the bow, therefore, 
the nearer is moisture, and consequently the sooner 
will the storm develop. The old saying that the 
number of stars to be seen inside the circle indicates 
the number of days before the arrival of the storm is 
not reliable, as the position of the moon in the heavens 
may make the number great or small without regard 
to the storm conditions. All attempts at predicting 
the weather for months in advance are only guess¬ 
work. Such superstitions as trying to foretell the 
severity of a winter by the thickness of the breastbone 
of the goose, or the fur of animals, originated in some 
obscure quarter, and are not worth the circulation and 
attention they receive. 
PLUMBAGO CAPENSIS ALBA. 
The white-flowered variety of the well-known Plum¬ 
bago capensis flowers as freely as the type, and under 
the same conditions. The beauty of both as climbers 
in the greenhouse cannot well be gainsaid, but they 
never appear to more advantage than when brought 
together by way of contrast, for the white is as pure as 
the pale blue of the other is constant. One of the 
peculiar features of this plant is the different temper¬ 
atures in which it may be grown to perfection and 
appear quite at home. For instance, it may be grown 
as a climber for covering the roofs of stoves, inter¬ 
mediate or ordinary greenhouses. The flowers may 
not last so long when grown in a high temperature, 
Sarracenia Wrigleyana. 
but they can be had earlier in the season, or even twice 
a year, by cutting back the side shoots after flowering 
is over, and encouraging fresh growth. In a greenhouse 
where the temperature is not allowed to fall below 45° 
or 50° in winter an early and very abundant crop of 
bloom may be had. 
A more recent use to which Plumbago capensis 
has been put is summer-flower bedding, and when 
the branches have been pegged down and come 
into bloom the pale blue flowers have a distinct and 
pleasing effect, as much on account of their novelty as 
anything else. The white variety would no doubt 
flower as well, but unless the two kinds were mixed 
the white alone would not be so effective or conspicuous. 
Both forms are flowering freely in the nursery of Messrs. 
J. Laing & Sons, Forest Hill. 
BLUE HYDRANGEAS. 
Hydrangea hortensis, blue and pink, have long 
been understood as identical, but it must be confessed 
that there is something rather complex in connection 
with the cause which changes the colour from pink to 
deep blue. I have observed it several times stated 
that potting in peat, and adding oxide of iron to the 
soil, would effect this change. This I have tried as 
late as this year, with the usual negative results. I 
cannot say that so far as I have experimented with 
different soils, with a view to changing the colour, any 
alteration in the hue was noticed. Iron, I am almost 
certain, does not in the least affect the colour, for the 
loam I am in the habit of potting with at present 
contains a large percentage 
of the red oxide. I cannot, 
therefore, vouch with any 
degree of confidence that 
what I have been taught to 
regard as one variety is so, 
yet in every other point 
no other difference can be 
detected to even presume that 
they are distinct varieties. 
A rather strange thing, 
perhaps, in connection with 
the colouration of these 
plants, is that it is more 
often met with grown 
as window plants or out of 
doors than when under 
glass. 
I have not seen a blue- 
flowered plant grown under 
glass for years, though I 
have no doubt it is not a 
rare thing ; still, it is the 
exception and not the rule. 
This would lead us to 
suppose that the pink is the 
normal colour, and the blue 
the abnormal. Chemical 
ingredients in the soil may 
assist in effecting a change 
in flower colour under un¬ 
natural circumstances—that 
is, when it is compelled to 
imbibe, for the want of some 
other, any such substance ; 
but, then, surely this can¬ 
not take place without 
materially affecting the con] 
stitution of a plant. I 
must not be understood to 
insinuate that a plant will 
absorb into its system any 
substance whatever, for, as 
is well known, such would 
be inconsistent with the 
theory of absorption. Alum, 
for instance, is alleged to 
be effectual in changing the 
pink Hydrangea to blue. 
This can only be by some 
detrimental effect that Alum 
must have on the spongi- 
oles and finer roots, thus 
incapacitating them for some 
time from performing their 
action and supporting the 
healthy character of the 
plant. Such a check, no 
doubt, if applied at the 
proper time, would more than 
likely have some influence 
on the flower. Alum is not 
taken up by plants, but decomposition will set free the 
sulphate of potash it contains, and after another process 
of oxidation, is changed into the nitric form, and then 
readily assimilated. The sulphate of alumina, the other 
part of the compound alum, is left behind, and to all 
intents and purposes has no direct value in the plant’s 
food supply. Potash, the chief constituent of plant 
structure, is supplied in abundance from many sources, 
in the same form as when alum is applied, and no 
change of colour in flowers arises from its excess. 
Such being the case, it appears to me that it is a 
matter of grave doubt whether chemicals play any very 
important part in the colouration of the Hydrangea. 
I would prefer to assume that it is more attributable to 
drainage, atmospheric qualities, a morbid condition of 
the roots brought about by a cold ungenial soil, and an 
