168 
POPULAR SCIENCE ITEWS. 
[November, 1891. 
Various geological forces liave played their part 
in these transformations; the shrinking of the 
earth's crust and the volcanic foi-ces beneath have 
caused the land to rise and fall above or below 
the sea level; the astronomical motions of the 
earth in its annual journey around the sun have 
caused the climate to cliange from time to time; 
and perhaps even changes in the radiant energy 
of the sun itself have not been without their 
effect upon the earth. But above all other agen- 
cies the little rain-drop, insignificant by itself but 
mighty in numbers, has accomplished more than 
any other agency in the successive transforma- 
tions which the face of the earth has undergone. 
A single rain-drop falling upon a mountain top 
produces no appreciable effect, but it nevertheless 
does something. It may move a grain of sand 
from its place, or even set a pebble In motion 
towards the valleys below ; and the countless 
millions of rain-drops which follow it in succeed- 
ing ages will tinally succeed in wearing the moun- 
tain top away. As they roll down the mountain 
side, they gather into rivulets, brooks, and tor- 
rents, and their erosive force becomes greatly 
increased by gravitation. Another drop may fall 
into a crevice in the rock, there to remain until it 
expands in the act of freezing, and splits off a 
fragment, which in its turu is carried down to 
lower levels. Or pei-haps the rain-drop falls as a 
snow-flake, which, with many others, is in time 
consolidated into an ice-tield and glacier, which 
ploughs down the mountain side, crushing and 
grinding the rocks as it goes, into a form which 
can readily be transported to lower levels by the 
streams of water formed by its melting. 
Or perhaps the rain-drop falls upon a limestone 
formation. A little — a very little, but still a defi- 
nite quantity — of the hard rock is dissolved and 
carried away to the ocean, or deposited in a 
distant locality by the evaporation of the water. 
The amount dissolved by a single rain-drop is 
almost infinitesimal, but the great caverns found 
in all parts of tlie world owe their origin to 
nothing but this solvent power of innumerable 
drops of water. Even the hard, enduring granite 
will finally crumble away, one of its constituent 
minerals, feldspar, being decomposed and changed 
into clay. The erosive power of running water 
and the chemical action of still water supplement 
and aid each other in their great work. 
That the streams and rivers of the more level 
districts are continually lowering the level of the 
land is evident to every one. The bars which are 
formed at the mouths of rivers are only the earth 
which has been washed down from higher regions 
by the rushing rain-drops, and the level of the land 
is constantly being lowered, and, in many cases, 
perceptibly so by this means. If any proof were 
needed of the action of this force in past times it 
would be found in the fossilized rain-prints, 
where the impressions made in soft mud by the 
drops of some ancient storm have been hardened 
into stone, and preserved to us so perfectly that 
we can tell from what direction the wind was 
blowing in that shower of millions of years ago. 
There is still another indirect way in which the 
rain-drop takes part in the action of geological 
forces. One would hardly associate the presence 
of water with a volcanic eruption; but water is 
always present, and doubtless plays a most im- 
portant part in the phenomena of volcanic ac- 
tivity. Volcanoes are always found near the 
seacoast, and the presence of immense volumes of 
steam is always observed during an eruption. 
Contrary to the popular idea, neither flame nor 
smoke proceeds from the crater of a volcano, but 
only quantities of melted mineral matter, or lava. 
and immense volumes of steam. It was this pasty 
mass of finely pulverized lava — incorrectly called 
ashes — and water which overwhelmed the city of 
Pompeii and sealed it up for nearly two thousand 
years. Actual fire played a very small part in the 
destruction of that ill-fated city. There can be 
no doubt that water and the internal heat of the 
earth form a combination which will explain 
nearly all manifestations of volcanic forces ; and 
so the rain-drop is shown to play another part in 
the geological transformations. 
In short, we may say that every particle of 
matter above the sea level, except in regions 
where rain never falls, is constantly moving, 
slowly but surely, towards the ocean, and has 
been ever since the land was first raised above 
the water. In past ages the action of subterra- 
nean forces has raised the ocean beds and turned 
them into dry land, hills, and mountains, only to 
be once more returned to their native element. 
We cannot tell if these upheavals are to be re- 
peated in future ages, but it seems more than 
probable. If not, then it is only a question of 
time — albeit an almost infinitely long time — when 
the surface of the earth will become of one uni- 
form level covered with a shallow ocean, and, in 
the polar regions, surmounted by caps of ever- 
lasting ice and snow. 
But the rain-drop is not the first cause of all 
the changes which we have noted. When resting 
in the ocean it is powerless. To perform its work 
it must be raised up and transferred to the hill- 
sides and mountain tops. Like all other forces on 
the earth, the force of the falling rain-drop and 
the rushing torrent has its source in the sun. The 
geologist can see in imagination the mountains 
and hills dwindling away and following the lower 
lands into the sea; but not a rain-drop can fall, 
not a brook flow down the hillside, or a river 
down its valley, except the water is first raised 
from the ocean by the same force that lights and 
warms our houses, that propels our railroad cars 
and steamships, that turns the wheels of all our 
machinery, and without which even life itself 
would be impossible. From the great central 
body of our system a constant stream of some 
mysterious manifestation of Nature is flowing to 
the earth; and the devastating force of the cy- 
clone, or the impercei)tible fall of a snow-flake or 
rain-drop, alike have their origin in that which, 
in our ignorance, we are obliged to term the radi- 
ant energy of the sun. 
A NOVEL LOCK. 
The curious lock illustrated in the engraving 
(from La Nature) is the invention of a young 
Norwegian farmer, M. Isaacsen, and is of more 
interest from the novel scientific principles in- 
volved in its construction than from its practical 
value. It consists of a bolt (B) which fastens the 
door, and is held in position by a weak spring (R). 
A pendulum (P) is suspended from a hook on the 
inside of the door, which, when set in motion, 
strikes an iron hammer (A), causing it to fall 
upon the head of the bolt and press it down so as 
to release it from the fastening of the door. A 
hole (C) is bored through the door opposite the 
bob of the pendulum, which is set in motion from 
the outside by blowing strongly through the hole. 
The details of this arrangement are shown in the 
upper corner of the engraving. 
The security of this lock depends upon the fact 
that several puff's of air are necessary to cause the 
pendulum to vibrate with a sufficient amplitude to 
reach the hammer, and each successive puff must 
be given at the exact moment when the pendulum 
passes the opening C on its journey towards the 
hammer ; otherwise one might blow all day with- 
out unlocking the door. The exact time of vibra- 
tion of the pendulum must thus be known to the 
person unlocking the door; and this is easily de- 
termined by a second pendulum, which he carries, 
consisting of a string to one end of which is at- 
tached a weight, and provided at the other end 
with a loop by which it can be conveniently at- 
tached to a hook on the outside of the door. This 
key pendulum is previously so adjusted as to 
l^4,li;lii.:,;'*ir^,i.'iM:M,|:.*'"r;.>jl^,.ll,l'!il c 
length that it vibrates in exactly the same period 
of time as the unlocking pendulum on the Inside 
of the door. If, then, it is desired to unlock the 
door, the key pendulum is hung on the outside 
and set in motion, and each alternate time that it 
passes its lowest point the operator blovi's strongly 
through the hole in the door, setting the unlock- 
ing pendulum into synchronous vibration, which, 
after a few puffs of air, strikes the hammer and 
releases the bolt. 
This lock is so simple in construction and so 
easily made that its duplication would be of great 
interest as a scientific experiment; and it might 
also serve a good purpose as a fastening for the 
door of a laboratory or other scientific "den." 
[Original In POPULAR SCIENCE NEWS.] 
STUDIES IN PLANT BIOLOGY. 
BY PROF. JAMES H. STOLLER. 
VI. 
THE APPLE-TREE. 
Our last study related to the Gymnosperms^ the 
first of the two great groups, or classes, of flower- 
ing plants. In the present study we have to deal 
with the second group, the Angiosperms, the high- 
est class of the plant kingdom. ' 
The Angiosperms include by far the greater 
number of the common plants of the fields and 
woods, and present an almost infinite variety in 
secondary features of form and structure. The 
majority are herbaceous and annual, the plant 
dying away after one season's existence ; others 
are woody shrubs, lasting a limited term of years ; 
and others are great trees of the forest— the larg- 
est and most enduring members of the vegetable 
kingdom. They are equally varied in habits ; a 
few are aerial, a large number are aquatics, most 
are terrestrials. The smallest member of the 
entire class is an aquatic, the tiny duck-weed 
(Lemna trisulca) of the ponds ; the largest mem- 
ber is Sequoia gigantea, the big tree of California, 
400 feet in height, and enduring hundreds of 
years. There are a few plants in the group 
which have acquired the parasitic habit, deriving 
nourishment from the living tissues of other 
plants to which they cling. The curious insec- 
tivorous plants are also included in this class. 
But all these various forms fall into a single natu- 
ral group by the fundamental similarity of their 
