NA TURE
I02
but rather, Why do they mo-c in orbits which be elHpses having the sun in one of the foci ? Hardly had this question been put, when a great genius answered it. The immortal Ne%vton told us that the same law which regulates the motions of the planets round the sun, and that of the moon round the earth, determines also the path of a stone thrown by the hand, or the velocity of an apple falling from a tree. One law was shown to hold throughout, and the expression of that law having been obtained, vi'e were easily led to the third stage in the development of astronomy. The problem was now from our knowledge of the present places and motions of the heavenly bodies, and of the laws which regulate these, to determine their future the planets
we know
?
to
—
In
places.
fact,
the last or prophetical stage of the science
had now been reached, and accordingly we had' a race of
who compiled our nautical almanacs, culminating two great prophets one French and one English who told us where to look for Neptune. Thus in the most'complete branch of physical inquiry We have, there have been three stages of development. first, the observational stage, the object of which was to discover the real motions of the planets of our system prophets
—
in
—
we have
the stage of generalisation, assigning the mechanical laws regulating these motions and, lastly, we have the stage of deduction, which, from a knowledge of next,
1869
_Nov. 25,
greater perhaps than there were in obtaining
the
true
motions of the heavenly bodies. It is not because, as in astronomy, our point of view but rather that we are so mixed is a movable one up with the earth and its atmosphere, and the motions of the latter are on so large a scale, that we find the greatest possible difficulty in grasping their true imWe are like a soldier in the midst of a great port. battle, who can give but a very poor and partial account of it, attaching, as he does, undue importance to those passages of arms with which he is most concerned, and ignorant, as he must be, of the general plan of the whole. What is wanted is a bird's-eye view of the atmosphere, such as it might appear to the inhabitants of the moon, who enjoy peculiar advantages in studying the physical features of our earth, just as we do with respect to the surface of our satellite. But there is another difficulty, at least Here the scientific worker is very in oceanic regions. much in the same position as the Jews of old when rebuilding their temple, that is to say, he must work with the one hand and fight with the other, especially when there is any great commotion going on. The commander of a vessel during a cyclone must first of all look after his vessel, and then, if he has any time to spare, it may be devoted to his barometer and thermometer. Indeed, whether on sea or land, the grand and interesting
much
the places and laws of motion of the heavenly bodies,
phenomena
predicts their future courses.
overwhelming, that the mind of the observer is not unThere is still a frequently unfitted for calm investigation.
Each
of these^ stages
encounter.
That
had
its
own
peculiar difficulty to
in ascertaining the actual
motions of the
heavenly bodies consisted in the fact that our point of view is a movable one, and it w-as only when this had been surmounted that the true explanation was obtained. Again, the difficulty in the generalisation accomplished by Newton consisted in recognising that the planets in their orbits arc subject to the same mechanical laws which regulate
motions on the earth's surface, and in ascertaining and applying these laws ; while, again, the difficulty in the third or deductive stage was an analytical one, for it was necessary to possess a to
calculate
the
method of
analysis sufficiently powerful
motions of a
set
of bodies mutually
attracting one another.
Now these historical facts, connected with the progress of astronomy, are of very great value to us, especially with reference to those other branches of science not so far advanced. We' h.ave, as it were, given us a standard of growth and development, and by measuring the younger child against the elder, we may be able to know the exact advancement of our latest born, and also the course of It discipline best calculated to ensure a vigorous growth. is by this astronomical standard that I now wish very briefly to measure what has been done in meteorology, and during these remarks I may perhaps venture to But here, suggest a course of diet and discipline. alas! there
stage
is
little
of progress
incomplete
advancement
—the
to chronicle:
observational
—
one
is
the yet
first
very
for, viewing meteorology as that science which treats of the physics of the earth's surface, and more particularly of the atmosphere its motion, and its physical properties, it must be acknowledged that these are very imperfectly known. At the same time it must be owned, that there are veiy serious difficulties in the way of obtaining this knowledge, more and
—
of nature
third difficulty,
cany
and that
is
in their train so
that
is
the great improbability (despite
the perseverance and industry shown by Glaisher and other meteorologists) of ever obtaining by observation a
very complete knowledge of the upper regions of the earth's atmosphere.
So much for the difficulties in the way of observing, and now one word with regard to the instrumental means at our disposal. Of late years these have been greatly improved, and one of the most notable achievements in this way is the anemometer of Dr. Robinson, by means of
which we can record continuously the horizontal velocity and direction of the wind. Another is the application of photography to meteorological observations, so successfully advocated and extended by the present distinguished President of the Royal Society, by means of which we obtain a continuous record of the pressure, temperature, and hygromctric condition of the air. Again, by means of certain electrical appliances due to Sir C.
others
we may
Wheatstone and
place our instnmient, whatever
it
be, at
the top of a mountain, or at the bottom of the sea, or in some equally inaccessible region, while the record of the
may be
read in the quiet and comThus, instrumentally we are. well equipped and rapidly improving, but the observations as yet made with complete instruments are very few indeed. come now to a very important point. Has the best I use been made of the observations already obtained . Of course we all know that there has been a deplorable want of co-operation among observers, as well as of system in making their observations but we may hope that, through the meteorological offices and societies instrument so placed fort of
own
our
studies.
established greater
There
in
all
civilised
amount of method is,
countries
of the world,
a
by degrees be obtained. however, something more than all this, and will
