186 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. [September 3,1870, 
the momentum of the carriage was stopped by fric¬ 
tion. We shall presently allude to the names of 
those distinguished men who have come prominently 
forward as the champions of a juster conception of 
tilings, but in the meantime let us consider some of 
those influences which served to prepare men’s minds 
for the reception of a truer hypothesis. 
We live in a world of work, of work from which 
we cannot possibly escape; and those of us who do 
not require to work in order to eat, must yet in some 
sense perform work in order to live. Gradually, and 
by very slow steps, the true nature of work came to 
be understood. It was seen, for instance, that it in¬ 
volved a much less expenditure of energy for a man 
to carry a pound weight along a level road than to 
carry it an equal distance up to the top of a moun¬ 
tain. 
It is not improbable that considerations of this 
kind may have led the way to a numerical estimate 
of work. 
Thus, if we raise a pound weight one foot high 
against the force of gravity we may call it one unit 
of work, in which case two pounds raised one foot 
high or one pound raised two feet high would repre¬ 
sent two units, and so on. We have therefore only 
to multiply the number of pounds by the vertical 
height in feet to which they are raised, and the pro¬ 
duct will represent the work done against gravity. 
The force of gravity, being very nearly constant at 
the earth’s surface and always in action, is a very 
convenient force for this purpose; but any other 
force, such as that of a spring, would do equally well 
to measure work by. Generalizing, we may say, the 
space moved over against a force multiplied into the 
intensity of that force will represent the quantity of 
work done. So much for the definition of work, and 
it is necessary to know what work is before proceed¬ 
ing to define Energy. 
Now what does the word Energy really mean? 
In the first place it does not mean force. 
Two substances may have an intense mutual at¬ 
traction, in virtue of which they form a very intimate 
union with one another; but when once this union 
has been consummated, although the force still con¬ 
tinues to exist, the combination is singularly defi¬ 
cient in Energy. Nor does Energy mean motion, 
for although we cannot have motion without Energy, 
yet we may have Energy without motion. 
By the word Energy is meant the power of doing 
work ; and the energy which a labouring man pos¬ 
sesses means, in the strictly physical sense, the num¬ 
ber of units of work which lie is capable of accom¬ 
plishing. 
This is a subject which at this stage we may at¬ 
tempt to illustrate by reference to a very different 
department of knowledge* 
The analogy which we shall venture to institute is 
between the social and the physical world, in the 
hope that those who are more familiar with the 
former than with the latter may be led to perceive 
clearly what is meant by the word Energy in a 
strictly physical sense. Energy in the social world 
is well understood. When a man pursues his course, 
undaunted by opposition and unappalled by obsta¬ 
cles, he. is said to be a very energetic man. 
By his energy is meant the power which he pos¬ 
* The subject has previously been discussed from this point 
of view by Messrs. Stewart and Lockyerfiin an article in 
Macmillan's Magazine , August, 1868. 
sesses of overcoming obstacles ; and the amount of 
this energy is measured (in the loose way in which 
we measure such tilings) by the amount of obstacles 
which he can overcome—the amoimt of work which 
he can do. Such a man may in truth be regarded 
as a social cannon-ball. By means of his energy of 
character he will scatter the ranks of his opponents 
and demolish their ramparts. Nevertheless, a man 
of this kind will sometimes be defeated by an oppo¬ 
nent who does not possess a tithe of his personal 
energy. Now, why is this ? A reply to this question 
will, if we do not mistake, exhibit in a striking man¬ 
ner the likeness that exists between the social and 
the physical world. The reason is that, although 
his opponent may be deficient in personal energy, yet 
he may possess more than an equivalent in the high 
position which he occupies, and it is simply this 
position that enables him to combat successfully with 
a man of much greater personal energy than himself. 
If two men throw stones at one another, one of whom 
stands at the top of a house and the other at the 
bottom, the man at the top of the house has evidently 
the advantage. 
So, in like manner, if two men of equal personal 
energy contend together, the one who has the highest 
social position has the best chance of succeeding. 
For tins high position means Energy under another 
form. It means that at some remote period a vast 
amount of personal energy was expended in raising 
the family into this high position. The founder of 
the family had, doubtless, greater Energy than most 
of his fellows, and spent it in raising himself and his 
family into a position of advantage. The personal 
element may have long since disappeared from the 
family, but not before it had been transmuted into 
something else, in virtue of which the present repre¬ 
sentative is able to accomplish a great deal, owing 
solely to the high position which he has acquired 
through the efforts of another. We thus see that in 
the social world we have what may justly be termed 
two kinds of Energy, namely:— 
1. Actual or personal Energy. 
2. Energy derived from position. 
Let us now again turn to the physical world. In 
this, as in the social world, it is difficult to ascend. 
The force of gravity may be compared to that force 
which keeps a man down in the world. If a stone 
be shot upwards with great velocity, it may be said 
to have in it a great deal of actual Energy, because 
it has the power of doing useful work or of overcom¬ 
ing up to a great height the obstacle interposed by 
gravity to its ascent, just as a man of great energy 
has the power of overcoming obstacles. But this 
stone as it continues to mount upwards will do so 
with a gradually decreasing velocity, until at the 
summit of its flight all the actual Energy with which 
it started will have been spent in raising it against 
the force of gravity to tins elevated position. It is 
now moving with no velocity—just, in fact, beginning 
to turn—and we may suppose it to be caught and 
lodged upon the top of a house. Here, then, it re¬ 
mains at rest, without the slightest tendency to mo¬ 
tion of any kind, and we are led to ask what has 
become of the Energy with which it began its flight ? 
Has this Energy disappeared from the universe with¬ 
out leaving behind it any equivalent ? Is it lost for 
ever, and utterly wasted ? But the answer to this 
question must be reserved for another article. 
(To he continued.) 
