2 
NATURAL HISTORY 
analysed in the several departments of General Physics. We ought, in treat- 
ing of Natural History, to employ precisely the same methods as in the Ge- 
neral Sciences ; and, therefore, we endeavour to adopt them, whenever the 
subjects under examination become sufficiently simple to permit that mode 
of investigation. But as this is seldom practicable, there arises, hence, an 
essential difference between the General Sciences and Natural History. 
For, in the former, the phenomena are examined under circumstances 
completely within the reach of the inquirer, who arrives, by anal3'sis, at 
general laws ; while, in the latter, they are removed, by unalterable con- 
ditions, beyond his control. In vain, he attempts to disengage them frohl 
the influence of general laws, already ascertained. He cannot reduce the 
problem to its elements, and, like the experimental philosopher, withdi'aw 
successively each condition ; but he must reason upon all its conditions 
at once, and only arrive, by conjecture, at the probable result of such an 
analysis. Let him seek to ascertain, by direct experiment, any one of 
the numerous phenomena essential to the life of an animal, though but 
slightly elevated in the scale of being, 
“ And ere he touch the vital spark — ’tis fled.” 
Thus, it appears that, while Mechanics has become a science chiefly of 
CALCULATION, and Chemistry of experiment. Natural History will long re- 
main, in most of its departments, a science wholly of observation. 
The latter part of this remark must, however, he restricted to the early stages of 
Natural History ; because, in its more matured condition, it becomes a science of 
demonstration. Every branch of physics has one leading object in view, and that is, 
the discovery of the ultimate laws of Nature. Philosophy regards this as of primary 
importance ; while utility is held only as of secondary rank. Science, in its most 
comprehensive sense, is a superstructure founded on facts, or acquired by oxperionco ; 
and hence, in its early stages, wo consider it as entirely limited to observation : but 
when we have learned to generalize, and find that truths agree in their several relations, 
we have arrived at the demonstrative part of the science. It is not, therefore, from 
a mere knowledge of correct nomenclature, or from a capacity to recognize at sight a 
natural object, that we arc entitled to apply the name of scientijic knowledge to Na- 
tural History; but only when we have succeeded, by observation, in deducing the laws 
which regulate these objects, in their relatioms to surrounding beings. 
These three terms, Calculation, Observation, and Experiment, express, 
with sufficient accuracj', the manner of cultivating the several branches 
of Physical Science ; but, by exhibiting among them very different degrees 
of certainty, they indicate, at the same time, the ultimate point to which 
Chemistry and Natural History ought to tend, in order to rise nearer to 
perfection. Calculation, in a manner, sways Nature; it determines the 
phenomena more exactly than can be done by observation alone: Expe- 
riment obliges Nature to unveil: Observation watches when she is refrac- 
tory, and seeks to surprise her. 
Natural History employs with advantage, on many occasions, a principle 
of reasoning peculiar to itself, termed the conditiojis of eiisiencc, or, more 
commonly, final caiues. zVs nothing can exist except it contains within 
itself all the conditions which render e.xistence possible, it is evident, that 
there ought to be such a mutiud adaptation of the various parts of each 
being among themselves, and such ;in accommodation of their structure 
to the circumstances of surrounding beings, as to render possible the ex- 
istence of the whole. The analysis of these conditions often leads to the 
discovery of general laws, with a clearness of demonstration, surpassed 
only by the evidence of direct experiment or calculation. 
It was by the knowledge of this principle, that the celebrated Dr William Harvey 
was enabled to discover the circulation of the blood in Man. The Honourahlo Robert 
Boyle relates his conversation with Ijr Harvey on this subject, in the following words : 
— “ I remember, that when I asked our famous Harvey, in the only discourse I 
had with him (which was but a little while before he died,) what were the things 
which induced him to think of a Circulation of the blood? he answered mo, that when 
he took notice that the valves in the veins of so many parts of tho body were so 
placeil, that they gave free passage to the blood towards the heart, but opposed tho 
passage of the venal blood the contrary way, ho was invited to think, that so provident 
a c.-.use as Nature had not placed so many valves without design : and no design seemed 
more probable than that, since the blood could not well (because of the intei-posing 
valves,) bo sent by the veins to the limbs, it should bo sent through the arteries and 
return through tho veins, whose valves did not oppose its course that way.” It is 
evident from this, and many other similar instances, that, in ozamining the subjects of 
Natural History, wo shall best advance the science, by considering attentively the uses 
and ends designed by Nature in their fommtion, and the functions which their organs 
arc destined to perform. This manner of investigation has been objected to by some 
philosophers, among whom is Des Cai tos, as being a presumptuous attempt on the 
part of human reason, far above its powers, to penetrate into the secret designs of tho 
Creator. The following passage, extracted from the works of Mr Boyla above quoted, 
forms a satisfactory answer to this objection : — “ Suppose that a countryman, being in 
a clear day brought into the garden of some famous niathematici.'m, should see there 
one of the muious gnomonic instruments, that show at once tho place of the sun in 
the zodiac, his declination from the equator, the day of tho month, tho length of the 
day, &o. &c., it would indeed be presumptuous in him, being unacquainted both with 
tho mathematical disciplines, and the several intentions of the artist, to pretend or think 
himself able to discover all the ends for which so curious and elaborate a piece was 
framed : but when he sees it furnished with a style, with horary lines and numbers, 
and, in short, with all the requisites of a sim-dial, and manifestly perceives tho sha- 
dow to mark from time to time the hour of the d.ay, it would be no more a presump- 
tion than an error in him to conclude, that (whatever other uses the instrument was fit 
or was designed for,) it is a sun-dial, and was meant to show the hour of the day.” 
The whole science of Natural History teems with instances, showing the successful 
application of the general principle called the conditions of existence. Thus, when we 
sec an animal, possessed of a capacious stomach, long intestines, and a massive struc- 
ture, wo may safely infer th.at it is herbivorous, or feeding on vegetables, slow in its 
movemohts, and of timid and gentle habits. On the contrary, when wo find .an 
animal with short intestines, straight stomach, and .armed with weapons of offence, we 
immediately conclude it to be carnivorous, or feeding upon flesh, and of a fierce and 
active disposition. 
It is further observed by the author, in his Lectures on Comparative Anatomy, that 
the construction of the alimentary canal determines, in a manner perfectly absolute, the 
kind of food on which the animal is nourished. For, if the animal did not possess, in 
its senses and organs of motion, the means of distinguishing the- kinds of aliment suited 
to its nature, it is obvious that it could not exist. An animal, therefore, which can 
only digest flesh, must, to preserve its species, Imvcthc power of discovering its prey, 
of pursuing, of seizing, of overcoming, and of tearing it in pieces. It is necessary, 
then, that tho animal should have a penefratuig eye, a quick smell, a swift mo- 
tion, adilress ajid strength in tho jaws and talons. Agreeably to this necessity, a 
sharp tooth, fitted for cutting flesh, is never co-exlstcnt in the same species with a 
hoof covered with horn, which can only support tho animal, hut cannot grasp any 
thing : hence the law, according to which all hoofed animals are herbivorous, and also 
those still more detailed laws, which are hut corollaries to the first, that hoofs indicate 
molar teeth or grinders with flat crowns, a very long alimentary canal, with a ca- 
pacious and multiplied stomach. 
It is only after having exhausted all the laws of general physics, and 
the conditions of existence, that we are compelled to resort to the simple 
laws of observation. The most eflectual mode of deducing these is by 
comparison; by observing the same body successively in the various po- 
sitions in which it is placed bj' Nature; and by comparing dificrent bodies 
with each other, until wo obtain a knowledge of some constant relation.s 
between their structure and tlie phenomena exliibited by them. These 
various bodies thus form a species of experiments, performed entirely by 
Nature’s hand, where diflerent parts of cacli are supplied or abstracted, 
as we would desire to treat tliem in our laboratories; and the results of 
these additions or abstractions arc presented to us spontaneously. We 
are thus enabled to deduce the invariable laws influencing these relations, 
and to apply them in a manner, similar to the laws determined by general 
physics. Could we but incorporate these laws of observation with the 
general laws of physics, either directly or by means of the principle called 
the conffitions of existence, the system of natural science would be com- 
plete, and the mutual influence of all beings would he perceived through- 
out the whole. To approach this great end the eflbrts of naturalists should 
be steadily directed. 
All researches of this kind presuppose that we have the means of dis- 
tinguishing witli certainty, and of describing to others with accuracy, 
the objects under investigation; otherwise, we shall be continually liable 
to fall into confusion, amidst the innumerable beings which surround us. 
Natural History ought, therefore, to have for its basis, what has been tech- 
nically termed a system of nature, or a methodical and extensive catalogue, 
arranged with divisions and subdivisions, in whicli all beings shall bear 
suitable names and distinct characters* That we may always be able to 
discover the cliiiracter of any particular being from knowing its name, or 
the name from knowing its specific character, wo must found this peculiar 
description upon some essential or permanent properties of the being. We 
must not derive the character from habits, or colour alone, as these projter- 
ties are ever liable to be modified by external circumstances, but froni 
internal organization or coMrosmoN. 
MTicn Natural History was in its infancy, the objects were few and easily reineni- 
bered. Systems of classification were eitiier neglected as unnecessary, or confined 
only to those general tbvislons and subdivisions, which it was impossible to overlook. 
But ever since the chiys of Aristotle, A.C. 330, when Alexander the Great iiad in- 
creased the number of known species of animals by some of the productions of the 
conquered East, tho necessity of a precise system of classification has been univer- 
sally admitted; and now, the progress of geographical knowledge has enlarged the 
bounds of the science to so vast an extent, and disclosed a variety so inconceivable 
of forms hitiiertu unknown, that the naturalist would, without classification, he over- 
whelmed with endless details. Yet tho different kinds of animals are daily becoming 
more numerous by the contributions of enlightened travellers. In 17S0, the number 
of distinct species of insects was estimated at 20,000, and now it cannot be Ics:* 
than 100,000. And when it is considered how small a part of tho globe has been 
• The word character, in Natural History, denotes that iwcullar description of an 
object which distinguishes it from all others. Tims wo say, tho character of t«“'* 
is, “ Teeth of throe kinds, posterior extremities furnished with feet anterior with 
himds, &c. &c.” — Translator. ‘ 
