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disappointed in finding no such development, a plain reasoner would not: be so disappointed : for is it not obvious that avarice, or shame, or jea. lousy, might in a moment operate so powerfully as to lead an individual to the crime of murder, whose nature and habits were as far as possible removed from the propensity to that crime ; and who, consequently, according to Dr. Gall's own principles, would be devoid of any undue development of the organ of murder ?
With respect to ourselves, indeed, the study of the system may be attended sometimes with the happiest consequences : for if, from the contemplation of it, we can be strengthened in our conviction of the fact, which both reason and revelation teach us, that each individual is liable to particular temptations depending on his specific temperament, we shall thus have one additional memento of our frailty, one additional incentive to watch over and combat “ the sin which doth so easily beset us."pp. 64–66.
After this anatomical view of the structure and functions of the brain in man, Dr. Kidd proceeds to give a cursory view of the extent of human power over the objects of the external world. It is unfortunately on this great and important subject that the author has altogether lost sight of materials which are perhaps the best calculated of any that can be found throughout the whole of the branches of this investigation, to manifest the power, the wisdom, and the benificence of the Creator. Although Dr. Kidd formally makes his progress over the several kingdoms of nature, yet he seems to us very unhappy in the choice which he has made of the immediate materials for his illustrations. But the uses of the atmo. sphere, and of water, in contributing to the wants and convenience of man, are ingeniously displayed, and the explanations of their applicability, on various important occasions, will be found not only interesting but highly valuable. In dismissing the particular subject of atmospherical air, Dr. Kidd calls our attention to the multiplicity of beneficial effects, each differing in their character, which result from the same agent, and often too at the same moment. Thus, he says, while we have seen the air of the atmosphere serving as the reservoir of that mass of water from whence clouds of rain, and consequently springs and rivers are derived, we have also seen that it at the same time prevents, by the effect of its pressure on their surface, the unlimited evaporation and consequent exhaustion of the ocean, and other sources, from whence that mass of water is supplied. And again, while the agitation of the air contributes to the health of man, by supplying those currents which remove or prevent the accumulation of local impurities, it at the same time facilitates that intercourse between different nations in which the welfare of the whole world is ultimately concerned. And, lastly, while in passing from the lungs in the act of expiration it essentially forms the voice, it at the same time removes from the system that noxious principle, the retention of which would be incompatible with life.
The chapters on the adaptation of the mineral kingdom to the uses of man are full of interest and instruction. This being a favourite subject, and one that is associated with his early recollections, the author dwells upon it with all the enthusiasm which in his youth he was accustomed to bring to the study of the subject. Under this distinct head, Dr. Kidd considers the application of mineral substances to architecture and sculpture-next he traces their use as gems and precious stones, and proceeds to the geological formation of the crust of the earth, as it may be made to yield materials for the necessities, comforts, and conveniences of man. The
the work, are those on the metals, and on common salt. We present the reader with two very fair specimens of the popular yet truly scientific method with which Dr. Kidd treats subjects that are usually deemed incapable of a familiar explanation :
What an anomaly does it (quicksilver) not present in the general history of metals ; existing, under all common variations of temperature, in a fluid state, while all other metals, with which we are familiar, are, under the same variations, solid ; nor indeed are they capable of becoming fluid, but by an elevation of temperature to which they are hardly liable to be exposed, unless designedly: lastly, in consequence of its fluidity, destitute of malleability and ductility; which are among the most valuable properties of the metals taken collectively? . This state of fuidity, however, is
for hence it is successfully employed for many purposes, to which, were it solid, it would be inapplicable. How valuable is its use in the construction of the common thermometer and barometer; the value, in the case of the former instrument, depending entirely on its fluidity, and on the physical characters of the fluid itself-the equable ratio, for instance, of its contraction and expansion under widely varying degrees of temperature, and its property of remaining fluid through a greater range of temperature than any other known substance. And, in the case of the barometer, what fluid is there which could supply the place of quicksilver, with any degree of convenience ? since, from the great specific gravity of this metal, a column of the perpendicular height of about thirty inches, sufficiently answers the intended purpose ; which column in the case of almost every other fluid, would amount to as many feet. And as, in such a case, the column must necessarily be contained in a glass tube, in order to make the alterations in its height visible, how would it be possible to render such an instrument portable ? and yet, if not portable, it would often be of no use when most wanted.--pp. 97, 98.
Of common salt, Dr. Kidd gives us the following account:
· It does not appear that the mineral kingdom contains a single species capable of being employed as food : but there is one mineral species, which indirectly contributes to the nourishment of many other animals as well as man, and that is common salt; the flavour of which, to a certain extent, is not only grateful to the palate, but, practically speaking, mankind could
not exist, or at least never have existed, without the constant use of it. Thus, though employed in very small quantities at a time by any individual, and almost exclusively for the purpose either of preserving or of rendering his food more palatable, this substance may fairly be classed among the principal necessaries of life : and, correspondently with this statement, we find that nature has supplied it in abundance, indeed in profusion often, in various parts of the globe : for, to say nothing of those apparently inex. haustible masses which occur ancong the solid strata of the earth, and which have been constantly quarried through successive ,ages from the earliest records of history, the ocean itself is a never-failing source of this valuable substance. In other instances salt springs afford the means of a ready supply; and throughout a considerable part of the sandy districts of Africa and Asia, the soil itself abounds with it. The abundant supply of common salt coincides with its extensive utility. It is every where indispensible to the comforts of man; and it is every where found, or easily obtained by him. And, though not to the same extent, the same observation holds with reference to many other natural saline compounds. Thus carbonate of potash, and natron or carbonate of soda, alum, borax, sal ammoniac, and sulphate of iron, or green vitriol, which are most extensively useful salts in many processes of the arts, are either found abundantly in various parts of the world, or may be obtained by very easy means : while a thousand other saline compounds, which are rarely of any practical importance, are scarcely known to exist in a native state. - pp. 199-201.
The next subject considered in this volume is the adaptation of the substances of the vegetable kingdom to the immediate or indirect service of man. The author first speaks of the cocoa nut tree, which offers in its physiological history a beautiful example of the important ends which nature effects by means the most simple. Dr. Kidd then shows how this plant is propagated spontaneously in the coral islands; he next enters upon the description of the formation of those islands themselves, which, whilst they appear to be built up by chance, and completed in their structure by mere accident, yet advance with a degree of regularity that is not surpassed by the uniform order even of the planetary system itself.
Vegetables, as a source of food, form the subject of much too brief and imperfect a chapter in this volume. Dr. Kidd appears to think, that he has sufficiently proved the adaptation of vegetables to the service of man when he shows, that as food, as medicine, as supplying materials for clothing, for instruments in the arts, &c., they perform an important part in the general economy of nature. But however strongly we may be impressed by the contemplation of such adaptations as these, yet they fall far short of another series of adaptations, whereby the vegetable kingdom is made subservient to the purposes of man. As Dr. Kidd has not even alluded to this topic, we are at liberty to dwell on it for a short time.
The individuals of the vegetable world appear to be endowed with a tendency to change their nature, and this tendency has been
80 well manifested by the spontaneous operations of nature herself, that man's ingenuity has been summoned to a pursuit in which the triumphs of intelligence know no bounds. In short, the principle on which the vegetable kingdom seems to have been founded, was, that it should be susceptible of great modifications under the controlling influence of man, and that according as he exercised his mind in studying nature, so would he be repaid by a vast superiority in the use and value of the plant which had been subjected to his skill. Hence we see the mightiest revolutions take place in the characters and virtues of particular plants ; hence was it that the savage sloe was tamed down, as it were, by human art, into the sweet and nutritious green gage plum. The whole of the processes employed by gardeners for increasing the quality of the fruit, or indeed for effecting any change in an individual plant for the better, are the result of a knowledge of certain laws that seem to have been specifically applied to the vegetable kingdom for the purpose of inciting man to the task of improving his lot, and of increasing his own happiness, We have said that a tendency to change their nature has been found to exist in the members of the vegetable kingdom, and we shall add, that this peculiar attribute appears to be left wholly to the capricious disposal of man; for supposing that we wish to interfere with some of the most delicate of nature's processes in the propagation of plants, we shall find that it is in our power to do so, not only without detriment, but with signal advantage, both as to quality and quantity. This astonishing power possessed by man, enables him to intermix the pollen and stigma of two varieties, in order that an intermediate one, superior to both, may be produced ; so that there is no kind of fruit that grows which may not be ameliorated by the art of man. All the operations for ringing bark, bending down branches, training, &c., together with laying, budding, grafting, striking from cuttings, &c.,-all these methods of raising the vegetable kingdom in the scale of utility to the animal creation, must be regarded as so many evidences of the design of Providence, that he has left the control of the vegetable world to man, and has fixed a bounty on the success with which his industry and intelligence may enable man to avail himself of this power. Here then we have a most important theme for contemplation, in which we can trace definite contrivances ordained by the Creator, by which vegetables are peculiarly adapted to the physical condition of man: we regret that the deeply interesting topic was overlooked by Dr. Kidd, as its investigation forms so necessary a portion of his task, and at the same time would have contributed so valuable a share to its proper performance. It may be argued, that the department of vegetable physiology has already devolved upon a colleague of Dr. Kidd's, and that for him to pursue the subject which has just been alluded to, might be justly deemed an invasion of a province which was already appropriated to another. But there is no foundation for such an excuse, because the science of physiology, 'as respects vegetables, inquires only into the laws which govern their existence, whilst the study of the connection subsisting between these laws and man, belongs naturally to him who has to explain the adaptation of external nature to man's physical condition.
Yet, whilst we mark our regret that so substantial an omission should have been found in this work, we are by no means disposed to undervalue the merit of the descriptions which it contains, with reference to the vegetable kingdom. In speaking of the diversified qualities of different vegetable productions, Dr. Kidd remarks how well the rigid fibre and compact texture of the oak enable the triumphant bark to ride securely on the ocean ; whilst the flexibility of hemp and flax renders them capable of being woven and formed into sails and cordage. The manner, too, is very happy in which he describes the policy of Providence in meeting the wants of mankind, and in adjusting the supply of vegetable nourishment to the nature of their local situation. Thus wheat, he says, which contains a more strengthening principle of nutrition than the product of the palms and arrow-root, and is therefore better calculated to support the hardier efforts of the inhabitants of temperate or cold climates, will not grow readily in inter-tropical climates; and, reciprocally, the palms and cognate plants of inter-tropical regions cease to be productive, if cultivated much beyond the tropics. And the orange, the lemon, the water-melon, the grape, and the fig, which are easily cultivated in warm climates, by the abundance of their juice, are enabled both to allay the sensation of present heat and thirst, and to repair the loss of that natural moisture of the body which is continually passing from it in the form of either sensible or insensible perspiration. Even in the temperate climate of our own island, how many days are there, during the summer, in which such fruits are most refreshing: and to gratify the desire of that refreshment, we import such species as are capable of bearing a long voyage ; among which the orange is a very principal article of import: nor would it be easy to calculate the myriads of that fruit which are annually consumed in this country. But the cognate fruit, the lemon, at the same time that, on account of the grateful and aromatic flavour of its juice, it is occasionally as eagerly sought as the orange, serves a still higher purpose : for the acid contained in it has been successfully employed, as an antidote and a remedy for one of the most dreadful diseases to which mariners are subject. Sea-scurvy, in fact, has all but disappeared since the adoption of this remedy.
By a natural transition, Dr. Kidd proceeds to the subject of the adaptation of animals to the physical condition of man. In the animal kingdom we have proofs still more striking of the exercise of a cautious and a provident care, particularly in the distribution of animals, it being uniformly the law that each particular series is located in those districts where there is food and a climate suited