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justed that the year should be longer or shorter than it actually is. We can imagine the earth'to revolve round the sun at a distance greater or less than that which it at present has, all the forces of the system remaining unaltered. If the earth were removed towards the centre by about one-eighth of its distance, the year would be diminished by about a month ; and in the same manner it would be increased by a month on increasing the distance by oneeighth. We can suppose the earth at a distance of 84 or 108 millions of miles, just as easily as at its present distance of 96 millions : we can suppose the earth, with its present stock of animals and vegetables, placed where Mars or where Venus is, and revolving in an orbit like one of theirs : on the former supposition, our year would become twenty-three, on the latter seren of our months. Or we can conceive the present distances of the parts of the system to continue what they are, and the size, or the density of the central mass, the sun, to be increased or diminished in any proportion ; and in this way the time of the earth’s revolution might have been increased or diminished in any degree; a greater velocity, and consequently a diminished period, being requisite, in order to balance an augmented central attraction. In any of these ways the length of the earth's natural year might have been different from what it now is : in the last way without any necessary alteration, so far as we can see, of temperature.” : Let us only irnagine the realization of any of these speculative changes which Mr. Whewell has suggested, and what would be the result? Why, the complete and instant extinction of the whole vegetable kingdom ; for the slightest attention to the growth of plants will satisfy the most casual observer, that the seasons, in their present order of succession, and in the exact amount of the interval of their duration, respectively, are indispensible to the various stages through which the fruits of the earth have to pass, before they attain maturity. Thus the cutting off of particular months of the year would take away the opportunity for many of our most useful plants for putting forth their leaves. The honessuckle protrudes them in the month of January; the gooseberry, currant, and elder in the end of February, or beginning of March; the willow, elm, and lime-tree in April ; the oak and ash, which are always the latest among trees, in the beginning or towards the middle of May. In the same manner the flowering has its regular time: the mezereon and snowdrop push forth their flowers in February; the primrose in the month of March; the cowslip in April; the great mass of plants in May and June; many in July, August, and September; some not till the month of October, as the meadow saffron; and some not till the approach and arrival of winter, as -the laurestinus and arbutus.
A most interesting chapter, in illustration of the adaptation of the influence of climate, (which is also a result belonging to the inorganic world), occurs under the head of geography of plants.
Mr. Whewell, in this investigation, traces in the variety of organized beings, an adaptation to the variety of climates, à provision for the support of man, and a means whereby civilization, and all its attendant advantages, are diffused. With Mr. Whewell we must be permitted to say, that we feel that there exists much ground for admiration in this vast variety of created things, in which we see such inexhaustible ingenuity displayed, in new forms, and in the constancy of the laws which apply to each of the divisions.
The constituents of climates are next considered in detail, and an admirable development of the laws of heat, as these apply to the earth, to the water, and to the air, is given in several succeeding chapters. The most wonderful feature in these descriptions is the series of modifications which these laws undergo, according to the nature of the medium to which they are directed, and the way in which ice is produced furnishes a remarkable example of the beautiful exactness of the change, as compared with the end for which it is designed. The general property of water is, to expand by heat, and contract by cold, the cold portions of the water generally occupying the lowest situation with respect to the warm parts. Continued cold will produce congelation, and therefore if the ordinary laws were left to go on, it would follow that the ice into which water was converted, would fall to the bottom, and there would accumulate until the whole of our lakes and seas would be turned into a solid mass, and then we should have no chance of water unless by the very irregular melting of the surfaces of the icy masses by the power of the summer's sun. How then are the usual laws sus. pended, and made to avoid such a dreadful result as must necessarily take place in case that no interference occurred? The following passage admirably answers the question :
It is obviated by a modification of the law which takes place when the temperature approaches this limit. Water contrac's by the increase of cold, till we come near the freezing temperature ; but then, by a further increase of cold, it contracts no more, but expands till the point at which it becomes it becomes ice. It contracts in cooling dowy to 40 degrees of Fahrenheit's thermometer; in cooling further it expands, and when cooled to 32 degrees, it freezes. Hence the greatest density of the fluid is at 40 degrees, and water of this temperature, or near it, will lie at the bottom with cooler water or with ice floating' above it. However much the surface be cooled, water colder than 40 cannot descend to displace water warmer than itself. Hence we can never have ice formed at the bottom of deep water. In approaching the freezing point, the coldest water will rise to the surface, and the congelation will take place there; and the ice so formed will remain at the surface, exposed to the warmth of the sun-beams and the air, and will uot survive any long continuance of such action.
Another peculiarity in the laws which regulate the action of cold on water is, that in the very act of freezing a further sudden and considerable expansion takes place. Many persons will have known instances of vessels
burst by the freezing of water in them. The consequence of this expansion is, that the specific gravity of ice is less than that of water of any temperature; and it therefore always floats in the unfrozen fluid. If this expansion of crystallization did not exist, ice would float in water which was below 40 degrees, but would sink when the fluid was above that tempera. ture: as the case is, it floats under all circumstances. The icy remnants of the effects of winter, which the river carries down its stream, are visible on its surface till they melt away: and the icebergs, which are detached from the shores of the polar seas, drift along, exposed to the sun and air, as well as to the water in which they are immersed.-pp. 83, 4.
In the remaining chapters upon the terrestrial adaptations, Mr. Whewell shows that a very large number of “ quantities” and laws seem to have been selected in the construction of the universe, and that from the adaptation of these mutually to each other springs the world such as we find it. Contemplating then, these laws and quantities which prevail in the inorganic world, we see that they compose a certain well defined number, and that in their operation they concur in innumerable points with other laws which belong to the organic system. Mr. Whewell observes, that the series of elements which are thus alluded to as forming the inorganic world, are each independent of the other, and so far as the mechanica! relations go, any of them might be altered without any material interference being the consequence. There are therefore, he concludes, a number of things in the structure of the world, which might have easily been different from what they are, but yet are arranged so exactly, as we find by our reasoning, that they ought to be, and thus we are brought to the conviction that it is not by chance, but by choice, that such contrivances exist. When we consider the laws themselves in their action—when we see steam expand at a very different rate from air, by the application of heatwhen we see water expand in freezing, and mercury contract—when we find heat passing through solids and fluids on altogether different principles, and that every substance has its own peculiar qualifications, and is therefore to be influenced differently by the same agents—when we consider all this, and the thousand similar phenomena with which creation abounds, shall we not feel how utterly impossible it is that such a world is a mere combination of atoms operating upon each other in conformity with some mysterious influence ?
In the second of his books, Mr. Whewell traces the manifestations of wise contrivance in what are called the cosmical arrangements of the planetary bodies, including the earth. The manner in which the planets move round the sun, and are held in space, involves a species of machinery of which we have no example in human mechanism, so that it is very difficult to find out a model familiar to the mind, which could be referred to as a useful illustration. Mr. Whewell has attempted to give an account of the adjustments which are observed in the arrangement of the solar
system, and as a right impression on this most interesting subject is a requisite of the first importance, we shall transcribe his very able and intelligible description :
If there be a wide shallow round basin of smooth marble, and if we take a smooth ball, as a billiard ball or a marble pellet, and throw it along the surface of the inside of the basin, the ball will generally make many revolutions round the inside of the bowl, gradually tending to the bottom in its motion. The gradual diminution of the motion, and consequent tendency of the ball to the bottom of the bowl, arises from the friction; and in order to make the motion correspond to that which takes place through the action of a central force, we must suppose this friction to be got rid of. In that case, the ball, once set a going, would run round the basin for ever, describing either a circle, or various kinds of ovals, according to the way in which it was originally thrown; whether quickly or slowly, and whether more or less obliquely along the surface.
Such a motion would be capable of the same kind of variety, and the same sort of adjustments, as the motion of a body revolving about a larger one by means of a central force. Perhaps the reader may understand what kind of adjustments these are, by supposing such a bowl and ball to be used for a game of skill. If the object of the players be to throw the pellet along the surface of the basin, so that after describing its curved path it shall pass through a small hole in a barrier at some distance from the starting point, it will easily be understood that some nicety in the regulation of the force and direction with which the ball is thrown will be necessary for success. In order to obtain a better image of the solar system, we must suppose the basin to be very large and the pellet very small. And it will easily be understood that as many pellets as there are planets might run round the bowl at the same time with different velocities. Such a contrivance might form a planetarium in which the mimic planets would be regulated by the laws of motion as the real planets are ; instead of being carried by wires and wheels, as is done in such machines of the common construction : and in this plenetarium the tendency of the planets to the sun is replaced by the tendency of the representative pellets to run down the slope of the bowl.-pp. 152, 3.
Mr. Whewell pursues the subject of cosmical arrangements in great detail, rendering familiar, and even amusing, some of the deepest mysteries of the highest branches of astonomy. One of the most striking conclusions, however, to which he calls our attention, after an elaborate survey of the system of the heavens, is the evidence which every thing connected with its arrangement gives, that the whole is destined for a finite duration. Geology had already pointed out, in the present condition of the earth, proofs that all its geological states have had their termination, and it is received as a certain principle amongst scientific men, that the astronomical conditions under which the revolutions of the earth are now going on, will of necessity cause, at some future time, a cessation of these revolutions, because of the existence of an influence which retards the celestial motions, and which, though
extremely slow in its operations, will ultimately change the length of our years, and at last put a stop to the motion of this earth round the sun. From this it will be seen how improper are our ordinary notions of the stability of visible things. When we compare, for instance, the ephemeral existence of man, as we daily do, with the eternal permanence, as we call it. of the sun, of the ocean, and the mountains, that have stood for thousands of years before us in the horizon, we little dream that in all those works of creation is inherent a principle of decay, which will inevitably effect their destruction. The forest trees droop and rot after the lapse of a few centuries, mountains crumble, or are made level by some convulsions from within, the sea even withdraws from its bed, and is driven about by the encroachments of land which falls from the continent, or is protruded from the bottom of the waters, and not only mountains and seas, but even the sun and moon themselves, are doomed to perish like man, the only difference being in the extent of the respite which is accorded to one in preference to the other. But the distance of time when the last of these effects is to take place is so inconceivable, its term, in fact, is not to be described by any expression of our language, that we cease to regard it with interest, and we may, with perfect satisfaction, dwell on the certainty of its continuing for a long course of centuries a habitation perfectly well adapted to living creatures. The remainder of this second book is taken up with a series of chapters on mechanical laws, in which those which belong to gravitation, motion, and friction are amply considered.
The third book presents us with a complete view of the inferences which arise from all the former views of the construction of the world, as respects the relation of man towards the Creator. Although there is no immediate connection between the material objects of the creation and the religious interests of man, yet a contemplation of the former enables us to decide upon some facts which are of the deepest importance to our eternal welfare. We cannot doubt, when we study carefully the laws which are in operation before us, that he who regulates all corporeal matters with such wisdom and such power, is the same supreme ruler who controls the conditions and actions of men. By going still farther, and tracing that wisdom and power as it is evinced in the arrangement of inorganic matter, in the creation of vegetables, of animals, and, lastly, of man, we must attribute to the author of all this, not merely transcendant capabilities, but, in the case of man, whom he endows with a regard for moral purity and probity, we find that the gift of such feelings is a sure proof that they are parts of the nature of the Divine Giver.
Amongst the features in the formation of the world which best attest to our comprehension the great attributes of the author of creation, we are particularly struck with the vast number of the objects which appear to be under the immediate protecting care of