des and difference of their angular velocities, is entirely lost. Wares. It would be highly important to obtain solutions on the supposition, that i differs from n or from 2n by a small quantity whose square may be neglected. Conclu BOD. sent (589.) Laplace's theory would be much more derata valuable if it were extended so far as to include the effects of friction. The methods of (315.), &c., would ry probably apply with sufficient accuracy. -901 nations (590.) The additions to the theory, indicated in the Tales. three last articles, would be exceedingly valuable, even if quite independent. If they could be treated in combination, their value would be very greatly increased. (591.) In the theory of waves, the most important point by far is the theory of river-tides, in which the of extent of vertical oscillation bears a sensible proportion to the depth; which we have partially treated in (192.), &c. The following extensions would very much increase its value; it is apprehended that they would introduce more of labour than of difficulty. -tides irable. of 200 of include (592.) The investigations of (218.) and (260.) must rible be extended so as to include the terms depending on the vertical oscillation, at least to the third order; observations showing that those terms are not only sensible but important. This investigation, if properly conducted, will include the extension of the investigation of (309.). nel. lade (593.) The effect of friction must be introduced in combination with these investigations. the (594.) The investigation must, if possible, be effected red for the case where the vertical oscillation is very great; as, for instance, where the low water leaves very small the depth on the bottom. In this case it is hopeless to very attempt a converging series, and an independent and finite method must be tried. Much would be gained if this could be effected in the simplest case, as for a rectangular channel, of uniform section, without friction. 25 as from the former. Much confusion would be removed Tides and (599.) It will probably also be found that the time Correction (595.) In regard to observations, it is very desirable (601.) The whole of the inequalities should then be Methods ob that simultaneous observations at short intervals should treated with reference to the theory of (451.), and so as for general be made on different points of some long tidal river, or to include the terms pointed out in (550.) and (554.). inequalities. some deep estuary, for examination of the change of For these it will not be sufficient to class together all the wave. These observations should be discussed as observations at which the declination was the same; esis mentioned in (479.). It is particularly desirable before this is done, the whole must be divided into two ble that these observations should be made in very high categories, namely, those of declinations increasing and spring tides and in very low neap tides, to discover of declinations diminishing, which are to be afterwards the laws of alteration of the various constants subdivided by absolute declinations. In like manner, depending on the range of the tide. as regards parallax, all the observations must be divided into the two categories of parallax increasing and parallax diminishing; which are to be afterwards sub divided by absolute parallax. The whole of these elements are to be taken for an epoch anterior by a quantity equal to the age of the tide. From the discussion of these inequalities in time as well as in height, the mass of the Moon is to be inferred by the process sketched in (555.); and the agreement of the different values of the mass will be the proof of agreement of theory and observation. (597.) In regard to the reduction of long series of tide-observations as applicable to particular ports, we shall only call the reader's attention to the following points. (598.) It will probably be found, from the inquiries, theoretical and experimental, to which we have alluded ed in above, that the elevation of high water in rivers or bays requires a certain multiplier to make its fluctuacb. tion of range comparable proportionably with the fluctuation of range on the coast, and that the depression of low water in like manner requires a multiplier different VOL. V. (602.) The best method of starting in these reductions cannot be the subject of general rule; the age of the tide however should be determined as early as possible. When the lunar parallax correction is ascertained, that part of it which applies uniformly in the same age of the Moon (depending on variation) should be subtracted from all the observations, or rather from the means of the groups, and then only can the semimenstrual inequality be found exactly. Each inequality, 3 F* Tides and when determined, should be subtracted from the observations before investigating a new one. Waves. Points to be noticed (603.) The same methods should be used for diurnal inequality, where it is conspicuous. But, as north declinations and south declinations are not now to be confounded, it will be advantageous to express the places of the Sun and Moon by north-polar-distances instead of declinations. (604.) In regard to the tracing of cotidal lines, the in the tide- principal defect, in marine localities which otherwise are well known, is in the Pacific Ocean generally. The attention of those who are interested in defining these lines should be particularly directed to the devising of observations in the Pacific Ocean. ARCHITECTURE. PART I. THE ANCIENT ARCHITECTURE OF GREECE, EGYPT, AND PERSIA. CHAPTER I. The Origin of Architecture. actice If we pass over the time when there existed no impleling ment capable of excavating a rock, or felling a tree, and with when the human savage, who drew his subsistence from it So- the Earth or waters, retired for the night to the shelter of some natural cave or hollow tree, we shall come to a period when the practice of building began in the World, and this was, probably, as early as the formation of the first Societies. As soon as a number of individuals or families had united themselves together for the purposes of defence, or of more effectually obtaining the means of support, habitations, larger and more commodious than those afforded by Nature, would be required. nd y the 3.ta The means resorted to by different Tribes of people to procure the necessary protection from the inclemency of the weather, may be reasonably supposed to vary according to the mode by which each people obtained its subsistence, to the materials for building which happened to be found in the places occupied, and, perhaps, to some peculiarities of character with which each people might be endowed. A pastoral nation, of which each family must change ere its place of abode as often as its flocks consume the productions of the Earth about the station it occupies, will have little inducement to erect permanent buildings; and, in a region nearly level, tents, or at most, light timber-huts, which can either be removed at pleasure, or abandoned without loss, will, probably, be the only dwellings it finds necessary to construct. Nearly the same thing may be said of a people inhabiting a mountainous country, or the sea-coast, and seeking its support from hunting or fishing; for the families or communities which pursue those modes of living, being thinly scattered over an extensive territory, will, in most cases, find it convenient to fix their abodes in caves formed by Nature or Art in the rocks. eir. But when men applied themselves to the cultivation ces of the ground, in a region where an ungrateful soil compelled them to the constant performance of a regular succession of labours in order to acquire the Art, means of subsistence, being necessarily attached to one spot, perhaps for life, it is conceivable that their dwellings would be of a permanent nature; and, consequently, it is among such a people that, through successive improvements, the practice of building may be expected to rise to the dignity of an Art. This would take place when, in process of time, men had learned to give to their buildings such internal arrangements as were suited to the purpose for which they were intended; to make the exterior forms characteristic of those purposes; and to YOL. V. 237 establish the fit proportions which the several parts of Part I. an edifice should bear to each other, in order to fulfil the above conditions, and to render the whole capable of producing an effect which might be pleasing to the eye. Now the Art of Architecture is a collection of rules for constructing buildings conformably to these principles. works un known. As this Art must have had its origin in some very The protosimple and rude construction, and as its early progress type of Armust have been made by insensible steps, neither the chitectural primitive form of a building nor the successive improvements it underwent were likely to excite such notice at the time they were made, as to cause the memory of them to be preserved. It is therefore hardly to be expected that any Tradition, still less that any Historical document should remain, concerning either the one or the other, of a date anterior to the establishment of a considerable number of general principles of construction. Afterwards, these becoming objects of study for persons who were called upon to exercise Architecture as a profession, would necessarily lead to an inquiry. whether they were founded upon any original model, and what that model might have been. first houses. Vitruvius, who wrote on the Art, in the time of Au- Probable gustus, or of one of his immediate successors, has, in form of the the Ist Chapter of his IId Book, indulged his own fancy, or recorded that of some more ancient Philosopher, respecting the origin of the Arts and Sciences, and particularly that of the Art of building. Having given a fabulous account of the origin of fire, he goes on to state that, by the comfort men derived from it, they were induced to form themselves into Societies, and erect buildings to shelter themselves from the severity of the climate. Such buildings, he thinks, would resemble the huts constructed by men who occupy the lowest grade in Society; and, to give an idea of that primitive style, he describes the mode of building practised by the Colchians, a people who probably were then in the same rude state as are now the inhabitants of the Islands in the South Seas. He says, it consisted in fixing trees upright in the ground, side by side, so as to include the space to be inhabited; the distance between the rows of trees equalling the length of the trees intended for the covering. The roof was laid over the tops of the upright trees, and above these, other upright trees were placed, in a manner similar to those below. Thus the building was raised to the height required. A roof was formed at the top, he says, by raising beams across from the four angles, so as to unite in a point; the sides and roof were filled up with boughs, and the interstices were stopped by chips and clay. It is, however, by no means necessary to suppose that the square or rectangular form which Vitruvius 21 |