of winds, which had enabled Admiral Fitzroy to forecast approaching storms and save the lives of seamen, the president referred to the boundless inquiries comprehended under the term Physical Geography-inquiries which involve not only the geographical distribution of man, animals, and plants, but also the conditions and relations of the ocean and the atmosphere to the earth. The wandering habits of our countrymen are constantly augmenting our knowledge of foreign lands; and, as the Chancellor of the Exchequer, on recently addressing geographers, most truly remarked, the love of adventure, the boldness in facing danger, the strong self-reliance, the ready presence of mind, which lie at the root of the greatness of this country, are also the foundation of the achievements of our geographical explorers.

A brief résumé may now be given of the papers of most general interest in this department of science. A paper on the Delta of the Amazons, by Mr. H. W. Bates, who went to South America as a naturalist, and collected eight thousand new plants during his residence there of eleven years, was a valuable communication, and remarkable for applying the results of the comparison of the fauna and flora of one country with those of an adjoining country to the elucidation of problems respecting the former configuration of lands. The result appears to be, that where there is a well-defined endemic fauna and flora, the land containing them is of great antiquity. The same mode of argument has been employed to show that Great Britain was formerly connected with the continent of Europe, for scarcely a species of animal or plant is found in Great Britain which does not exist on the neighbouring mainland.

In his paper on the Volcanic Phenomena of Nicaragua, Captain Pim described the three great volcanoes of that isthmus which is directly in the line of igneous action that traverses the continents of North and South America. One of these volcanoes (Masaya), after a century of activity, during which an inundation of lava reached to a distance of fifteen miles, became quiescent in 1760. The most recent eruption in Nicaragua (1835) was from the volcano Coseguina; ashes from it fell within a radius of a thousand miles, and pumice fell a hundred miles at

sea.

Cattle now, however, graze in the crater. The summit of the third of these volcanoes is constantly wreathed with smoke. At the foot there is a fountain of boiling water. A circular cavity a quarter of a mile in diameter, now filled with water, and called the lake of Tiscapa, is surrounded by almost perpendicular cliffs. This, and some similar lakes with precipitous sides, and which have no visible outlet, seem to be the craters of volcanoes no longer active. The chemical composition of the water is dissimilar in all these lakes-a circumstance of some interest to the investigator of mineral and thermal springs. This portion of the continent is thought to have occupied at some former period a higher level than it does at present.

Viscount Milton and Dr. Cheadle described their expedition across the Rocky Mountains. The country from the Red River settlement to their base is described as a tract of rich pasture and woodland, intersected by rivers, on the banks of which there are beds of ironstone and coal, and enjoying a Canadian climate. It is nevertheless, from its isolated position, left utterly desolate, but if communication could be established with Canada and British Columbia, it would become a valuable possession to

Great Britain. The noble young traveller and his enterprising companion seem to have encountered most harassing fatigues and perils: a day's journey generally consisted of continual floundering through bogs or plunging amongst fallen timber, and sometimes, for as far as from London to York, the track lay through unbroken forest or by narrow ledges on the face of precipitous cliffs, above streams and lakes, and through narrow gorges shut in by inaccessible heights. The route, however, is described as presenting no serious obstacles to an engineer, and as one which would afford direct communication between Canada and the gold regions of British Columbia, and which passes through British territory and amongst Indians who are peaceable and friendly. The Rocky Mountains appear to separate rich and productive land from the sandy soil of British Columbia, which is rich only in its minerals. In the debate upon this paper, it was very interesting to hear Sir John Richardson, the companion of Franklin, relate what he had first learned about the country fifty years ago. To the geologist, the paper afforded much that was interesting, especially in describing certain parallel roads and terraces which, from the drawings exhibited, appear to resemble the famous "parallel roads" of Glenroy, and are probably the remains of former lakes in what is now the valley of the Fraser River.

But it was to Africa that the attention of the Bath meeting was chiefly directed, and the largest and most enthusiastic of the evening gatherings assembled to hear Dr. Livingstone's account of his ascent of the Zambesi River. His explorations, however, have not afforded any results interesting to the geologist, save the statement that the elevated plateau which forms the interior of the continent is probably the oldest land in the world. The adventurous traveller described his progress in a miserable little steamer, which the crocodiles mistook for some land animal swimming, and rushed at it in the expectation of a feast. The audience who flocked to the lecture did not appear to share the disappointment of the crocodiles, but the result did not seem commensurate with the expectations raised. He explored the Shiré, which is not known to have been previously explored by any European, and saw in the marshes eight hundred elephants at one time. In many of the villages on the route iron is smelted by the natives from the ore. They live in fear of witchcraft, and, when persons are accused, they drink what is called the ordeal water. They cultivate grain and decoct beer, on the strength of which all the inhabitants of a village will sometimes become tipsy together. He did not say whether the potentates of these places, like the sable dignitaries of some other parts of Africa, regard a cast-off full-dress livery of the lord mayor's footman as the summit of human splendour, but they have very loose notions as to property, and he described the Makololo as inveterate cattle-lifters. The chief points of geographical interest in Dr. Livingstone's lecture were the following: The explorers discovered Lake Shirwa, and found the mountains on the east of it to rise to a height of from eight thousand to nine thousand feet. They found the Shiré to fall into Lake Nyassa about sixty miles above the cataracts, and the country to rise into elevated plateaux, cool and well watered. Dr. Livingstone endeavoured to persuade the people to cultivate cotton for exportation, and he asserts that the district affords one of the finest cotton-fields in the world-the slave trade, however, which flourishes on the east coast under the Portuguese, is the gigantic

evil which meets the civiliser everywhere. Lake Nyassa is described as a fine fresh-water lake of great depth; the explorers saw it for two hundred and twenty-five miles of its length, and describe it as being from fifty to sixty miles wide. The heights which rise around it proved to be the edges of a great plateau three thousand feet above the sea-an elevated land on which European settlers might enjoy life and comfort, and to which the rivers afford a highway.

One of the most interesting problems of ethnology was the subject of Mr. Stuart Poole's paper on "Ethnic Relations of the Egyptian Race." The increase of Arab settlements in Egypt since the Arab conquest, has made the Egyptians much more Arab than they were, yet the Nigritian characteristics of type are not obliterated in Egypt. If four thousand years, argues Mr. Poole, is a mere point in the change from Negro to Arab, no conception can be formed of the vast period of time required for the transformation of the race. If the Egyptian, Negro, and Arab varieties of man have remained unchanged for three thousand years, we can only suppose that they had an independent origin. The ancient Egyptian monuments show us Egypt inhabited by the Egyptians only, and Mr. Poole thinks they exhibit traces of a double ancestry. On the east frontier were Arabs, yellow in complexion, with red beards, and blue or grey eyes-the red men. On the west frontier were other Arab tribes, white in complexion. All the southern tribes are represented as Negroes. He regards the valley of the Nile as having been anciently occupied by Negro tribes, with whom eastern colonists intermixed; and comparing the old Egyptian race with its neighbours, he thinks the union of Nigritian and Semitic features may be traced, and also a blending in the religion, art, and language of the ancient Egyptians. In the discussion on this paper, Sir Henry Rawlinson, though recognising the doctrine of permanency of type, contended that climate might produce change in colour.

But, to glance from the historic monuments of Egypt to the ruder traces of pre-historic man in Europe. The president had remarked in his "inaugural" address, that archæologists are satisfied that, in central Europe, the age of bronze weapons, to which age the Swiss lakedwellings belong, preceded the Roman invasion of Switzerland, but had been preceded by the age in which only stone weapons were fabricated, and to which the Danish "kitchen-middens" seem assignable. "But of higher antiquity," said Sir Charles, "was the age of those ruder implements of stone which are buried in the fluviatile drift of Amiens and Abbeville, and are mingled in the same gravel with the bones of extinct quadrupeds.” This remark is applicable to the drift not only in those localities, but in other countries; for, ex. gr., fossil teeth of the African elephant have been recently found near Madrid in old valley drift containing flint implements of the same antique type. Indeed, we have now evidence that man co-existed in Europe with three species of elephant, of which two, viz. the mammoth and the Elephas antiquus, are extinct, and the third survives only in Africa. Since the era of the flint implements-of those early vestiges of our race-geographical conditions have been changed, and many species of animals have disappeared.

Mr. Crawfurd, in a paper on "The supposed Stone, Bronze, and Iron Ages of Society," conceded that as far as relates to the early inhabitants of Denmark and those who constructed the pile villages of Swiss lakes,

three different ages of civilisation are marked by the use of arms and implements respectively of stone, of bronze, and of iron; but he contended that the order of progress thus indicated is not applicable to all mankind, and that the first implements of man were of wood or bone; that the stone period constituted the second age; and that in the third, metals were substituted for stone. "Metallurgical considerations," said Mr. Crawfurd, "indicate that iron was the metal first used," but in some cases -for instance, in ancient Egypt-a bronze age preceded an iron age. From the ancient civilisation of India, it seems probable that the art of reducing the ores of iron to a metallic state was there first invented, and that bronze followed iron among the Hindus. Bronze, however, was known to the rude people who dwelt on the Swiss lakes and on the shores of Denmark, and there is no trace that iron was known to them, but their weapons and implements of bronze must, he contended, have been derived from a people more advanced than themselves-probably from the Etruscans or other inhabitants of Northern Italy. From the small size of the hilts of the bronze swords found in the shell-heaps and peat of Scandinavia, it may be inferred that they were derived from an Asiatic people-probably, in the opinion of Mr. Crawfurd, the same who introduced the Runic characters into Scandinavia. Professor Rawlinson, who agreed in the main with Mr. Crawfurd's views, remarked that among the ruins of Babylon no iron implements had been found. Before passing from subjects connected with the antiquity of man, it may be mentioned that one of the remarkable mounds of La Tinière, on the Lake of Geneva, near Villeneuve, has been recently cut through by the railway, and from the aspect of the beds exposed in the section, Mons. Morlot has inferred that at three successive epochs the action of the torrent spread the reliquiæ of human occupation over the growing delta of La Tinière, and the bed in which the earliest trace of man appears is computed by him to be more than six thousand years old. There is a greater conical mound, apparently deposited at a time when the lake stood at a higher level, and of this the age is computed at a thousand centuries-an estimate which is noticeable as coinciding with the approximative length assigned by others to the period that has elapsed since the commencement of "the post-glacial" era.

And now-to ascend from matters of the earth to the pure and subtle beams of light-we proceed to give a brief résumé of Professor Roscoe's attractive discourse "On the Chemical Action of Light," given on the Friday evening before a splendid audience that crowded the Bath Theatre to the roof. Starting from the doctrine that in all the various forces, such as light, heat, electricity, magnetism, and chemical action, we see only the conversion of one form of energy into another, and remarking that we are now acquainted with the amount of the life-and-force-sustaining heat which the Sun radiates into space, and without which the earth would be a cold and lifeless mass, the professor directed attention, not to the rays which produce heating effect, but to the luminous rays and those which are specially characterised by their power of decomposing certain chemical substances. The heating rays differ from the chemically-active rays only in wave-length and intensity of vibration. Upon the distribution of the chemically-active rays over the earth's surface the animal and vegetable life of a country depend, and the professor described a method of measuring their varying intensity at any given spot on the surface of

the earth. He gave examples of the chemical action of light, the most familiar and popular of which are those afforded by photography-that most beautiful of modern arts-an art which (as is well known) is due to the fact that the yellow, the orange, and the red rays are chemically inert upon the salts of silver. The most complicated example of the chemical action of light is the formation of the wonderful latent image upon the sensitive plate-an image invisible until subjected to the "developing" process. We know nothing as to the kind of decomposition which occurs in its formation: the theory of photography is in its infancy, and the science of the art has not made progress with the practice, and we know little as to the composition of even the visible image. Examples were given of the chemical action of light-that is to say, of the rays which exist at or near the violet end of the spectrum-by showing their effect on elementary gases-viz. chlorine and hydrogen: these chemically-active rays, as is well known, do not pass through a red medium. Perhaps the most important example of the chemical action of light is afforded by vegetable life. The sunlight, acting on the green colouring matter of leaves, decomposes the carbonic acid of the air; the plant assimilates the carbon, and the oxygen is set free for the support of animal life, so that the solar radiations, absorbed by the plant, are given out to animal life in various forms of energy. That the green leaves do absorb the chemicallyactive rays, while leaves not green transmit them, was illustrated by sending the rays from some burning magnesium wire through transparent leaves of the variegated mint placed on the sensitive surface of a photographic plate. For this reason, in photographs, the leaves through which the light has been transmitted appear black. The chemical action of light is capable of measurement, and varies in different climates, as was shown on diagrams; the method employed in making measurements is as capable of use for practical registration as the methods of meteorological observation. The curves of daily chemical intensity of diffused sunlight (or daylight) are registered by means of sensitive paper, and the degree of sensitiveness being constant, it is always coloured to the same tint by the same degree of light. The resulting tints are compared in the monochromatic soda flame which contains no chemically-active rays, as may be seen in its spectrum, which presents one bright yellow line incapable of decomposing the salts of silver. It was by means of this solar line that Kirchoff arrived at the grand discovery of the chemical composition of the sun's atmosphere; so that, although the great solar fountain of light and heat is distant from us ninety-one millions of miles, we now know that iron, magnesium, calcium, and other well-known metals, exist in it. By certain delicate methods, which the professor described, curves of daily chemical intensity can be obtained and registered, and they show the variation caused by clouds or by the different altitudes of the sun; and a difference between the sun's chemical intensity in summer and in winter. Determinations of the chemical action of the total daylight were made at Manchester at the summer solstice, and the winter solstice, and at the two equinoxes, and very great differences were observed, which were exhibited at one view on diagrams displayed in the theatre. Simultaneous observations were made at Heidelberg, where, from the clearness of the air, the total chemical action on a certain day was found to be three times as great as at Manchester, insomuch that Professor Roscoe regards the rays of the sun as intercepted, and only partially experienced