tion through which it passed. Similarly, upon reversing the poles, a green was produced in the first cup, while the middle still remained unaffected. But he soon recognised that there was an exception to this, namely, when the transmitted substance and the medium combine so as to form an insoluble compound; for when it has thus acquired a greater specific gravity than the medium, it is necessarily drawn out of the line of transference; and if by mechanical means it should be preserved in it, the transfer will go on as before.

burns, iron wire dissolves in globules, while charcoal produces a light of such dazzling brilliancy as to fatigue the eye, a property which has been happily seized by employing it in the solar microscope; yet this heat and light are independent of the ambient medium, no oxygen is consumed, and the attenuation of the air rather adds to than diminishes the light. As for the apparent diminution of this intense light when the charcoal is immersed in water, it is attributable to the imperfect conductibility of the latter medium: a thermometer placed in water, in which the wires are immersed, will rise even to the boiling point. It may be observed generally, with respect to chemical Mr. Children has given a list of the order of facility in decompositions effected by galvanism, that it is quantity which substances thus acquire a red heat, and has suc- rather than intensity which is requisite, and that the metals, ceeded in fusing the oxides of molybdenum, tungsten, ura- alkalies, and earthy bases are transferred to the negative nium, &c., but found ruby, sapphire, silex, quartz, &c., pole; the acids, oxides, and chlorides to the positive. By the more intractable. It is obvious that, in the estimation of successive labours of Davy, Wollaston, Brande, Gay-Lussac, such an order, we must take an account of the mass heated, Berzelius, &c., different substances which had before been and of the extent of its surface which is liable to cool by supposed simple, as soda, potash, lime, barytes, strontytes, contact, radiation, or both; and lastly, of the loss of con- magnesia, zircon, &c., were analyzed by this powerful inductibility due to the increase of temperature of the sub-strument; and though silex, alumina, &c., offered great stance interposed. Ether, alcohol, &c., may be inflamed, resistance to its application, and the metallic bases were and gunpowder exploded, by making the discharge through with difficulty restrained from again combining with oxygen, charcoal points. still in the majority of cases the analysis has been successful. The same method was applied by Brande to fluids containing albumen, when albumen and alkali were found at the negative pole, albumen and acid at the positive; he also found that though it remained fluid with a weak battery, when a stronger one was employed it was separated in a coagulated form.

Sir Humphry Davy avoided the increase of temperature in the wires through which the current was discharged by taking them of a length sufficient to discharge the number of pairs of plates employed in the pile, and thus found that the length of wire in this case is inversely proportional to the number of double plates. The diminution of conductibility due to increase of temperature he exhibited by a platinum wire made red-hot by the galvanic current; for when he raised one part of it to a white heat by means of a blowpipe, the heat in the other parts of the wire became immediately reduced. The order of heating in metals, beginning from that most susceptible, which hehas given, is as follows: -iron, palladium, platinum, tin, zinc, gold, copper, silver. The decomposition of water by the battery is effected by bringing the points of the positive and negative wires very near each other under water, inverted glasses being placed over them to collect the gases which are evolved. If the wires be not oxidable, then oxygen gas will be formed at the extremity of the positive wire, and hydrogen at the negative, in the same proportions in which they constitute that liquid; but if oxidable, then the positive wire will be covered with an oxide, while the negative wire still produces hydrogen gas. In general oxygen and chlorine are found at the positive pole, and the other gases at the negative; but we are not to suppose that oxygen only is disengaged by one wire, and hydrogen only by the other; for the particles of water in contact with the ends of either wire are strictly decomposed into their constituent gases, but the oxygen formed at the negative wire is transferred to the positive, and the hydrogen at the positive is transferred to the negative.

The chemical analysts were at first somewhat puzzled at finding foreign products, when producing decomposition by galvanism; soda, which was sometimes found, was due to the decomposition of small portions of the glass in which the experiments were made, and muriatic gas to vegetable substances employed occasionally, as wet cotton-thread, when the liquid was contained in separate vessels having only this mutual communication.

When neutral salts were held in solution and exposed in the same manner to the galvanic action, their alkaline bases were found at the negative wire, and the acid at the positive: thus zeolite was decomposed into soda and lime; common salt into solution of soda and sulphuric acid; while the metallic solutions gave their crystals and oxides to the positive pole, and transferred the acids to the nega tive. Davy made the remarkable discovery that this transfer took place without any combination being effected with the parts of the medium traversed, even when the latter had a great affinity for the elements which passed through it. He arranged three cups, in the first of which was a solution of litmus (a well-known chemical test), in the second a similar solution, and in the third sulphate of soda. The positive wire was immersed in the first cup, the negative in the third; and the intermediate was connected with the two extreme cups by a moistened thread, so as to complete the circuit: the result was, that the solution of litmus in the positive cup became red, indicating the transfer of the acid from the third cup, while the similar solution in the intermediate cup underwent no change, clearly showing that the acid in its transfer did not combine with the solu

Experiments of the same nature have been recently made by Mr. Golding Bird, whose results do not agree with those obtained by Brande. He used for his battery the Voltaic form, a Couronne de Tasse,' of thirty small plates, excited only by a weak solution of salt, and first operated on liquid albumen in a state of non-combination. Putting serum of blood into a glass vessel, and having introduced the wires of the battery, a cloudy deposition took place near the positive wire without adhering to it. The experiment being next made with two vessels connected by moistened cotton, coagulation took place in the positive vessel, while none occurred in the negative; after a time the contents of the former had an acid taste, and of the latter a caustic alkaline flavour: when all in the positive vessel was coagulated by the galvanic action, he found there hydrochloric acid mixed with chlorine, and the alkali in the negative vessel. He has given also an explanation of the causes of the difference in Brande's results.

An interesting class of experiments are due to Mr. Crosse on the employment of electricity, in a state of high tension, to form mineral and other substances. There is a cavern near Broomfield, of which the vault is covered with arragonite and carbonate of lime and fine crystals. The water which drips from this vault holds in solution ten grains of carbonate of lime and a little sulphate of the same to each pint. A glass filled with this water was submitted to the action of a battery consisting of 200 pairs of plates, and at the expiration of ten days the negative pole was found to have formed rhomboidal crystals of carbonate of lime, accompanied by some gas-bubbles, and in less than a month after the wire was covered with regular and irregular crystals, whence it follows that the bi-carbonate was decomposed into carbonate and carbonic acid gas. He also let the water drop on a piece of brick subjected to a current from 100 five-inch plates, the brick being supported by a funnel which conducted the water into a vessel below after four or five months the brick near the negative pole of the battery was covered with carbonate of lime, while near the positive pole were disposed prismatic crystals of arragonite; and the same experiment being repeated with fluosilicic acid, regular hexahedral pyramids similar in all respects to quartz were obtained; those which were left in a dry place acquired sufficient hardness to scratch glass; the others had not that power, and gradually lost their transparency. In his varied experiments of this nature he has succeeded in forming, by means of the galvanic battery, the following minerals:-carbonate of lime; arragonite; quartz; protoxide of copper; arseniate of copper, and its blue and green carbonates; phosphate of copper; carbonate of lead; chalcedony, &c., upon which Becquerel remarks, in the last-published volume of his 'Experimental Electricity,' Nearly all these substances we have obtained these dozen years with the simple electro-chemical appa ratus.'

of newly killed frogs were at first used; but the discovery of electro-magnetism has furnished a more delicate and measurable criterion: the instrument founded on this principle has been successively improved in the hands of Schweigger, Cumming, Nobili, and Melloni, to a most remarkable degree of delicacy.

The principle of the construction depends on the property possessed by electrical currents of acting on magnetised needles; for if the conducting wire be placed on the magnetic meridian above or below the needle, the latter will suffer a deviation to the right or left according to the direction of the current.

The action of terrestrial magnetism tending to restore the needle, after its derangement by the current, to its original position, is almost entirely corrected by employing two similar needles supported parallel to each other by a light piece of straw or other substance, and placed with the poles of one in an inverse position to those of the other. This apparatus being suspended by a fine silk thread, is placed in a wooden box of the form of a parallelopiped of small width, round which the conducting wire is passed in a great number of coils, which are kept from communicating by being doubly wrapped in silk or other non-conducting substance; the number of coils in some such instruments has been more than 500, by which the effect produced on the needle by a single current is multiplied twice as many times, since the opposite sides of each coil double the action of either side; and the terrestrial polarity of the needle being counteracted in the manner above mentioned, this simple instrument acquires a very great sensibility.

Modifications of the above construction have been made by Person, Peltier, and others, and a moveable index has been attached, particularly when weak thermo-electric currents are to be examined. Four needles have been used by some instead of two, but the principle of the construction in all cases is the same as that which has been described. On the construction of electroscopes and galvanometers, the reader may consult Annales de Physique, t. xvi., p. 91, by Bohnenberger; t. xxii., p. 358, by Oersted; t. xxxiii., p. 62, by Colladon; t. xxxviii., p. 225, by Nobili; t. xlviii., p. 113, by Nobili and Melloni. Also Biblioth. Univ., t. xxxviii., p. 79, by Nobili; Phil. Trans. 1823, by Pepys; also Annals of Philosophy, 1824, &c.

GALWAY, a maritime county of the province of Connaught, in Ireland; bounded on the north by the county of Mayo; on the north-east by the county of Roscommon, from which it is separated for the most part by the river Suck; on the east by parts of the counties of Westmeath, King's County and Tipperary, from which it it separated by the river Shannon; on the south by the county of Clare, and on the west by the Atlantic Ocean. It extends from 52° 57' to 53° 42′ N. lat., and from 7° 53′ to 10° 15′ W. long., being about 164 English miles in length from east to west, and 52 in breadth from north to south. The extent of coast, which is very irregular, has been estimated at 400 miles; and the Shannon and Suck, both navigable rivers, nearly surround the rest of the county. The area, according to the Ordnance Survey, consists of-cultivated land, 955,713 acres; unprofitable bog and mountain, 476,957 acres; water, 77,922 acres; or 2360 statute square miles. The population, exclusively of the county of the town of Galway, was, in 1831, 381,564.

country east of Loch Corrib is more diversified with hill and dale, and is generally in a good state of improvement. The | centre of this eastern district of Galway is a bare flat tract, not equal in fertility to any of the other portions. The whole district west of Lochs Corrib and Mask is known by the general name of Connamara, and has latterly attracted much attention by its capabilities of improvement, as well as by the uncommon wildness and beauty of its scenery. The bay of Galway bounds it on the south, the Atlantic on the west, and a deep inlet of the sea, called the Killery harbour, separates it on the north from the mountainous district of Murrick, in Mayo. From the head of Loch Corrib on the east to Achris Head on the west, this district extends 40 English miles; and from the head of Killery harbour on the north, to the shore of the bay of Galway on the south, 30 miles. The most prominent object is a group of conical mountains called the Twelve Pins, (probably Bins, synonymous with the Scotch Ben), of Bunnabola, rising abruptly from a table-land of moderate elevation which stretches south and west from their bases to the sea, and forms the chief habitable portion of the district. Round their bases are numerous lakes, of which the chief are Loch Ina, under the eastern front of the group; the upper and lower lakes of Ballinahinch skirting them on the south, and Lochs Kylemore and Foe lying between their northern declivities and the opposite range, which rises along the southern shore of the Killery. The average height of these mountains is about 2000 feet; some rise to 2400 feet, and as the table-land from which they rise is only of mode. rate elevation, their appearance is very striking. Northward and eastward from the Twelve Pins a range of equal altitude, but not of so picturesque a character, covers an area of about 200 square miles, between the head of Killery harbour and the western shore of Loch Mask. About midway between these waters lies the lake of Loughnascoy, north of which, to the boundary of Mayo, the country is entirely uninhabited. The chief elevations of this group, on the west, are Shanafola, at the head of Loch Corrib; Ben Leva, the declivities of which form the isthmus between Lochs Corrib and Mask; and the range of Maam Trasna overhanging the western shore of the latter lake. On the north the range of Furmnamore extends along the Mayo boundary, and on the west and south Maam Turk and Mameam rise over Loch Ina opposite to the eastern part of the group of Bennabola. Although this entire tract of country is generally known by the name of Connamara, it is properly divided into three districts: the portion last described, between the head of the Killery and Loch Corrib, being termed Joyce Country; that lying south of the Pins and range of Shanafola and Mameam being Iar-Connaught, or Western Connaught; and the remainder, extending westward from the Pins to the Atlantic, constituting Connamara Proper. The islands off the coast of Galway are very numerous; the chief are the three south islands of Arran, lying about midway between the coasts of Iar-Connaught and Clare, in the opening of the bay of Galway, and the islands of Innisturk, İnnisboffin, and Innishark, extending, in like manner, across the offing of Killery harbour, between the coasts of Connamara and Murrisk.

On the southern side of the bay of Galway the coast is not favourable for the construction of harbours. From Burrinquay, in the county of Clare, to Kinvarra, at the Physical Character, Rivers, Coast, &c.-With the excep- head of the bay, there is no place of shelter for craft except tion of a spur of the Slieve Boughta mountains, running at Killaney in Arran, and Durus on the mainland, opposite from the Clare boundary on the south-east towards Loughrea, the town of Galway. The creeks of Ballynacourty and and a similar extension of the Burrin range [CLARE] on the Rhenville are good harbours for vessels of a small class south-west of the same district, the whole of that part of at the head of the bay, and the harbour of Galway has Galway which lies east of Loch Corrib, being nearly of the lately been much improved. Westward however from same extent with the county of Tipperary, is comparatively Galway, and round the entire coast of Iar-Connaught flat, and although to a great extent encumbered with bog, and Connamara to the boundary of Mayo, there is a sucis pretty generally improved and productive. A low table- cession of harbours for vessels of the largest class, unland running north and south separates this part of Galway equalled perhaps on any similar extent of coast in Europe. into two nearly equal districts, the waters of one of which The first of these noble roadsteads next Galway is Costello run eastward into the Suck and Shannon, and those of the bay, at the mouth of the celebrated fishing-stream the Cosother westward into the head of Galway Bay and Loch tello, where a small pier was erected in 1822 for the acCorrib. The district of the Suck is most encumbered with commodation of fishing-boats and merchant vessels. This bogs; nevertheless it contains much well-improved land, harbour admits large ships, and is defended by a martello particularly in the neighbourhood of Ahascragh and Balli- tower. Casheen bay, Greatman's bay, and Kilkerran bay nasloe. The district bordering on the Shannon also con- occur immediately west from the Costello, being separated tains a large portion of bog on that side next the river, but from one another by narrow peninsulas. The last-mentioned has a good share of cultivation and improvement towards bay contains one hundred miles of shore, and is capable the interior. The district extending eastward from the of receiving the largest vessels. A pier, five hundred feet head of Galway Bay is the richest part of the county Thein length, with a return of one hundred, was constructed

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here in 1822; but as there is no road of any kind to the shore, it has been of comparatively little service. An extensive peninsula (ten miles by seven), interspersed with lakes, but destitute of roads of any kind, separates Kilkerran bay from the bay of Birterbuy, which runs inland about five miles, being only half a mile wide at the entrance, and from two to three miles wide within; it has deep water and fine ground, and might be easily fortified, so as to form a most desirable station for ships of war. On the western side of the entrance to Birterbuy bay is the opening of Roundstone harbour, a safe and capacious inlet, with clean good ground, and two to five fathoms' water. Roundstone harbour has been much spoken of as the terminus of a western Irish railway. At the head of the harbour, where the waters of the lakes of Ballinahinch and Loch Ina discharge themselves, is an excellent salmon fishery. A considerable village has sprung up within the last ten years at Roundstone, and as a road runs hither from the main line of communication between Galway and Clifden, there is a prospect of it becoming a place of some trade, especially as it is the nearest point for the shipment of the fine green marble of Ballinahinch. From Birterbuy the coast stretches, with occasional anchorages, to Slyne Head, the most western point of Galway; off Slyne Head lie a number of islands with navigable sounds between them, which remained unnoticed in the maps till Mr. Nimmo's coast survey, made for the late Commissioners of Irish fisheries: had the existence of these sounds been known, it is believed that many shipwrecks might have been prevented. Between Slyne Head and Achris Head occur the bays of Mannin and Ardbear, or Clifden; the former possessing one good anchorage, but exposed, and the latter an excellent harbour with safe anchorage in six to eight fathoms' water. At the head of this harbour a considerable town has grown up since 1822, at which time it consisted only of one slated house and a few thatched cabins. The commencement of a pier here by the proprietor, Mr. D'Arcy, assisted by Government in 1821, seems to have been the first step towards raising the place above the wilds which still surround it. So successful have the efforts of the proprietor been, that Clifden, in 1826, contained about one hundred good houses, roofed with Bangor slates, and about thirty country shops, the sales of which were estimated to contribute upwards of 3000l. per annum in direct taxes to the Government; and the consumption of taxable commodities is now stated to have increased to double the amount. In 1821 the population was 290; in 1831 it was 1257.

fifteen thousand pounds' worth has been manufactured in one season. Banks of calcareous sand and beds of limestone are of frequent occurrence, and there is an inex haustible supply of peat fuel and of water power. Yet, notwithstanding these capabilities, if the neighbourhoods of Clifden and Roundstone be excepted, the population still continues poor and thinly scattered along the coast, leaving the interior almost wholly waste. The population of this district is at present under 65,000, and the entire rental about 50,000l. per annum; although it is estimated to contain 350,000 Irish, or 615,000 English acres.

The rivers of Galway, being either feeders of the Suck and Shannon, or descending by short courses from the western district to the sea, are in general small. The river of Clare-Galway, which rises near Dunmore, in the north-east of the county, and passes near Tuam, has a course, from its source to its termination in Loch Corrib, of about 50 English miles. South of Tuam it expands into a periodical lake or turlogh: the waters generally rise in September or October, and do not subside until May, after which a coarse grass springs up, which is generally grazed as a common by the tenants of the adjoining land. Similar turloghs mark the surface of the country throughout the entire district bordering on the county of Clare; a phenomenon which is probably owing to the porous nature of the limestone rock which forms the substratum, which, being saturated with the autumnal rains, ceases during the winter to absorb the surface waters. Here, as elsewhere, on the verge of the great limestone tract which extends throughout the central district of Ireland, it is frequently perforated by subterranean cavities, which occasion the disappearance of numerous streams, and in some instances absorb considerable rivers. Thus, the river of Shruel, on the northern border of this part of the county, dips underground near Moycastle, and emerges before it terminates in Loch Corrib. The entire waters of Loch Mask also pass more than two miles by subterraneous channels under the isthmus of Cong into Loch Corrib. A considerable stream, which rises near Loughrea, after a south-western course of ten miles, during which it dips underground for half a mile, disappears in a turlogh about five miles from Gort; and two other streams in the more immediate neighbourhood of Gort sink and emerge frequently, and finally disappear without any visible outlet. The lakes of Loughrea and Gort are fine sheets of water; the latter has well-wooded banks and a very picturesque vicinity.

An extension of the Grand Canal connects Ballinasloe with the line to Dublin at Shannon Harbour. It has been proposed to carry on this line by Tuam to Galway, and to extend a branch from it to Loughrea. It has also been proposed to open a water communication northwards from Galway through the heart of Connaught by joining Lochs Corrib and Mask with the navigable lakes of Mayo. [CONNAUGHT.]

There is now a regular market in Clifden for corn, where, ten years ago, all the corn required was brought in barrels from Galway. A brewery, distillery, and milling concerns contribute principally to the demand; but there is also a regular export of corn and butter to Liverpool. As early as 1825 there were seven cargoes imported direct into Clifden for the use of the country; and there is now a regular import from America. North of Clifden harbour Prior to 1813, the only roads west of Galway were a naris Cleggan, an excellent roadstead, with a pier built in 1822, row coast-road to Costello bay and a central road by to which a branch of the new coast-road has been extended. Oughterard to Ballinahinch. These were led over rocks Between Cleggan bay and the point of Renvyle, which and bogs in so unskilful a manner as to be scarcely passable forms the southern boundary of the entrance to the Kille- for any sort of carriage, and the only other means of comries, is the harbour of Ballynakill, well sheltered by the munication through the district were narrow bridle-roads island of Truchelaun, and capable of receiving vessels of scarcely passable for horsemen in summer, and quite imthe largest class. Rounding the point of Renvyle there is practicable in winter. On the coast, in particular, there was an open bay, from the head of which two inlets run east-nothing beyond the Costello better than a footpath. By ward between steep mountains. These are the Great and the improvements begun in 1822 and still in progress under Little Killeries; the latter an arm of the sea, about twelve the Government, a complete line of carriage round the miles in length, by a quarter to three-quarters of a mile in whole district has been effected. A coast-road has been width, having, for a great part of its length, ten to twelve formed which touches the heads of all the chief inlets from fathoms of water and clean ground. An island at the Costello bay to the Killery, where it joins an inland line mouth completely protects it from the sea, but from being leading through the heart of Joyce Country to the head of overhung on each side by steep and lofty mountains it is Loch Corrib, and thence across the central plain of Iar Conexposed to squalls, and not safe for sailing boats. The naught to the southern coast-road at Costello bay. These scenery of the Great Killery is much admired, and considered to approach nearest to the Norwegian fiords of any fishing harbours on the coast, have considerably promoted works and the expenditure of public money on piers and in these islands. On the whole there is no part of this dis- the general prosperity of the country; and the favourable trict more than four miles from existing means of naviga- statements of the various scientific men engaged in them tion. The harbours fit for vessels of any burthen are upwards have attracted so much attention to Connamara that there of twenty in number; it contains twenty-five navigable lakes is a probability of its ultimately becoming the scene of exof a mile or more in length, and hundreds of smaller size. tended mercantile and agricultural speculations. Loch Corrib and Loch Mask alone have upwards of seventy miles of navigable coast; and all these waters abound with fish. The sea-shore affords a constant supply of red and black seaweed, which can be used either as manure, or in the manufacture of kelp, of which latter article upwards of

Climate. The climate is mild, and snow rarely lies in the western district. Cattle in this part of the county are never housed. The summers are wet, and the coast is ex posed to very heavy storms from the Atlantic. According to the population returns for 1821, there were living in the