.5TV i TREATISE ATMOSPHERICAL ELECTRICITY; INCLUDING LIGHTNING RODS AND PARAGR&LES. ftcconn (EEtJition. BY JOHN MURRAY, F.&A. F.L.S. F.H.S. F.G.S. &c. &c. " The hail smote every herb of the field, and brake every tree of the field."" The thunders and hail ceased, and the rain was not poured on the earth. " EXODUS, chap. ix. LONDON: WHITTAKER, TREACHER, AND ARNOT, AVE-MARIA-LANE. 1830. LOAN STACK LONDON : Printed by A. & R. Spottiswoode, New-Street-Square. TO RICHARD ELLISON, ESQ. SUDBROOKE HOLME, LINCOLN; THE AUTHOR, IN RESPECTFUL ESTEEM, INSCRIBES THIS TREATISE ON ATMOSPHERICAL ELECTRICITY. A 2 827 ADVERTISEMENT. THE following Treatise on the curious and interesting question of Atmospherical Electicity is introduced to public notice, with almost exclusive reference to Lightning Rods, as they are usually termed, and their congeners, Paragreles, for the principle of both is the same. In order, however, to modify the question, and make it somewhat more general, a succinct view of Historical Electricity immediately follows the preli- minary remarks, and in the sequel will be found the precautions necessary for personal security^ in the storm. A renewed interest has been excited by some recent remarks on Conducting Rods, on the part of Lieutenant Green, which we believe has even gone far to unsettle the faith of the British Government in their hitherto unsuspected efficacy. Though the phenomena of the Paragreles may be a novel feature in the sub- ject, in reference at least to this country, we feel con- fident in the successful results they promise, far more efficient than Lightning Rods in local protection, they extend our views of their practical value, and presage benefits which we had not contemplated as within the sphere of their influence. December 1. 1829. A 3 DESCRIPTION OF THE FIGURE FORMING THE FRONTISPIECE. A. A pole of wood, which may be from 35 to 50 feet long. B. The earth into which the pole is sunk to the depth of about 3 feet. a The termination of the brass or copper wire ; it is 3 or 4 inches higher than the summit of the pole, and sharpened to a point. b. The brass or copper wire, attached to the pole in all its extent, resting in a shallow groove channelled in the wood. This wire should be about one tenth of an inch in diameter. c. Small rings, which fasten the wire to the pole, and prevent its displacement. d. A small transverse pin, which secures the conducting wire at the bottom of the pole. e. Thorns, brambles, or furze, surrounding the pole, to secure it from injury, or prevent an incautious approach. The wood should be varnished, to preserve it from moisture, and the better to insulate the conducting wire ; while that part of the pole which enters the earth should be charred, to prevent decay. PREFACE TO THE SECOND EDITION. IN consigning this new Edition to the public, I have endeavoured to evince my sense of the favour with which the former has been received, by renewed en- deavours to make the present more acceptable. Many additional facts will be discovered throughout, a few alterations made, and the extracts from the Shrewsbury Chronicle, as deemed an unnecessary ex- tension, withdrawn. It would be ungrateful in me to pass unnoticed here the friendly suggestions contained in the Monthly Review of February last ; and I may, in explanation, observe, that it never was my intention to enter into any thing like an elaborate discussion of the important subjects I have very briefly endeavoured to propound : my object being simply to put the public in possession of some facts, which appeared to possess a national, as well as an individual, interest ; leaving its more ab- struse phenomena for others better qualified for the task than myself. I have not, indeed, " noticed the ar- guments and speculations of adversaries at any thing like an adequate length ; Leslie, though not formidable, being scarcely mentioned :" to have done so, would have increased the magnitude of the volume beyond the limits originally contemplated ; and I have been careful throughout to confine myself chiefly to facts, Vlll adverting only incidentally to theories, and that merely when essential. My reviewer is pleased to think that I have satisfactorily answered Mr. Leslie's assertion, where he says, " It never can be proved that Thunder Rods have produced beneficial effects; but severa 1 instances may be cited, where they have afforded no sort of protection whatever." The recent case of the gunpowder magazine destroyed at Bayonne is, I believe, the last instance on record. It is, I think, very properly observed, that his remarks are " a mere academical display a brilliant chain of theories, and, as a piece of reasoning, perfectly suicidal ;" for it is surely ridi- culous, after this condemnation of Lightning Rods, to proceed to directions about their adoption, and to draw the inference he does from the circumstance of a heated ball effecting a more facile discharge of accu- mulated electricity, which, if it were to the purpose, would prove too much. Indeed, I more than suspect some error in the experiment : it has not succeeded with me ; and it is very doubtful whether heated air be a conductor, such as this phenomenon would lead us to suppose. The experiment made by the late Mr. Singer with the electroscope in a heated oven, where the gold leaves still remained divergent, seems to prove that it is not. The discharge of an electrified sphere by flame is quite a different question ; since it is not doubted that flame, and the produce of its com- bustion, carbonaceous matte are conductors. Mr. Leslie, however, arrives at the conclusion, that a chimney is a better conductor than a Lightning Rod ; but since the chimney is lined with sooty carbon, and one flue at least in every house is constantly supplied with fuel and flame, no legitimate conclusion can be drawn from Mr. Leslie's experiment. It may, indeed, account for the circumstance of houses in a crowded IX city or town being so rarely visited by the effects of Lightning, while insulated buildings, or trees apart from the main group, become victims of the meteor ; since there may be several among the many chimneys thus congregated, in contact with the ground. Our Author cannot surely forget that Lightning, after it has effected its descent by the chimney, frequently commits much mischief, and displays its power in a terrible manner ; and a chimney can seldom, if ever, be a safe substitute for a conductor it invites the enemy within the walls, and there leaves the fell destroyer, because its continuity with the earth is dissevered. I have in this Edition incorporated an interesting account of the effects of a thunder-storm in the city of Lichfield, for which I am indebted to the kindness of a connection of the family. The Lightning descended the chimney ; and, indeed, this is almost always the case. I have not supposed it at all necessary to enter upon Lieutenant Green's speculations on Electricity, since they seem to me to run counter to well established laws ; and I have never denied that Lightning Rods, as they are called, and as generally constructed, are mis- chievous things, though I feel confident that Mr. Green's views will not mend the matter. A contro- versy took place in one of the Plymouth newspapers, between this gentleman and Mr. J. N. Hearder ; it was, however, chiefly personal: the latter has endea- voured to prove, that although a conductor be destroyed, the building will remain uninjured! This astound- ing enunciation, I must own, startled me not a little. The destructive effects of the lateral explosion are altogether overlooked. Mons. Gay Lussac's proposition has only been in- cidentally adverted to, though certainly worthy of a more minute scrutiny, as emanating from one of the first philosophers of France : his plan is, however, by no means faultless, and may well be questioned in many of its parts : thus, e. g. the recommendation to tar the " strand " which forms the conductor ; ard here I am aware it may be stated, that a varnished, or even tarred, metallic rod will still conduct electricity : this ?s quite true, and not denied; but it must be also evident, that it will do much better without being var- nished ; and the less its conducting character is dimi- nished, the safer is the Lightning Rod. Just so is it with a film or shell of glass, through which Electricity will readily pass ; and yet it is not denied that glass is an electric : and so is resin, as well as varnish. To attenuate the amount of resistance, whether considered in entrance, transit, or exit, it is palpable, must be an object of first-rate importance. Thus, if the recipient ball be covered with flannel, the amount of illuminating power in the spark, in reference, to luminous devices formed with patches of tinfoil, will be greater, from the resistance of the fold or folds of interposed flannel ; and additional proofs and illustra- tions will be found incorporated in the Work. The oxidation which the tar is intended to prevent, is amply provided against by the plan I have suggested, of a cylinder of zinc, through which the fasciculus of wires is finally threaded on its entrance into the earth, the principle being precisely that of the late lamented Davy. J. M. June 1. 1830. TABLE OF CONTENTS. CHAPTER I. Page Introduction - 1 CHAP. II. Historical Sketch - _ 4 CHAP. III. Meteorological Phenomena subordinate to and dependent on Atmospheric Electricity. Different Electric States of the Atmosphere. Aerial Electroscopes. - 17 CHAP. IV. Heat and Moisture, their Relations to Aerial Electricity. De Luc's Electric Column Its Application to Chrono- metry. Canton's Bells. - -22 CHAP. V. Lightning identified with Electricity. Meteoric Phenomena. Bolides. St. Elmo's Light. Aurora Borealis. Meteoric Stones. Electricity of Volcanoes. - -27 CHAP. VI. Phenomena of Vegetation. Dutrochet's Theory. Animal Electricity. Ascent of the Spider. - - 54 CHAP. VII. Unequal Distribution of Temperature. The Meteorological Features of the Clouds dependent on their Electric Cha- racter. Dew. Rain. Hail. - - - 7 1 xn CHAP. VIII. Pago Description of the Thunder Storm Personal Security in the Storm Effects of Lightning. Paralysis cured. Magnetism communicated. Beneficent Ministry of the Thunder Storm. - - - 84 CHAP. IX. Thunder Rods Their Attachment to Buildings, and to Ships at Sea. The Paragrele. Influence on the Storm Cloud. Extensive Utility. Change of Climate. 102 ATMOSPHERICAL ELECTRICITY, &c. CHAPTER I. INTRODUCTION. ATMOSPHERICAL Electricity embraces a wide field of enquiry, and involves not only questions of curious interest, but subjects of vast practical utility. If the recommendation relative to the general adoption of Paragreles be followed up, it is impossible to cal- culate the ultimate amount of good; nor does it wear even the guise of being a problematical issue, , but rather a conclusion naturally flowing from the in- ductive truths of electrical science, established on the known laws which regulate and control its pheno- mena. It seems, indeed, to bear the features of national importance, and even to recommend itself to the dis- passionate consideration of the landed interest, nor can the wisest describe or estimate the final conquests and triumphs which the genius of science may achieve, and, if a solitary metallic rod can command the heavens to yield their lightnings to its potent spell, what may not reasonably be expected from an immense army of marshalled points extending far and wide ? In those parts of America where the thickets have been cleared, it lightens rarely, and the thunder's peal is never heard. When " the axe was laid to the root of the tree," the thunders were chased into the woods, and the lightning's flash serves now merely to illuminate the back ground of the forests gloom : it is thus evi- dent, that man possesses in the employment of judi- cious means, gleaned in the harvest-field of science, a vast control over the otherwise formidable obstacles of nature. By the drainage of the Pontine marshes, under the auspices of Napoleon Buonaparte, even the sallow and sickly hue of the visage, marred by the pestilential ravages of the malaria, assumed the glow .,vf health, and laid aside the vestment of disease ; and in our own country intermittents, once so rife, have scarce " a local habitation or a name/' The field of electrical research is varied with many wonders, and is rich in interest ; and though its phenomena are very subtile in their nature and relations, they are not on that account the less valuable and important. Elec- tricity cannot, like many forms of matter, be weighed in the balance, or its amount computed by a scale of equivalents, neither can it be confined within the tram- mels of mathematical formularies, as it often bids de- fiance to philosophical rules, and overleaps their pre- scribed pale. These circumstances, conjoined with other causes, such as the Protean forms of expression which it often assumes under the hand of the best experimentalists, seem in many cases to have wearied out its votaries ; and this branch of science at the present moment boasts of few successful cultivators : notwithstanding all this, the importance of the subject . is not lessened, nor its interest diminished. Light- ning is identified with its playful diversities and beautiful forms, merely borrowed for a time from its aerial treasury the theatre of its grandeur and majesty : the quantities we meddle with are, indeed, comparatively small, but it is lightning still, and those mimic fires that sparkle and explode may yet assume a loftier flight, become an integrant part of the forked terrors of the sky, and serve to swell the thunder's peal. Considerations such as these should kindle up an intensity of interest, awaken the powers of curiosity, and whet our intellect for the study of its mystic won- ders ; is it not a sublime and imposing spectacle to stand by and contemplate science connecting, as it were, the heavens with the earth by a slender metallic rod, and presently witness the lightning descend upon its summit in all its terrible grandeur, and finally glide into the bosom of the earth in harmless corruscations ? The rival scene may be sought for, but is no where to be found. When studying electricity, we are in- vestigating the mightiest and most mysterious of na- ture's powers, interrogating its laws and agencies, and making lightning subservient to experiment by introduc- ing such quantities only as can be safely managed in our scrutiny: for science can describe her magic circle round this formidable power, and within that barrier it may be handled and examined with impunity. B 2 CHAP. n. HISTORICAL SKETCH. THE history of electricity is very instructive : the developement of its curious facts and phenomena has not been the triumph of a day ; on the contrary, their revelation rather, like the expansion of the flower, has been slow and gradual, the purchased reward of continued toil and active perseverance, while the picture of its history unveils the fact, that by far the greater proportion of the discovered phenomena is fairly ascribable to what we usually call accident, or such as we casuallv meet with or stumble upon in our search after truth, and comparatively little will be found to be the genuine offspring of the slow and sober calculating process of induction. Men are not fond of acknow- ledging the unwelcome position, but its truth is not unhinged by the reluctant confession, and as the cir- cumference of human intellect can only enclose a limited number of the wonders embosomed in nature, an honest confession would appear most creditable. The great mass of discovery will be found, if weighed in the balance of truth, to be in a similar condition, and it reads to us the important lesson, that unwearied and assiduous perseverance in the field of experiment will certainly be rewarded by the meed of unexpected and in- teresting facts. Electricity is even yet an inexhausted mine of enquiry, and its votaries have much to learn and much to discover : the interest interwoven with the question is indeed great, considered in its charac- ter as a science. It is the subtile and mystic agent to which meteorological phenomena are subordinated : it presides over the silent assimilations of vegetation, and extends even to the chemical processes and functions of animal being, under the control and direction of the principle of life. Thales of Miletus, who flourished about 600 years before our era, had discovered that amber, when rubbed, manifested the peculiar property of attracting light bodies when brought near it ; vjXfivcrpov (elektrori) is the Greek word signifying amber, and this is derived from the verb eX*a (elko) to draw : hence amber pos- sessing this peculiar manifestation is thus indicated, and those substances which acquire a similar property by friction are in like manner called electrics ; while the science which treats of their phenomena is appo- sitely called ELECTRICITY. Theophrastus of Eresus records the same thing of jet and agate, while he in- cludes the lyncurium, perhaps the tourmaline of modern mineralogy. These insulated facts, with the shocks of the torpedo, and the sparks elicited from the animal frame under peculiar circumstances, considered as so many separate phenomena, complete the summary of the wisdom of the ancients on this question. Their conclusions, too, were always tinged with the colouring of the schools in which they were taught, and possess little weight or importance : in the Ionic school, for instance, motion was identified with mind, and it was therefore believed that the amber became animated by the mere circumstance of friction. It thus appears that electrical science is the offspring of modern times, and its more imposing and important pheno- mena may date their rise and progress from the year 1600, when Dr. Gilbert, in his treatise on the Magnet, supplied us with a catalogue of various substances which became electric by friction. From this period the tide of discovery swells in magnitude, and accu- B 3 mulates in force in a regular and remarkable ratio, till it bursts upon us in the full blaze of Galvanism, and all its ramifications of electro-chemistry, electro- magnetism, thermo-electricity, and the magnetism of light the effect doubtless of the electricity indi- genous to light and colour. The list supplied by Gilbert was extended by the Honourable Mr. Boyle ; the latter also discovered the electric light emitted from the diamond by friction, and found that light was also produced under similar circumstances by other electrics : Mr. Boyle, however, considered this light to be a distinct character of its agency. Dr. Wall appears also to have obtained electric light by rubbing amber on flannel, while Otto Guerike, the pro- consul of Magdeburgh, constructed an electric globe of sulphur, and received electricity from it by rubbing it with his hand, while it revolved on its axis. In a work, published by Mr. Hawksbee, in 1709, the electric property of rubbed glass is described, the light and noise that accompanied the exhibition, together with a variety of other phenomena connected with it, as those of attraction and repulsion : he appears also to have used in his experiments a re- volving glass globe. Mr. Stephen Grey, characterised as a very assiduous experimentalist, succeeded by means of a hempen string in conveying the electric matter from his balcony to an ivory ball suspended by it in the court below, but on subsequently attach- ing this hempen line by means of loops of packthread, in order to transmit electricity in a horizontal direc- tion, he could not succeed. Mr. Wheeler and he then proposed that loops of silk should be substituted for the packthread, which they concluded had from its greater size counteracted the effect : by using silk thread they succeeded completely ; and it was ulti- mately discovered that the cause of their failure in the former case, and their success in the latter, was not to be ascribed to the size, but to the peculiar quality of the material employed, and from this very simple ac- cident arose the distinction between conductors and non-conductors of electricity. Mr. Grey also placed a wooden dish containing water on a cake of resin, and having communicated electricity to it, found that light and buoyant substances were alternately at- tracted and repelled from its surface had the ex- periment been pushed a little farther, the discovery of accumulated electricity would have been complete ; this, however, was reserved for another period of its history. Dessagulliers first proposed the distinctive and characteristic terms of electrics or non-conductors, and non-electrics or conductors: because the former by friction possessed the property of manifesting the phenomena of electricity, but could not convey it away; while the latter, though they could carry it off, were incapable of producing it by friction. * In the year 1732, Mons. du Faye found, during the repetition of Mr, Grey's experiments, that all bodies, whether solid or fluid, were susceptible of receiving electricity, on the approach of an excited glass tube, such being placed on glass, or sealing-wax, provided the supports were perfectly dry. In his experiments, we find that ice, among other substances, was tried as an electric with success, and globes of ice may certainly be used as electrical machines, while pieces of ice, by mutual friction, will even evolve sufficient heat to liquefy them. One experiment, among others, made by Du Faye merits particular mention : having suspended * This is merely a general position, since copper filings sifted through a sieve of zinc, and, vice versa, affect the electroscope: friction is the medium, not the cause. B 4 8 himself by silk cords, he was electrified in this con- dition, and the Abbe Nollet received from him the electric spark, the first ever drawn from the human frame. The merit of having first advanced the theory of the existence of two distinct and peculiar electrici- ties belongs to Du Faye, and these were termed vitreous and resinous, corresponding to the sources of production and obtainment, the vitreous electricity being the produce of the friction of glass, and the resinous that of resin, and other similar bodies. The announcement of the preceding facts led to more ex- tended enquiries, and the number of its votaries pro- portionally increased. About the year 1742, Mr. Boze of Germany re- introduced the globe employed by Hawksbee, as a substitute for the tube, which appears after that period to have been exclusively used in experiments : he also suspended an iron cylinder, by means of silk cords, to serve as a conductor, and a fringe of threads, attached to one end of it, served to collect the electricity ex- cited by the revolution of the globe. Mr. Winckler applied a cushion, the hand having been previously employed in all experiments ; the human frame, in contact with the earth, its fruitful source of supply, being the medium of communication. For the cylin- drical form of the machine, we are indebted to Mr. Gordon, and the plate electrical machine was intro- duced by Dr. Ingenhouz. With this improved and powerful artillery of appar- atus, the field of experiment became brighter and more enlivened. Dr. Watson exhibited a great variety of experiments, new and curious at that period, such as the inflammation of spirits of wine, and other com- bustible substances : he excited no less than four glass globes at once, and, agreeable to his own description, the electricity was so intense and brilliant, that when " two pewter plates were held, one in the hand of an electrified person, and the other in the hand of one who stood on the floor, the flashes of pure and bright flame were so large, and succeeded each other so fast, that, when the room was darkened, he could distinctly see the faces of thirteen persons, who stood round the room." The year 1746 stands a brilliant point in the annals of our science, and was crowned with the beauti- ful discovery of accumulated electricity, by means of which a vast accession of power was gained, increasing with the multiplication of the apparatus and extension of the surface. It has been stated, that to Mr. Von Kleist is due the germ of the discovery we are about to communicate, who employed a phial, having a blunt piece of wire loosely inserted into it. Be this as it may, Professor Mushenbroeck associated with Messrs. Cuneus, Allemand, and Winckler, were making experi- ments with water, in glass bottles or jars, but, whether with reference to the experiment attributed to Von Kleist, or founded on a supposition that a modification of Mr. Grey's experiment might concentrate the spark taken from the conductor, does not clearly appear. The mere insertion of a wire into a glass bottle, with- out water, or a metallic coating, as appears to have been the case in Von Kleist's experiment, would not certainly have accumulated the electric matter in quan- tity sufficient to communicate a shock : had the wire, however, rested in the phial in a compressed spiral form, and the hand covered the exterior surface, this effect would have been partially attained. During the interesting experiments, made J>y Mushenbroeck, and his coadjutors, Cuneus of Leyden was accidentally holding with one hand the glass bottle, containing water (which had been suspended to the conductor B 5 10 of the electrical machine), while the other was about to untie the wire of attachment, when he experienced that new and nondescript sensation, called the electric shock, as the consequence of introducing the animal frame into the circuit formed by conjoining the exter- nal and internal surfaces of a glass jar, supplied with an accumulation of electricity. The vessel thus em- ployed is called the Leyden Jar, from the birth-place of its discovery, and that of its discoverer. In consulting the historical records of this science, we find various exaggerated and romantic accounts of the effects of the electric shock, on the several in- dividuals who had the courage to try it. Though it is readily granted, that, in the infancy of so extraordinary a discovery, the timid mind might be severely wrought upon, and its fears and alarms be the fruitful parent of not only imaginary evils, but of physical injury, sub- ordinated as is the corporeal system to the fever of the mind ; yet much that is recorded must certainly be received " cum grano salis." Professor Winckler, having received the shock, informs us, seriatim, that it occasioned severe convulsions, he was afraid of an ardent fever, was necessitated to employ refri- gerating medicines, and bled at the nose : notwith- standing all this, Madame Winckler would hazard the dread experiment, the consequence of which was, that she could hardly walk afterwards, and, in compli- mental sympathy to her husband, also bled at the nose. Mushenbroeck received the shock from a thin glass bowl, and declared that he would not take another for the kingdom of France ; the Professor, however, appears to have been more frightened than hurt. Boze, to whom we have already alluded, on the other hand, expressed a wish to die by the electric shock, that his name might live immortalised in the annals 11 of the French Academy of Sciences: this was pitiful bravado, though Dr. Priestley thinks otherwise, and is pleased to call it " a truly philosophical heroism, worthy of the renowned Empedocles," whose brass slipper was found indigestible by the Cyclops of Etna, and ejected as a receipt for the body of the sui- cide : Mushenbroeck's timidity is certainly amusing enough, and Doze's affected courage truly French. No doubt the power of the electric shock on a feeble frame, or in some idiosyncrasy of its constitution, might be exceedingly injurious, and leave a permanent record of its power ; and a good deal, too, will depend on the way and manner in which it is given, together with the nature of that part of the animal frame which is submitted to its influence. Mr. Singer informs us, that he once accidentally received a considerable charge from a battery through the head ; the sens- ation, he adds, was that of a violent but universal blow, followed by a transient loss of memory, and indistinctness of vision ; and Mr. Morgan, in his pub- lished " Lectures," says, that if the diaphragm be made part of the circuit of a charge equal to two feet surface, the lungs make a violent effort, followed by a loud shout ; but if the charge be small, it never fails to produce a violent fit of laughter ; and adds, the comic powers of electricity are quite irresistible. On the other hand, a strong charge on this septum is not unfre- quently followed by some of the features of tragedy as sighs and tears, and even syncope. * About the * Though we are no friends to the fooleries of animal mag- netism, or the knavish tricks of mesmerism, it is a fact worthy of note, that, unless the medical electrician is sufficiently guarded, a partial transfer of the malady of the patient may be made to him; and this we have been assured has actually been the case, more than once, in the practice of a medical electrician. B 6 12 year 1747, Dr. Bevis coated a pane of glass on both sides with tinfoil, the principle of that called the " magic picture," and occasionally used to surprise by the shock it communicates. Subsequent to this period, Dr. Watson coated large glass jars with silver leaf; and the accumulated intensity was by these means so much increased, that wire was melted, and birds and fishes killed by the electric discharge. The French philosophers made many interesting experiments on a large scale : the shock was, in one instance, passed through a wire, extending about two and a half English miles, and it was discovered, that, as soon as the elec- tricity was withdrawn from the end of a wire 1319 feet long, it ceased simultaneously at the other. The Abbe Nollet, in the presence of the King of France, gave the electric shock to 180 of the French guards at the same time ; and, in another instance, the shock was passed through a line of Carthusian monks above a mile long, who were separated, the one from the other, by iron wires. On the 14th of August, 174-7, Dr. Watson made an experiment on Shooter's Hill, in which it was proved, that the electric matter occupied no sensible portion of time in traversing an extent of four English miles. The observers were supplied with accurate stop-watches, to note the instant they felt the shock, but the result proved that it was contemporaneous with the discharge.* This rapid movement of the electric power had suggested its application to the purpose of a telegraph, we believe, by Mr. Ronalds ; but recent experiments, made with reference to this question by Professor Barlow, have rendered it alto- gether equivocal. To those duly acquainted with the phenomena of electricity many counteracting agencies * This is not exactly the case. 13 may be naturally expected to disturb the equable and full transmission of the electric discharge; but it occurs to us, that if a copper wire (next to silver, the best conductor,) included in another as its shell or cear- ment, and this external hollow wire were coated with shell lac (the best insulator), the charge might be with- out difficulty conveyed with electric rapidity, to a far distant point, and thus become the prompt medium of intelligence, the number of consecutive discharges might be read off as the cipher of the telegraph, and the ends of the wires, namely, the transmitting and return wires, at the extremity of the distance passing through glass tubes filled with water, would concen- trate the intensity of electricity, and applied even to kindle gunpowder, might, by successive explosions, announce the intelligence. The electrical machine at the other end of the circuit would require to be simply turned by the winch, or put in motion by machinery, the Leyden jar being in close contact with the conductor, the upright, insulated, and self- acting electrometer attached to the plate machine would, at regular intervals, effect the discharge. Arago has proposed an electro-magnetic telegraph by conjoining these principles with the phenomena of electro-magnetism. Electricity might be also elegantly employed to light the gas jets used for street illu- mination ; a common stop-cock might allow the gas to flow simultaneously at each orifice, and 'by one electric discharge, the several jets, on the principle of Volta's inflammable air-lamp, would be instantly kindled, and the entire metropolis of London be illuminated with the rapidity of a flash of lightning. By the most accurate analogical reasoning, Dr. Frank- lin inferred the identity of lightning and electricity, the only inductive point that we can perceive in the u whole previous history of the science : this opinion was known to the world as well as the sound principle of reasoning on which that opinion was formed. The conjecture appears to have been verified in France, on the 10th of May, 1752, by Dalibard, Le Lor, Mazeas, Buffon, and Monnier : a bar of iron forty feet high, situated in a garden at Marly, was electrified by the transit of a stormy cloud over it, and by it phials were charged and other electrical phenomena exhi- bited. It was reserved, however, for Dr. Franklin to verify, altogether independent of this event, his own rich and inductive conclusions; believing that the cloud would consign its lightning to pointed conduc- tors, he had already waited a considerable time for the erection of a spire in Philadelphia ; in the mean time, however, it occurred to him that a common kite might afford a ready medium of access to the region of the storm. In June, 1752, a kite, with a pointed wire attached to its summit, was launched into the air, the kite was fastened to a key, by means of a hempen string, and the key attached to the earth by a cord of silk, concluding that this arrangement would facilitate its accumulation on the key, being insulated by the silken cord. According to the account which he has given us of the experiment, a considerable time had elapsed before the string of the kite afforded any signs of its having been electrified, and a promising cloud had already passed over it : his hopes had indeed begun to flag, when he observed some loose threads to stand erect, and be mutually repellent ; on this indication he presented his knuckle to the key, and the splendid dis- covery stood complete in all its form and character, and as soon as the string was moistened by the rain which fell, the sparks were copious: phials were charged at the key, and many of the experiments usually per- 15 formed by the electrical machine were repeated here. At the moment the electric spark glanced from the key, it is stated, the Doctor heaved a sigh ; his feelings may be faintly conceived, but to describe them were impossible : language is inadequate to pourtray the agitation of the mind, when eureka vibrates on the lip of the discoverer, and that discovery is fraught with some important relation to the economy of life, as was the case with the safety-lamp of Sir Humphry Davy : its great practical value consisted in the attach- ment of lightning-rods to buildings, to shield them from the stormy elements. By means of a pointed conductor the Doctor introduced the lightning into his dwelling, and a peal rung by it on two bells announced to our philosopher the apparatus charged by meteoric fire ; Dr. Franklin's daring experiment has no coun- terpart, save in the fire which Prometheus caught from the heavens on Elborus, amid the snowy range of the Caucasus. " Eripuit coelo fulmen." M. de Romas entwined a wire with the string of the kite he employed, and its size was seven and a half feet long, and three feet wide ; this wire renders the string a complete conductor, and fine, softened, copper wire serves very well. During dry weather we have always obtained, in any season, or at any period of the day, as much electricity as could be safely managed, and always preferred for the scene of experiment an ele- vated situation in the open country. It is dangerous to raise an electric kite during a thunder-storm ; and sufficient electricity can, under ordinary circumstances, be obtained from the atmosphere, without incurring any such hazard. On the 7th of June, 1753, about one o'clock p. M., when the elevation of the kite was 550 feet, and it had taken 780 feet of string, subtending an angle, with the horizon of about 45, M. de Romas 16 drew sparks from the conductor of the apparatus, a quarter of an inch thick, and three inches long, and the snapping was audible at 200 paces distant. On the 16th of August, 1756, the streams of electric fire were truly imposing, being apparently one inch thick, and ten feet long ; the report was equal to that of a pistol, and yet it was safely conducted by the string of the kite to the earth, by a conductor placed in its vicinity : experiments of this formidable description, however, are far too dangerous for repetition. To sum up all in this rapid glance, we perceive that the chief epochs in its history are, I. Discovery of the agent itself : II. The phenomena of attraction, &c.: III. Distinc- tion of electrics and non-electrics: IV. Accumulation of electricity : V. Identity of lightning and electricity ; and, VI. The practical application of conducting-rods. 17 CHAP. III. METEOROLOGICAL PHENOMENA SUBORDINATED TO AND DEPENDENT ON ATMOSPHERIC ELECTRICITY. - DIFFERENT ELECTRIC STATES OF THE ATMO- SPHERE. - AERIAL ELECTROSCOPES. E properly consider that the whole host of meteoro- logical phenomena is connected with electrical prin- ciples or modified by them. The dew that bathes the verdant carpet of the ground, and flickers in rain- bow imagery in the morning beam, the modification of the cloud from the cirrus to the nimbus and that nimbus charged with lightning and tempest deluging the plain or pelting the earth with hailstones or frag- ments of ice ; together with the meteors that flit and reel through the heavens, or traverse their surface in luminous lines ; or curtained in the sky, fan the air with films of diluted light including those very singular atmospheric precipitations called aerolites, all are either the creation of electricity or electricity itself. The experiments of Signor Beccaria, con- tinued with persevering assiduity for fifteen years, lead us to conclude that the air is almost constantly electric, that this electricity is usually positive, and relates to the amount of vapour it contains, while it is probable, according to Mr. Daniel, that the elasticity of vapour is increased when electrified. The passage of clouds over the electroscope frequently affect it, together with a current of air from the spot where clouds are forming or rain falling : with the exception of these, it should seem, that negative electricity is 18 rarely observed, and such may be called occasional or accidental circumstances : in cloudy weather weak positive electricity obtains, which changes to negative on the fall of rain, and when the rain ceases it returns to its primitive positive state. Positive electricity is weakest in the atmosphere during summer, and has its greatest intensity during winter: the usual positive electricity is weakest during night, increases with sun- rise, and decreases towards the middle of the day, increases afterwards as the sun declines, diminishes again, and during the night remains weak ; all these facts seem to prove that the electricity of the atmo- phere is influenced by the same causes which promote the equable distribution of moisture. It has been stated, that in clear weather the electricity is found in a positive character ; but this is disturbed by currents of air or the approach of clouds, especially when they hover near the apparatus, a fact particularly noticed in the vicinity of the Appenines, or other mountain ranges. In the precipitations of rain, hail, &c. the air will be found always negative, and the oscillations from positive to negative, and vice versa during a thunder storm, will be found exceedingly rapid. The question connected with the electric character of the atmo- sphere is one of intense interest; we are inclined to suspect that it is in the electric state of the air, as affected by moisture, in relation to the animal frame, that will be found the true solution of the effects of malaria ; modified, doubtless, by the morbid effluvia which exhale from stagnant marshes, &c. holding in solution decomposing animal and vegetable matter; while the lines of demarcation in typhus and inter- mittent fevers may have, often altogether independent of a local humidity, an electric relation to the rocky substrata of the spot itself. 19 We have not made electric experiments in fenny countries during autumn ; but at Orbitello and in the Pontine marshes in Italy, oar electroscope showed that the prevalent electricity was of a negative charac- ter ; and it is worthy of particular observation, that the air of rooms vitiated by respiration is constantly im- bued with negative electricity. Should a series of experiments, made with great care, and prosecuted with perseverance, prove that the electricity of the atmosphere is immediately connected with the morbid change of those peculiarly gifted localities, some modification of the paragrele, hereafter described, may effect a beneficial change. Typhus fever, &c., may be occasioned by a morbid current having the seeds of disease rankling in its veins ; wafted from the fens and marshes of Holland, modified, perhaps, by the super- marine atmosphere that it traverses on its passage hither, and determined in its rest, descent, and fix- ation to particular spots by an electric affinity; so that the soil of fairest and healthiest promise may be the seat of disease and the local residence of the destroyer : thus have we seen the shivering victim of intermittent disease even on the calcareous soil of Terracina. The late typhus fever that raged in Edinburgh was chiefly confined to one of the most open and best ventilated streets of the new town (King Street), where eighty cases, we believe, pre- vailed at once, and all among the superior classes of society. Thus, too, have we cast ourselves on the shores of the Mediterranean, in utter helplessness, suddenly smitten by a withering blast of the schirocco, wafted from the opposite coasts of Africa. Aerial electroscopes are instruments for determining the kind and quantity of atmospheric electricity; they differ from other electrometers (for the principle is 20 the same) only in possessing caps to preserve the insula- tion more completely, and having pointed rods attached to their summits : of these there are several varie- ties, as Volta's, De Luc's, Ronalds', Kinnersley's, and others : that which Mr. Ronalds employed to ascertain the kind of electricity on Mount Vesuvius was sup- plied with a pair of straws, in Volta's manner, instead of pith balls or slips of gold leaf, and it had a rod fourteen feet high. Mr. Kinnersley's electroscope consists of a hemispherical glass cap of about two inches in diameter narrow slips of tinfoil are attached on opposite sur- faces, within the instrument, and from the top, two minute pith balls are suspended by linen threads, the balls being parallel with the slips of tinfoil, a brass dome elevated about half an inch from the stem which enters the top of the' electroscope, and to which the pith balls are attached, serves to preserve the insula- tion by skreening the instrument from rain. A pro- longation of the brass rod at the stem, terminating in a fine point at an elevation of several feet, completes the instrument of Kinnersley; but having found Singer's beautiful modification of Mr. Bennet's gold leaf elec- trometer, with its double insulation, extremely delicate and sensible, we would propose a modification of it for the purposes of an aerial electroscope. A second glass tube of minute diameter, entering into the insu- lated one already employed, might be supplied with a thread of copper wire passing through its centre, ter- minating above in a lengthened and finely pointed brass rod, and connected below with the slips of gold leaf the instrument should also be supplied with a protect- ing cap or dome. By this means the slips would be additionally insulated, and rendered still more sensible ; and if two concentric cylinders of glass were used for the body of the instrument, it might be improved. 21 The only additional apparatus required to ascertain the kind of electricity manifested is merely a stick of sealing-wax. When the pith balls or gold leaves separate or diverge, by having acquired electricity under any circumstances in which they may be placed, all that is necessary to be done is merely to rub the wax gently on a piece of flannel, or simply on the sleeve of the coat, and approach the instrument gradu- ally with it. If the pith balls or the metallic slips cfose or collapse, the electricity is positive ; but if they, on the other hand, expand farther, the manifested elec- tricity is negative. 22 CHAP. IV. HEAT AND MOISTURE, THEIR RELATIONS TO AERIAL ELECTRICITY. DE LUC's ELECTRIC COLUMN. ITS APPLICATION TO CHRONOMETRY. CANTON'S BELLS. BY a statical law heated air ascends, and its place is supplied by colder and, of course, denser air, and currents of air will be formed and move in the direction of the source of heat and rarified medium : the heated air of the tropical regions ascends, and the colder air of the arctic and antarctic poles will press forward to the equator, and thus tend to equalise the temperature of the earth ; disturbing effects, however, will arise from local causes by which modifications will accrue in this equable distribution of heat, and when there arises an unequal distribution of temperature there will also exist an electric excitement. The superior tem- perature of the equatorial regions arises from the direct and unlimited impression of the vertical rays of the sun, while on other parts of the terrestrial surface these rays will strike more or less obliquely, and will thus be attenuated in the ratio of that obliquity. Change of volume is a source of heat or cold ; air being attenuated, caloric is absorbed, while heat evolves on the density of air being increased: even during the formation of dew, heat is evolved, cold being a pre- vious occurrence ; and when water passes into the solid form of ice, heat is, in like manner^ disengaged, the cooling process being a previous and independent cir- cumstance : thus, too, when elastic vapour condenses .v 23 in the cloud, heat is a natural and necessary conse- quence of that condensation, and the denser the cloud the higher will be the temperature at the moment of its formation. These are some of the sources of heat ; and that greater abundance which we receive in a robe of light by day, finds a compensation again in the heat that radiates to the heavens from the surface of the earth in a clear and brilliant nocturnal sky : clouds check by their occasional interference this radiation, and prevent the consequences which might ensue from that power being unrestrained and unfettered. By the process of evaporation aqueous vapour is constantly rising into the atmosphere, and when a maximum density is formed there will of necessity be a precipita- tion of moisture a change of temperature may also effect this purpose : now, moisture will serve as a con- ducting medium for the atmospheric electricity, and also diffuse or carry it away ; while, therefore, the evolution of heat will tend to raise the electric charac- ter of the air, that of moisture will subserve to its dis- charge. Those collections of vapour, called clouds, are always electrical : they may indeed be considered as composed of particles of aqueous vapour aggregated by electricity ; and summer showers of rain are often invested with high positive electricity. The experi- ments of Mr. Bennet and others clearly prove, that in evaporation and other natural processes connected with hygrometric changes generally, electricity is super- induced. In truth, all atmospheric mutations and phe- nomena are intimately connected with electrical action : the changes that are rung in the superior regions of the sky, and the products of which salute our earth, are determined or modified by the diffusion of heat and moisture in the atmosphere. M. de Luc's electric column is composed of circu- lar slips of silver foil and zinc forming binary groups ; these are enclosed in a tube of glass, and are pressed together by a screw at each end. When this tube is placed horizontally on a stand, and the metallic ter- minations come into contact with a gold-leaf electro- scope placed at each end, the leaves diverge ; the one connected with the silver termination of the column will evince negative electricity, and that in contact with the other end will be found positively electric. When two of these columns are mounted in a vertical position on insulated bells, with a metallic bar connecting them at top, a continued chime may be obtained by attach- ing a small metallic ball to the apparatus : this ball is suspended by a silk thread from the cross bar at top, and vibrating between the two bells to complete the circuit of the electric movement, an uninterrupted chime may be preserved, and has indeed been con- tinued without interruption for several years. Atmo- spheric air alone is necessary for its movements ; but these oscillations are unsteady, and must be subject to variations in the moisture, temperature, and density of the atmosphere. In 1803, Messrs. Desormes and Hatchett first attempted to construct a dry electric column ; but it does not appear that they succeeded ; and M. de Luc's column, in 1809, was the first suc- cessful effort. Signer Zamboni's column was intro- duced in the same year, and by means of it he endea- voured to establish a perpetuum mobile. There are in this construction two electric columns formed of gilt paper sprinkled with peroxyde of manganese : the piles, as in the other case, are vertical, and distant about six inches from one another. Each pillar is sur- mounted by a brass ball, and a fine steel needle is made to move on a fulcrum ; the longer arm of the lever being alternately attracted by each of the balls and 25 repelled to the other, thus oscillates between them. D/. Schiibler of Hofwyl has proved that its move- ments are not connected with the electric state of the atmosphere, the principle of excitement being within itself. Heinrich, Singer, and Grindel, however, have incontestably shown that its movements are unsteady and unequal, being subject to variable temperature and moisture. This elegant machine has even been employed, both in this country and in Germany as a prime mover to clock-work, in the measurement of time. Mr. Ronalds of London has so applied it ; but its oscillations being unequal, its chronometry must be also subject to variation. In some experiments on electricity Mr. Canton ingeniously employed three small bells to announce to him when his conductor was electrified : a metallic cap was attached to the rod to preserve its insulation, and such an apparatus is commonly used in electrical experiments. This simple chime consists of a metallic bar, which is connected by means of a hook with the conductor of the electrical machine ; three bells are suspended from this bar, the two extreme ones being attached by means of a metal- lic chain, and the central one by a cord of silk. A metallic chain again connects the central bell with the earth, and in the space on each side between this bell and the others hangs a small metallic ball by a silk thread ; this ball incessantly vibrates between the bells at each end and that in the centre, imparting to it the electricity which has descended by the metallic chains to the bells at either end, the chain attached to the central one serving to convey it finally to the earth. We remember to have seen one of these chimes erected over a gateway, and attached to a lightning conductor, in the neighbourhood of Zug, capital of the Canton, and another in a garden on the route from Zurich to c Basle on the Rhine. These chimes might be attached to the Paragreles on gentlemen's pleasure grounds, and thus become a curious and interesting appendage, while they would announce by their peal the electri- city of the atmosphere on the approach of the storm cloud. CHAP. V. LIGHTNING IDENTIFIED WITH ELECTRICITY. ME- TEORIC PHENOMENA. BOLIDES. ST. ELMO'S LIGHT. AURORA BOREALIS. METEORIC STONES. ELEC- TRICITY OF VOLCANOES: JLHERE cannot be a fact more incontestibly proved than the identity of lightning and electricity : when an electrical battery is discharged, the flash and sound have a striking analogy with the lightning and the thunder. The experiments made by Dr. Franklin, and in the garden at Marly, have been already referred to, and the fact, that every experiment made by means of the electrical machine maybe repeated with the light- ning brought down by the electric kite, completes the chain of evidence. It has already been stated, that in repeating experiments on atmospheric electricity, con- siderable caution will be necessary, especially during a thunder storm ; and if on approaching the insulated string of the kite there is a sensation on the skin like that of cobwebs, it will be well to abandon the kite to its fate. Professor Richman of St. Petersburgh fell a victim to an experiment of this kind by incautiously inviting the lightning collected by a kite into his house. It appears that he had erected a conductor, and arranged a considerable apparatus for the purpose of collecting the aerial electricity. On the 6th of August, 1753, during a thunder storm, he and his friend Mr. Sokalow, engraver to the Royal Academy, were standing by the apparatus, and it would seem that Professor Richman had approached too near; for c 2 28 at this precise moment a flash of lightning from the conductor laid him prostrate at the feet of his friend. The survivor describes the explosion which attended the awful catastrophe to have been exceeding loud, and the apparent vivid condensed ball of electric matter which struck Professor Richman at a foot distance appeared to be several inches in diameter; the metallic rod was shivered to pieces, and the dis- persed fragments left the mark of their form and dimensions on the clothes of Sokalow. Professor Richman had seventy rubles of silver in his pocket, which were not injured, but a clock that stood near was stopped, the door of the room broken, and the ashes of the hearth dispersed. There are several luminous appearances occasionally seen in our atmosphere, which have very properly been ascribed to electric phenomena, such as bolides, or fire balls shooting stars those phosphoric lights that flicker on the masts of ships at sea the aurora borealis, and others of a similar description. Bolides, or fire balls, and shooting stars, have been ascribed to solid ignited matter, quenched by falling into the lower and humid stratum of the atmosphere : if a considerable electric discharge be passed through an exhausted receiver, it assumes the straightness and brilliancy of a falling star: shooting stars occur in such periods as are known to be most acted on by electric changes : they are prevalent in clear frosty weather, and when dry easterly winds and a brilliant nocturnal sky obtain ; also, in the intervals of showery weather, and on summer evenings when well defined clouds are observed to move in a clear atmosphere. Sometimes these meteors are possessed of beautifully coloured light, and their scintillations are very vivid: prismatic tints were observed in the scintillations which 29 were thrown off from the great meteor of 1783; and from the bluish light shed by it, the moon at Brussels appeared to be red : during a thunder storm fire balls are frequently observed to descend, and we must sup- pose them ascribable to the same cause. According to the observations of Professor Brandes of Breslaw, falling stars move in all directions relative to a vertical line ; the number which approach the earth are greater than those which move from it ; and though these have undoubtedly a real velocity, it would appear that much of their apparent one is a mere illusion, dependent on the motion of the earth. AH Bey mentions a beau- tiful meteor he witnessed near Bethlehem : "I saw appear, under the form of a star, two or three times as large and much more luminous than Jupiter or Venus in their greatest splendour, a meteor, which unfolded to the eastward a tail that appeared to me to be about two feet in length ; meantime the meteor advanced toward the west, gently waving its tail in a horizontal direction, at an altitude of nearly SO 71 , or about that of the sun and moon. In the tail, which afterwards divided into several rays, were united all the colours of the rainbow in its greatest beauty." * Falling stars are generally seen at night: we have, however, at least one well attested fact, of a falling star having been seen by Hansteen, at mid-day : on the 13th August, 1823, at a quarter past eleven o'clock A. M., it passed through the field of his teles- cope in about a second, and resembled very much the unequal and somewhat serpentine motion of an ascend- ing rocket. The fall of shooting stars has been mentioned as sometimes witnessed: thus it is stated that in the * Travels of All Bey, in 2 vols. 4to. London, 1816, vol. i. p. 231. c 3 so night preceding the battle of Brandywine, the sentinel saw a shooting star fall within a few yards of the spot where he then stood : on examining the place, he found a sparkling gelatinous mass : a similar phenomenon occurred near to General Griswold : in this case it fell on a mass of ice. These and others of a similar kind appear to be the Tremella meteorica. Much uncertainty is connected with our opinions on these meteoric phenomena : that they are electric seems undoubted, but some contend that they come from beyond the boundaries of the atmosphere ; there appears, however, to be no authentic warrant for such eccentric speculations. There are a great variety of kindred phenomena of an electric character, such as those flitting lambent flames that are observed to dance over still collections of water, called ignesfatui, which have indeed been supposed to be phosphoretted hydrogene ; but to our vision the phenomenon is alto- gether different, and we believe dependent on electri- city for its existence. * Those peculiar luminous * During the month of July last we had the pleasure of wit- nessing this very curious phenomenon, in the marshy grounds between Hertford and Stevenage, when on the mail, coming from London northward. The day had been dense and sultry, and toward evening a stratum of vapour hovered over the marshes of the valley. On the right two ignesjatui started up suddenly, and at some distance apart ; the appearance was altogether that of a solid ignited nucleus, diffusing brilliant radii around it. Their locality, as far as could be determined, seemed to be clumps of rushes. At one period there appeared to be a flitting flickering motion, somewhat resembling that of a hovering insect ; but this was not continued. The phenomenon lasted several minutes, and both were suddenly extinguished, the one after the other. It seemed to us difficult to conceive of electricity being presented under the attendant phenomena with which these were accompanied, and the entire features were more analogous to those of an insect power- 31 phenomena which have been seen on the masts of ships at sea, and termed by foreigners, Castor and Pollux, St. Elmo's light, St. Barbe, &c. are akin to the diffuse and lambent electric light which is occasionally seen in stormy nights during the prevalence of rain, to fret the horse's mane, or attach itself to the tips of the umbrella, or the edge of the hat. Falconer thus notices the phenomenon : " High on the masts, with pale and vivid rays, Amid the gloom portentous meteors blaze ;" and the Baron de Humboldt also describes it: "On observing the appearance of the masts, the maintop- gallant-mast head, from the truck for three feet down, was perfectly enveloped in a cold blaze of pale phos- phorus-looking light, completely embracing the circum- ference of the mast, and attended with a flitting or creeping motion, as exemplified experimentally by the application of common phosphorus upon a board, and the fore and mizen top-gallant-mast heads exhibited a similar appearance in a relative degree. This curious illumination continued with undiminished intensity for fully illuminated; but whether some insect allied to the tribe termed Gryllus gryllotalpa, or mole cricket, has the power, under peculiar circumstances, as the Rev. Dr. Sutton has conjectured, of evolving light, seems not altogether determined: this phe- nomenon might be adduced to plead in its favour, thus the scolopendra electrica is only occasionally luminous, and when excited. We find that a gentleman observed a similar pheno- menon to that described, in low marshy ground, after a sultry day and a dense evening fog; it had also to his vision all the appearance of a solid ignited body. We have also witnessed a lambent flame gliding on the surface of a stagnant lake, but are of opinion this last is altogether distinct from the other, and depends on different principles. C 4f 32 eight or ten minutes, when becoming gradually fainter and less extensive, it finally disappeared after a dura- tion of not less than half an hour." A writer in Mr. Lou- don's Magazine of Natural History (vol. i. p. 304.) states that " two of these phenomena made their appear- ance on the evening of the 26th of October, 1823, on board the Sandwich Packet, on the voyage from the West Indies to England, when about 200 miles north of the Bahamas, and remained, one at the spindle of each mast-head, for about two hours ; the atmosphere being in a very unsettled state with rain and lightning. The one at the mainmast head was rather brighter than the other, and before disappearing occasionally passed up and down the upper part of the mast, but never en- tirely disengaging itself notwithstanding the heaving motion of the vessel." This is evidently an electric phenomenon, and the same with that described by Humboldt; but there is another phenomenon which may be confounded with it, though clearly referable to a different cause ; namely, luminous marine mol- luscs, and which Mr. Thompson, in his Zoological Re- searches, No. II., describes as making its appearance during violent storms in a luminous patch or ring upon the masts and windward yard-arms. It cannot be doubted, that the sea spray in storms would carry aloft these luminous insects which the storm kindles into peculiar brilliancy, just as we have in lesser storms seen the deck and lower part of the mast illuminated by the waves breaking over the ship. Electric stars or gleams have been seen to rest on the summits of spires and conducting-rods on land : the lambent lights which are seen among the lofty range of the Himala chain, as well as the Cordilleras of the American Andes, may be also assumed to be electric fire : lumi- nous spots, we presume also of an electric character, 33 have been sometimes noticed in the air near the hori- zon, and appear occasionally very bright in Ohio, in the United States of America. Dr. Franklin considered the coruscations of the aurora borealis as the effects of a continued but slow discharge of the atmospheric electricity, surrounding the poles into the air above them. It may be con- sidered as an electro-magnetic phenomenon, and the recent discoveries in that interesting branch of science seem to validate the position. The aurora may, there- fore, be considered as an electric curtain, let down from the heavens in polar latitudes, and affected by the magnetic polarity of these regions : when a stream of electricity pervades the vacuum produced by an air- pump, its dilute and diffuse light very much resembles the aurora borealis ; the same variety of colour and intensity obtain in both, with the same coruscations and undulations the streams also show that diversity of colour and character, now minutely ramifying and again beaming forth and glowing in one diffuse stream of dilute light : it has therefore been inferred, that this curious and beautiful phenomenon is entirely referable to electricity passing through the superior regions of the atmosphere, where that medium must needs be exceedingly attenuated. Their altitude has been va- riously estimated : the Honourable Henry Caven- dish makes it 71 miles, Boscovich 825 miles, Bergman 468 miles, Euler extends it to thousands of miles, Mairan to 200 leagues, and Messrs. Dalton and Cros- thwaite to 150 miles. Judging from these eccentric deductions, it seems clear that there must be some common and strange error in the estimate *, and alto gether very questionable whether one of the entire * Perhaps connected with some of the phenomena of refraction, c 5 34 number be a correct deduction : in the north-eastern parts of Siberia, the loud hissing noise which accom- panies their appearance so terrifies the dogs that accompany the hunters, that they will not move till the noise is over : Mr. Nairne and Mr. Cavallo have each acknowledged to have heard the sound that sometimes accompanies the exhibition in these latitudes, though it must be admitted that much scepticism has been entertained on this point ; the fact, however, we think undoubted, and can remember, in our boyish days, to have heard this sound most distinctly, while numbers in Scotland can attest the same thing a species of fanning sound, like a thin curtain waving in the breeze. Now this simple fact proves that the calculations concerning the height of the aurora bo- realis are founded in error, because, even at the lowest computation, that of Mr. Cavendish, the tenuity of the atmosphere at the altitude of 70 miles is beyond the rarefaction of the best air-pump ever constructed, and in such a medium all sound must necessarily be extin- guished : even Mr. Dalton has altered his estimate, for he calculates the height of the aurora of 29th March, 1826, which appears to have been immediately over the towns of Kendal and Kirby- Stephen, at one hun- dred miles, the breadth of the arch at eight or nine miles, and its visible length from any one place 550 miles. In the Shetlands, the aurora borealis is called " the merry dancers," dimly seen immediately above the horizon after twilight, and the streams beaming with refulgent light assume various forms and shades of colour, frequently forming a diffused sheet over the visible hemisphere, exhibiting a spectacle of much grandeur : in Hudson's Bay they are said to equal, in effulgence, a full moon, and in Lapland and Sweden to enliven and illuminate the path of the traveller. In 35 north-eastern Siberia their splendour is orientally mag- nificent, moving with incredible velocity, and clothing the sky with inimitable brightness, " resembling a vast expanded tent, glittering with gold, rubies, and sap- phires." Dr. Halley has ascribed their production to the same cause as that effective in magnetism; and Mr. Dalton's observations seem to prove that the di- rection of the beams of the aurora borealis is really that of the dipping needle : Signer Beccaria con- sidered the phenomena of magnetism the result of a constant natural circulation of electricity from north to south, originating from several sources in the northern hemisphere : the aberration of the common centre of these currentFIrohTtHe north point, he supn posed to be the cause of the variation of the mag- netic needle, the term of this declination from the centre, the period of the variation ; and the obliquity of the currents the cause of the dip of the needle : the stars are often seen through the electric curtain of the aurora borealis ; in equatorial regions this beautiful phenomenon is rare, but in polar regions it is not unfrequent. There is not, among the entire phalanx logical phenomena, a more extraordinary circumstance than those marvellous precipitations from the atmo- sphere, called meteoric stones, a question, however, it must be acknowledged, which, though fraught with interest of a peculiar kind, is yet one perplexed with difficulty and intricacy. That our earth has been, from the earliest period of the history of man, visited by stony showers, is a well accredited fact, nor does there exist, in the wide extended circle of our philosophy, a phenomenon better established. Sacred and profane history unite their voice in proclaiming this truth to the world; and the legends of the East, with the c 6 36 annals of Greece and Rome, all attest the fact ; and after making every allowance for their fictions and their fables, their allegories^ and their orientalisms, the nuclei present the Teatures of truth ; indeed none would now be entitled to the name and epithet of a philosopher, who should presume to question these curious realities. Modern times have added numbers to their muster roll, and the catalogue is now exten- sive and complete : the first recorded fact of this kind is that which we find in the 10th chapter of the book of Joshua*, which destroyed the enemies of that celebrated leader in the way going down to Bethoron. The " stones of darkness" f may also be of this description, admirably illustrative of their appearance, the " colore adusto" of Pliny. Yet how shall we interrogate these exotic beings " What are these, that look not like the inhabitants o' th' earth, And yet are on't ? Are ye aught that man may question?" Wherever they have fallen, whether in mtertropical climes or polar regions, they possess a similar cha- racter, and one so well marked as to stamp them pe- culiar once seen, they are easily recognised, and the specimens that remain in the British Musuem, and in collections on the Continent, as well as in pri- vate cabinets, establish the position. We find attest- ations of these stony showers, as has been stated, to whatever side we turn in the volume of sacred story, or the profane page ; and are of opinion that what is recorded in the " Acts of the Apostles J," owned a similar origin. The expression is remarkable "a * Joshua, x. 11. f Job, xxviii. 3. J Acts, xix. 35. 37 worshipper of the great goddess Diana, and of that which fell down from Jupiter." It is true the image is introduced, but this is not in the original, our trans- lators having supplied the words put in italics. * Of this description, too, may have been the stones wor- shipped by the Egyptians : such a stony mass was, according to Tacitus, worshipped in Cyprus ; and, agreeable to Herodian, the Phoenicians had an idol of a similar kind the stone was conical in form, of a. black colour, and reported to have fallen from heaven ; and, from the description that Ali Bey has given us of the black stone in the temple of Mahomet, at Mecca, it may have had a meteoric origin. It is called Hhajera el assoudd, or heavenly stone, and is stated to have fallen at the foot of the mountain called Djebel Koubiis: an interesting list of meteoric stones will be found in a work entitled " Delia caduta di un Sasso dal aria ragionamento" published at Modena, in 1766, by Do- menico Troili. Livy describes a fall of stones on Mount Alba, in the reign of Tullus Hostilius, about 652 A. c. ; the Senate doubted the reported fact, but enquiry verified the circumstance ; it is thus mentioned : " Haud aliter quam quum grandinem venti glomeratam in terras agunt, crebri cecidere coelo lapides." Plutarch -j- mentions a stone which fell in Thrace, at Egospotamus, which Anaxagoras supposed came from the sun, and it seems to have been of considerable size " mag- nitudine vehis :'' the person who saw it descend described the phenomenon thus : "It hovered about * Bloom field's Recensio Synoptica Annotationis Sacrae, in loc. thus : " Sometimes I am inclined to believe the material of the image might have fallen from the skies. " f In Vita Lysandri. 38 for a long time ; seemed to throw out splinters, which flew about like wandering stars before they fell ; and at last it cast down to the earth a stone of extraordi- nary size." Pliny, who saw this stone, informs us that it was of a dark ournt colour: he mentions another which fell at Abydos, and was there wor- shipped ; and likewise one in Potidaea. Gassendi saw, on the 27th of November, 1629, in a clear sky, a burning stone, about four feet diameter, fall on Mount Vaisir, between the towns of Guillaumes and Perne in Pro- vence ; it weighed 59 Ibs. ; the fall was accompanied with a noise like many cannon, and surrounded by a luminous circle, coloured like the rainbow. In 1510, no less than 1200 fell in a field near the river Abdua; one weighed about 120 Ibs., and several exceeded 60lbs. Soldani gives us an interesting account of a fall of stones in Italy, on the 17th of June, 1794: " A tre- mendous cloud was seen in Tuscany, near Sienna and Radicofani, coming from the north, about seven o'clock in the evening, and sending forth sparks like rockets throwing out smoke like a furnace, and rendering violent explosions and blasts more like those of cannon and numerous muskets than thunder and casting down to the ground hot stones, while the lightning that issued from the cloud was remarkably red, and moved with less velocity than usual; the cloud ap- peared of different shapes to persons in different situ- ations, and remained suspended a long time, but every where was plainly seen to be burning, and smoking like a furnace. Its original height, from a variety of circumstances, seems to have been about the common region of the clouds." * A shower of stones fell at L'Aigle, in Normandy, on the 26th of April, 1803, and amounted to nearly SOOO in number: the phenomenon * " Remarks concerning Stones," &c. E. King, 4to. ] 796. p. 4. 39 was witnessed by several persons, and of these we possess in our cabinet several entire specimens, and fragments of others. In July, 1810, a great stone fell at Shahabad, in India, the fragments of which killed many persons, and, it is recorded also, burnt five villages : a meteoric stone fell in u field near to Major Topham's house, in Yorkshire, and a boy witnessed the fall. On the 9th and 10th of September, 1813, several stones fell at Limerick, in Ireland : and on the 13th of November, 1822, a meteoric stone fell atEpinal, in France ; its size was equal to that of a six-pounder. On the 13th of February last, at half past 7 P M., a meteoric stone fell at Launton, near Bicester. The explosion which attended its fall was compared to the discharge of a triple barrelled gun, there being three distinct yet rapidly successive reports : the stone penetrated the ground to the depth of about a foot, and its descent was distinctly witnessed by a labourer in the employment of Mr. Cross. It weighed about 2 Ibs., and a fragment is in possession of a medical gentleman at Buckingham : the explosive report was distinctly heard four miles from the spot where the meteor fell. The most curious recorded fact of this kind, as it relates to the death of an individual by an aerolite, is described by Signer Angelo Bellani of Pavia, in the Giornale di Fisica e Chimica ; and de- scribed as " one of those stones projected from the clouds, which struck with sudden death a Franciscan friar of Santa Maria della Pace, at Milan, and which is open to the inspection of every body, in our mu- seum." This is extracted from a work printed at Tortona, in 1677. The remaining monks of the con- vent, together with the Canon Manfredo Settala, having examined the body, discovered a wound, and probing it, found the fragment of a meteorolite, which 40 seems to have penetrated to the bone : it weighed about a quarter of an ounce, and was not perfectly round, but rather obtuse angled ; its colour somewhat resembled a burnt brick on one part, and on the other, seemed to be covered with a thin ferruginous crust; when it was broken, it emitted the smell of sulphur. Without particularising those meteoric stones, which have fallen within these few years, as at Juvenas (of which we possess a fragment of considerable size), &c. we may state generally that the British islands have several times been the scenes of these extraordinary visitations, including the metropolis of the British empire ; for an aerolite fell in London, on the 18th of May, 1680. The spongy masses of iron, as that in Siberia, described by Pallas, and in many other parts of the world, are presumed to possess a similar celes- tial birth : like aerolites they contain nickel; and the spongy iron is quite malleable, and capable of exten- sion under the hammeT. Mr. Sowerby presented a sword to the late Emperor Alexander made from meteoric iron in his cabinet; and the Esquimaux knives, brought from the arctic regions by Captain Ross, were found to be meteoric iron, and contained nickel : some of these are in the British Museum. The most prevalent opinion about meteoric stones is, that they come from the moon a view once stoutly advocated by Laplace ; but as the moon became too familiar an object, he at length brought them from regions beyond the boundary of our solar system, as circumscribed by the path of Uranus a point from whence even telescopic vision recoils : we are inclined to reject this erratic opinion, and are as little disposed to give credence to the hypothesis which would regard them as mere chips or splinters thrown off from those lesser planets, sometimes called asteroids, which move 4] between the orbits of Mars and Jupiter, and have ! received the names of Ceres, Pallas, Vesta, and Juno ; and though their ellipticity is more "eccentric than that of the other planets, we do not see how it can affect the question : in like manner we feel equally disinclined to believe that there is a zone of aerolites whirling round our " nether orb," that are somehow occasionally brought within the attractive sphere of the earth ; an opinion, if we mistake not, that owns Dr. Brewster for its author. There might be some colour for all this speculation, were these aerolites unattended with extraneous paraphernalia mere stones descending through the atmosphere ; but we cannot forget that clouds and darkness, lightning, and all its accompaniments of coruscations and deto- nations, attend their descent : it seems foreign to all analogy to presume that their mere passage through the air is sufficient to kindle up the elements of light- ning into a storm ; and with respect to the moon, nothing can be collected from thence to give colour to the supposition : we have unweariedly swept the lunar surface with excellent and powerful dioptric and re- flecting telescopes, and are just as ignorant of the true nature of th'e lunar disc as before we began the investigation. There are some who would have us to believe that those silver annuli that seem to float in the abyss of space, and which, when the moon is in quadrature, are thrown into such sublime rilievo, are volcanic craters ; but all this is mere conjecture, hav- ing no solid basis to rest upon ; and as for the light observed on the lunar disc by Sir W. Herschell, Capt. Kater, and others *, it may, if we do not greatly mistake, be always seen when the moon is two or * And we believe, also with the unaided sight, by the Rev. Fearon Fellows, at the Cape of Good Hope. 42 three days old. If we remember right, it has been recorded by Hevelius, and may find an analogy in the periodic gleams which flash amid the Himala range, and seem to be electrical, or of some phosphorescent description. The phenomena of the occultation of the stars by the moon, and of the emersion of Aldebaran lately described by Mr. Bonycastle, are antagonist to the existence of a lunar atmosphere, a condition necessary to the material ignition of a volcano, though, chemically speaking, sudden and energetic combina- tions manifest sometimes the phenomena of ignition and combustion : we speak, however, generally in this case. Mr. Howard tells us that the survey of the moon's disc presents to his view the miniature of an icy scene. He considers that the lunar surface has a chilling in- fluence on that part of the earth which is opposed to its influence, that is to say, the latter radiates more than the former gives in return; and that much of what have been called seas are shelled with ice. Our own inferences, from the vision of that satellite through the telescope, are quite in harmony with Mr. Howard's view : much that we perceive are immense and ex- tensive glaciers and alpine ranges sheeted with snows ; and if there indeed be volcanoes in the moon, the annuli we perceive may be the lips or edges of lunar Heclas. In these assumptions one difficulty succeeds another in rapid succession ; for after having supposed the ex- istence of such volcanoes, we have also to impart to them a projectile force which exceeds our belief: the meteor must set off with a velocity of 6000 feet in a second of time, three times that of a cannon ball, and it would enter our atmosphere, moving at the rate of 25,000 feet in a second ; now the calm manner in which these aerial beings salute our earth is incom- 43 patible with such an opinion ; and after this double petitio principii has been granted, they should be con- fined to specific latitudes, while there is no latitude from the arctic to the antarctic pole, unhonoured by the celestial descent. We have them in our keeping to tell us " what stuff they're made of," and ought diligently to interrogate them, that we may learn what account they give of themselves : they are known to yield, under chemical analysis, iron, nickel, and chro- mium, and sometimes calcareous and other earthy and combustible matter: now it ought never to be over- looked in this estimate, that all these are found in- digenous to our earth ; the proportionals vary, it is granted, from any other mineral mass yet discovered among the rocky features of the globe, but then, at- mospherical electricity can ring a new change, or introduce a note unknown to terrestrial minerals. Electricity can suspend or unhinge the affinities con- sidered natural to bodies, or- impart an entirely new one ; thus easily may combining proportionals be changed, and another order in relation to their consti- tuents be introduced. No new material has ever been discovered in them merely such as are common to our globe, and familiar to us, and the fact that they all possess the same relation of parts proves not only a common source, but a common agent in their production ; now the productions of terrestrial volcanoes vary ex- ceedingly, while these have the same character, and the slight shade of difference in some is scarcely per- ceptible ; " non omnibus facies una, nee diversa tamen." All that we require are vehicles to cha- , rioteer their constituents aloft and these are numer- ous ; winds (the whirlwind and the tornado), gaseous media, specifically lighter than air, as hydrogen and its compounds ; evaporation ; or even atmospheric 44 air when expanded by heat, and the elasticity of which is increased by the vapour it may contain ; volcanic eruptions, too, may toss their dust into the air, and that to an immense elevation, as has been shown by Mr- Poulet Scrope in reference to the enormous altitude to which ashes and fragments of stones were launched in a recent eruption of Vesuvius, that of November, 1822. Fine sand wafted by the wind from the coast of Africa fell on a ship 600 miles distant at sea ; and we possess a quantity of finely divided volcanic dust, projected from the volcano of St. Vincent, and collected from the deck of a ship three hundred miles from that island. In some of these eruptions, the finely divided volcanic matter was raised above the lower atmo- spheric current, and carried, contrary to the direction of the wind, to Barbadoes. Some time ago, we analysed a liquid collected in the crater of a volcano in one of the Lipari islands, presented by Lord Mountnorris, and found in it iron, nickel, and the usual consti- tuents of meteorolites. The fall of meteoric stones at Radicofani, in Tuscany, took place the very day after the great eruption of Vesuvius, which over- whelmed Torre del Greco: that of Epinal was imme- diately after an eruption of the same volcano ; and many more instances might be adduced to prove, that such remarkable concretions are precipitated when the atmosphere must necessarily be loaded with volcanic matter. The atmosphere becomes, as it were, to speak chemically, saturated with metallic matter and earthy particles ejected from volcanoes, or carried up by evaporation or other causes, and these will necessarily be diffused over an immense surface where they float in the superior regions of the air, till the lightning darts through them, carrying, like a ploughshare, accumulated matter in its progress, and, by the power- 45 ful electrical attraction thus excited, these particles will be instantaneously drawn into the vortex of the lightning ; for this lightning finally encountering an electricity of an opposite kind, an explosion ensues, the collected mass is fused and agglutinated, and the meteorolite thus formed tumbles to the ground ; and it may also be very easily supposed that immense tracts of earthy matter, and metallic oxydes imbued with their peculiar electricity, might encounter in their progress metallic, carbonaceous, or other inflammable matter, also scattered over an extensive region ; now the last would be naturally invested with the opposite electricity : such a conflict would be terrible, and evolve the splendours that shroud the sublime phenomenon. The electric fire would kindle the gaseous media, and the result would give rise to aqueous vapour, while the explosive electricity would instantaneously fuse the included materials, and as immediately collapse into the focus where the opposite electricity was condensed : the crust of meteoric stones seems plainly to indicate that they have traversed an aqueous medium, such as this supposes. We therefore do not see the necessity for consider- ing meteoric stones extra atmospheric, simply, because we possess all the conditions necessary for their pro- duction vehicles sufficiently active and extensive to carry aloft the materiel, and an agent powerful enough to alter the arrangement of their constituents, and fuse them into a solid mass : on any other view of their production all is gratuitous assumption ; the elements of doubt enter into its composition, and we perceive nothing solid or satisfactory. We cannot doubt that the power of lightning is sufficient ; those extra- ordinary productions, the sand tubes or ceraunian scinter, found in Germany, and particularly at Drigg, 46 in Cumberland, fine specimens of which we received from the late Mr. Irton of Irton Hall amply attest the intensity of this power ; and, if we are not misinformed, recent evidence of their formation has been presented on the Continent. One of these tubes finely glazed and enamelled by lightning penetrated to the depth of nearly thirty feet, exclusive of what might be called its root : we have also a specimen of fused amphibole from the summit of Mont Blanc. When a chip of meteoric stone is submitted to the jet flame of the compound gas blowpipe, as we have' observed, it is fused into a magnetic bead: this we found in frag- ments taken from specimens of the meteoric stones of L'Aigle, Juvenas, &c. in our cabinet. If other evidence were wanted for the completion of our conclusions, we think it completely supplied in the phenomena at- tendant on the fall of the meteoric stones which took place in the commune of Le BafFe, department des Vosges, on the 13th of September, 1822, as described in the Annales de Chimie, and attested by Nicholas Etienne, the mayor of BafFe. A violent thunder storm commenced about four o'clock A.M., the air being quiet, and the sky filled with electric clouds : the lightning was intense, and abundant, and frequently directed to the ground : the thunder was loud and sharp. At seven A. M. the storm was over Baffe, when the inhabitants suddenly heard a noise, quite distinct, like that of a carriage dragged with violence over a rough road : its duration was full seven minutes, and its intensity at last frightful finally, a dull explosion was heard, when the meteor struck the ground : the size was that of a six-pounder, and it was quite hot. At the moment this phenomenon happened, the storm was near the zenith ; thunder was heard both be- fore and after, and rain fell with great violence: 47 it seems impossible, indeed, to conceive otherwise than that the aerolite must have been the offspring of the storm. We are of opinion that lightning often collects in its progress extraneous matter from the surfaces it pervades, and think that we have had in the examination of some effects of lightning the clearest evidence that such is the fact: lightning, in the spring of 1822, struck a horse chestnut, at Sarsden, Yorkshire; a ferrugino- resinous substance oozed out from the bark about five feet from the surface of the ground, and on analyzing a specimen submitted for analysis we detected the presence of nickel. M. Fusinieri has made some ex- ceedingly interesting experiments, which seem clearly to prove the transference of ponderable matter in the electric discharge; and the peculiar odour of electricity and lightning is only explicable on a supposition that it is attributable to the presence of extraneous matter, while the colour of the electric light and that of light- ning may also be dependent on foreign combinations ; thus it is red from iron or steel (it was red in the lightning that accompanied the fall of meteoric stones near Radicofani), green from silver, and so on. Thus nitrate of copper and boracic acid communicate to the flame of alcohol a green colour, nitrate of strontia, red, muriate of soda, &c. yellow. Green meteoric light is sometimes observed, and boracic acid is a volcanic product. In order to understand clearly Monsieur Fusinieri's interesting experiments, let us suppose the Leyden jar surmounted by a ball of gold, and the ball of the discharging rod to be of silver ; on the discharge having taken place, a trace of gold will be found on the silver ball, and a trace of silver on the ball of gold. This reminds us of an electrical experi- ment we made many years ago, and which appeared 48 in the Philosophical Magazine, of a somewhat ana- logous kind; the ball of the rod entering into the Leyden jar was coated with China ink, as was that of the discharging rod ; a vertical card was placed be- tween, and the electrical discharge effected : the card was, as usual, perforated, and a bur raised on each side; but besides all this there was a circular portion of the China ink displaced from each ball, and in the centre of both an indent discovered: we introduced this ex- periment among others to prove a double current ; but which the late Mr. Singer, if we remember right, contended was an evidence of what he called expan- sion : Fusinieri's experiments, however, clearly prove that our opinion was correct, and M. Moll of Utrecht, subsequently modified this, and at his request we transmitted a detail of these experiments to him. We subsequently made the following experiment in refer- ence to that of Fusinieri : Several folds of gold leaf were placed between the central leaves of a half quire of paper ; and it was found, when a powerful electrical discharge was passed through them, that the entire passage from the centre outwards to each external surface was stained with the purple oxide of gold. Let us finally consult the phenomena that announce the formation and fall of the meteoric stone : a peal of rolling thunder arrests "the attention, and the vision being directed to the ominous spot, perceives a bril- liant globe emerge from the dark cloud that conceals the elements of explosive fire, and on the wings of flame direct its flight to the earth. When the meteor has at length arrived, and the aerial stranger is inter- rogated, by " the torture of the fire and inquisition of the forge," as to its birth and origin, there is nothing elicited, we think, that can shake the conclusion, that the elements are terrestrial, and the proportionals the 49 mere exotic growth of the electric movements that pervade the exalted regions of the sky. Volcanic eruptions are always accompanied by a highly electrified state of the atmosphere. We are in- formed by Mr. Ronalds*, that he found in his experi- ments on Mount Vesuvius, in June and July, 1819, the atmospheric air constantly positive; the intensity increased as the sun rose, except when influenced by explosions of the volcano ; and the variations of intensity occurred very frequently. The difference between the highest and lowest degree of intensity amounted to nearly one third of the mean intensity. These variations occasionally accompanied changes of wind, which frequently succeeded six or seven times in the course of half an hour. Signer Gemmcllaro relates the following curious electric phenomenon, which occurred on Mount ^Etna, on the 2d of June, 1814: " Carbonaro, one of the guides, and the most advanced of the party, felt his hair stand on end, his forehead and face benumbed, and he heard a hissing noise : he took off his cap, and his hair became more bristled, and the whistling noise more powerful. The traveller nearest to Carbonaro also heard a humming sound, and asked the guide what it was. In the mean time they ap- proached each other, and were pleased with the magic sound. The traveller turned to call his companion, who was at some distance, and made a sign to him with his hand: the hand, when raised, produced a much stronger sound, so much so, that moving the fingers singularly modulated it. Finally, the three persons having joined, they experienced great pleasure, as, by moving their fingers, they produced the above extraordinary effect." During the convulsions of the * Professor Brande's Quarterly Journal, vol. xiv. p. 332. D 50 volcanic eruption, lightnings are seen to dart their forked fires across the mantle of clouds which issue from the crater, so well described by Sig. Monticelli of Naples, in the eruption of October, 1822, when Vesuvius exhibited the magnificent spectacle of a blazing cataract of liquid fire from the flowing of the lava, while dense and dark pillars of cloud, mingled with flame, ascended to the heavens, and the lightning amidst the sable canopy displayed its mighty corus- cations and scintillations, resembling " 1' enorme e rigoglioso pino ;" of which we have the following par- ticulars by Sigs. Monticelli and Covelli: On the 22d of October, 1 822, an enormous column of fire, two thousand feet high, rose from the top of the mountain, and lightning ascended from the crater, in the form of a pine, followed by numerous zig-zag flashes, which continued unceasingly to penetrate the rising cloud of cinders. Toward the middle of the night, the paroxysm of the volcano seemed to have been at its acme : the play of electricity, which embellished the elevated regions of the clouds of sand, became stronger, and acquired fresh vigour : at this moment the heavens presented a very unexpected scene ; zig-zag flashes of lightning passed in such quantities, either from the border of the clouds of sand into the air, or from one cloud to another, so that the edges appeared fringed with light, similar to an electric disc, throwing off con- tinued flashes of light. On the 2Sd, the continual discharge of the lightning, accompanied by awful thunder, fell on the most elevated points of the churches, houses, and trees : numberless flashes were observed to serpentize on all sides, coming not less frequently from the earth than from the heavens. The volcanic sand, which fell on the 23d and following days, was positively electrical. Prior to this memor- 51 able eruption, we descended into the crater several hundred feet, but are informed by a friend that, from its present condition, this is now impracticable. We consider the earthquake connected with volcanic agency. The air will be found highly electrical, and immense are the distances to which its influence ex- tends. During the earthquake at Lisbon, 1755, the celebrated St. Winifred's Well, at Holywell, suddenly ceased to flow, and continued so for three days. The late Dr. Muter, a clergyman of the church of Scot- land, informed us, that, on the morning of the day of the earthquake, he and a friend were walking together on the verge of Loch Lomond; the lake was then remarkably tranquil, unruffled by the slightest agitation; the waters, however, suddenly rose eight feet above their former level, and had well nigh swept them away. The great earthquake which occurred on the 13th of August, and was renewed on the 5th of September, 1822, that destroyed Aleppo, and buried more than 20,000 of its inhabitants, extended to many other towns in Syria. The shock was felt at Damascus, and in the Isle of Cyprus. In this case the vertical un- dulations were an extraordinary feature, these being generally, if not almost exclusively, in a lateral direction. It preceded little more than a month the eruption of Vesuvius already referred to. Before the first shock of the earthquake in Calabria, in the year 1783, many of the inferior creation evinced symptoms of terror and alarm. The fishes, in a state of stupor, came to the surface ; birds screamed, as they dashed through the air alarmed ; horses, oxen, &c. roared, and shook in every limb ; their eyes rolled and glared with terror ; in cats, their backs rose, and fur bristled up. The first shock was immediately pre- ceded by a sultry shower : the wind howled, and the D 2 52 sea rolled fearfully, and a subterranean noise was heard, like the rolling of violent thunder ; and then the earth rocked, and immense districts were con- vulsed to their foundations ; lakes and rivers suddenly appeared amid rocks and dry places ; towns and villages were overthrown, and the falling ruins crushed their tenants. Throughout Calabria 40,000 persons were destroyed, and 20,000 more fell victims to the epidemics which followed. Calabria, as well as the Caraccas, has often been the scene of these tragic events. In 1812, from information communicated to us by a native of Calabria, earthquakes had almost a diurnal return, and immense rents were formed by the earth opening beneath. Father Kircher witnessed the fate of Euphemia. The eye being directed thither saw nothing but clouds and darkness ; the vapours at length rolled away, and presented the frightful picture of a dark, dismal and pestilential lake where the city of Euphemia once stood. Extensive, indeed, are the ramifications of these convulsive throes. During an eruption of Hecla, upwards of twenty years ago, we are informed the atmosphere in that direction seemed to be affected: it appeared to consist of denser materials, and of an orange-red colour. Mr. White, in his " Natural History of Selborne," says, " the summer of the year 1783 was an amazing and por- tentous one ; for, besides the alarming meteors and tremendous thunder storms that affrighted and dis- tressed the different counties of this kingdom, the peculiar haze or smoky fog that prevailed for many weeks in this island, and in every part of Europe, and even beyond its limits, was a most extraordinary appearance, unlike any thing known within the memory of man. The sun at noon looked as blank as a clouded moon, and shed a rust-coloured ferruginous 53 light on the ground and floors of rooms, but was par- ticularly lurid and blood coloured at rising and set- ting." Now during these phenomena witnessed in Britain, Calabria was convulsed to its centre, and Sicily torn by earthquakes, while on the coast of Norway a volcano emerged from the sea, like that witnessed by the crew of the Sabrina off the Azores, but which we believe has since sunk. D 3 CHAP. VI. PHENOMENA OF VEGETATION. DUTROCHET's THE- ORY. ANIMAL ELECTRICITY. ASCENT OF THE SPIDER. IT seems highly probable that the entire chain of the phenomena of vegetation is influenced by electri- city, or electric currents. Electric gleams were first observed by the daughter of Linnaeus to play in the evening on the flowers of the Indian cress ; and the attachment of dew to the points of leaves appears connected with the same principle.* The recent beautiful theory of Dutrochet seems to confirm these observations. According to our author, the roots absorb water, with such soluble matter as may be present ; this flows upwards to the leaves, through the lymphatic tubes of Decandolle, and which are found both in the soft and hard wood ; this fluid solution as it ascends absorbs laterally a portion of the already elaborated and assimilated sap, to form the leaves. Being carried up to the leaves in spring, the sap there undergoes a chemical change, evolving oxygen by day, and carbonic acid gas at night: thus assimilated, it again returns, descending through the bark and soft wood, and giving off laterally in its descent elaborated sap, finally changed into bark and wood. Thus the radiated tracheae of the wood give off and disperse laterally the ascending juice of the lymphatic tubes, and those of the bark the descending or nutritive and * Mr. Forster has also observed a lambent electric light about the leaves of plants. 55 elaborated juice to the bark ; the first adds a new layer of alburnum, or young wood, and the second a new layer of liber, or inner bark. M. Dutrochet found an interesting illustration of this in some of his experi- ments. He took the ccecum, or blind gut of a chicken, and, having nearly filled it with milk, it was immersed in water, which was found to be absorbed laterally; after some time the milk underwent chemical decom- position, and the water that had been absorbed was expelled by the same orifices through which it had previously entered. Suppose a glass tube had been inserted into the caecum ; it is evident that when the water was absorbed the liquid must have risen in the tube, as exemplified by Dr. Hales in his experiments on the bleeding vine, and still more interestingly so in one made by Mr. Braddick, who, having attached a bladder to the orifice of a bleeding vine, found that in twenty-four hours it expanded, and became as hard as a cricket ball, and in some hours after burst with ex- plosive force. A curious fact was lately communicated to us, and which we consider in some measure corro- borating Dutrochet's theory. A twig was picked up in a wood during a severe frost, with part of its bark detached : from this denuded surface an innumerable quantity of minute capillary filaments of ice protruded ; they were parallel to each other, and horizontal. It appeared, that the sudden expansion of the fluids included in the tubes already described had projected jets in a horizontal direction, through the lateral orifices, and which, being suddenly congealed, pre- sented the curious phenomena already described. As a verification of Dutrochet's opinion, it should be remembered that electricity is always efficient in every chemical change ; therefore, when the milk passes into the acetous fermentation, its power is exemplffied, and D 4 56 must act very dissimilarly during that phenomenon to what it does before decomposition ensues. The ascent of liquids in virtue of capillary attraction is a problem the solution of which has perplexed the enquirer, and, in truth, we know not how it is to be explained apart from electrical attraction. The substitution of recent blood for milk in Dutrochet's experiment beautifully illustrates his position ; because the finally expelled liquid will be tinged red by the coloured globules of the blood, and thus dye the liquid medium which surrounds the cellular tissue. There are peculiar phenomena in vegetable phy- siology wherein an unusual quantity of limpid water is secreted by the plant, and which in all probability is connected with some organisation peculiarly acted on by electricity. Thus, what has been called the wild pine, an exotic found in South America and the West Indies, and parasitic on the trunk and branches of some trees, is composed of foliaceous bags, serving as reservoirs for water obtained from the atmosphere, in the form of dew or rain. These severally contain from a pint to a quart of water, and an appendage prevents its evaporation ; it becomes an interesting resource against thirst, both to the inferior animals and man, and no doubt the former class are well acquainted with these providential supplies ; at least it has been ascertained that animals of the Simia, or monkey kind, are no strangers to the fountains of supply contained in the pitchers of the Nepenthes distillatoria. In the case, however, of the wild pine, as well as the Sarra- cenia adunca, &c. in which last are also pouches for the reception and retention of water, they may be considered as vegetable tanks or cisterns : it is different in the Tillandsia, or " water with " of Jamaica ; since here, as well as in the Cissus latifolia of the East 57 Indies, it is evidently a secretion of the plant : a piece of the former, two or three yards long, supplies a copious draught of water ; and when the latter is cut, it is found so full of sap that a continued stream flows out. The watery fluid found in those Curious fol- liaceous adjuncts, the pitchers of the Nepenthes distil- latoria, is evidently a vegetable secretion ; because we have seen it contained in the pitcher before the lid had opened, and shall elsewhere give our chemical examination of this liquid, as well as a description of the curious mechanism of the lid.* There is a phenomenon in vegetable physiology to which we have paid considerable attention, and last sum- mer observed an extraordinary instance of the kind : it is described, because it seems to be associated with electricity. Doubtless many streams, rivulets, and rivers, owe their source and vigour to a similar cause, and have had their occult springs amid the deep recesses of the forest : the condensation of vapour, as in fogs by trees, that otherwise would exhale in the sunbeam, or dissolve in the aerial abyss, is a curi- ous and interesting phenomenon. We find that by act of parliament it is expressly provided that no tree shall be suffered to remain, or be planted within fifteen feet of the public roads, and that commissioners of .roads are authorised to cut down every such tree ; this however is, we are afraid, seldom attended to. In Kentucky many brooks are pointed out which now fail * The Nepenthes distillatoria is a native of Ceylon, Amboyna, Madagascar, and other places, as well in Asia as in South Ame- rica. Its leaves and stalks are very vascular; and the inflated pitchers contain two or more ounces of liquid. The Cola. (Ethiopica, and Agapanthus umbellatus, sometimes, after having been freely watered, distil from the tips of their leaves liquid matter. D 5 58 in summer, a circumstance unknown twenty or thirty years ago ; and in New Jersey, where the woods have been cut down, some streams are altogether dried up. The author of" The Journal of a Naturalist" remarks, in reference to the condensation of vapour by trees, " That a young wych elm in full leaf affords a good example ;". and mentions a well marked case of this kind : " The weather had previously been very fine and dry, and the road in a dusty state ; but a fog coming on, an ash tree hanging over the road was dripping with water so copiously that the road beneath was in a puddle, when the other parts continued dry." * Mr. White, who seems to have allowed almost nothing to have escaped his intelligent watchfulness, says " In heavy fogs, on elevated situations especially, trees are perfect alembics. In Newton Lane, in October, 1775, on a misty day, a particular oak in leaf dropped so fast that the cart-way stood in puddles, and the rims ran with water, though the ground in general was dusty." Evergreens might thus be planted with advantage round ponds where a perennial supply is wanted ; and if we mistake not, we have seen demon- strable evidence of this description in the case of a circular pond, at Castle Kennedy, the seat of the Earl of Stair, whose venerable woods and sylvan beauties, we regret to learn, are doomed to be destroyed. Rain will always be more frequent and copious, and oftener repeat its periodic return, to the spot shaded by trees, than in open districts of the country, and apart from them ; a fact of the utmost importance in Reformation of roads, and should never be lost sight of. The intel- ligent traveller, in looking around him, must feel per- suaded of this palpable truth : many a rill, and even * Journal of a Naturalist, Lond. 1829. p. 62. 59 river, has disappeared where woods have been levelled. The great features of a country have been thus changed ; and we doubt not but rivers have rolled in ancient Caledonia before her forests were felled, and of the existence of which we have now no memorial, except in the organic remains occasionally exhumed from the deposit of the channel of a former river ; thus our intelligent friend, Patrick Neill, Esq. has clearly proved that the beaver was once indigenous to Scot- land * : it is, however, America that presents less equivocally the picture consequent on dried-up rivers. The geologist should not omit this important truth in his speculations, for it will certainly solve satisfactorily some phenomena in alluvial deposits. It must have been observed, that, under circum- stances when the roads have been parched and dusty, the surface of the ground round particular trees has been so saturated with moisture as if it had rained copiously on these favoured spots, and nowhere else ; and according to our numerous observations, the elm seems remarkably prominent here. Glas, in his account of the Canaries, informs us, that in one of these islands the entire supply of water proceeds from a vegetable source, and that it is measured out to the inhabitants under the jurisdiction of the municipal authorities; dense clouds proceeding from the ocean, are attracted by a tree, which grows on the declivity of a hill, and the vapour here condensed falls in the form of -a shower into a tank beneath; it is therefore called the " raining tree." In the month of July last we witnessed a striking instance of this kind in the * In the time of Giraldus Cambrensis, the only beavers re- maining in Wales or England were in the river Towy : " Inter universes Cambriae, seu etiam Loegriae fluvios, solus hic(Teivi) castores habet." This was about the year 1170. D 6 60 vicinity of Stafford, on the Lichfield road : clouds of dust rose on the main road, and a dense fog hovered over it ; but no moisture was precipitated except in the vicinity of the trees and hedges ; and here the deposi- tion was considerable, but especially in the case of a lofty insulated Lombardy poplar, where the fall was so considerable that it might have been used as an ad- mirable shower bath, and so complete a rivulet was formed as might have been directed with effect to turn the wheel of a saw-mill. Thus rivulets may be created by plantations, and have been formed by them : the pond embosomed in woods will rarely dry up, and its supplies be seldom exhausted ; while gentlemen may hereby obtain a useful hint in reference to ornamental landscape. By a considerable increase of our woods the climate may eventually be entirely changed ; and, on the other hand, by the introduction of trees arid wastes may be softened down into a genial soil, sus- ceptible of cultivation : even parched islands, such as Antigua, &c., might be reclaimed from that drought to which their inhabitants are frequently doomed. It is in the oases of the desert that wells are found : " They came to Elim, where were twelve wells of water, and threescore and ten palm trees ; and they encamped there by the waters." * These remarks may be considered somewhat exotic, though all are, indirectly at least, allied to the subject, and it is presumed that their interest may be found sufficiently apologetic. We have been informed that a gentleman, who has paid great attention to experiments on electricity, dis- covered, one evening, on his return home, the spiny summits of a thorn singularly studded with stars of * Exodus, xv. 27. 61 electric light : and it may be added, that Dutrochet is of opinion negative electricity imparts the powers of absorption, and positive electricity those of secretion. M. Astier concludes that the leaves, thorns, and hairs of plants tend to maintain in them the requisite propor- tion of electricity ; and by drawing off from the atmo- sphere what is superabundant, act in some measure as lightning rods, or paragreles. Astier insulated the thorns of growing plants ; and upon being exposed to the atmosphere when the electrical equilibrium was disturbed, they distinctly affected the electro- meter. The electric powers of certain kinds of fish have been long known, such as the torpedo, silurius elec- tricus, gymnotus electricus, trichiurus indicus, and tetraodon electricus. While the torpedo, a fiat fish of the ray kind, was well known to the ancients, it does not appear that the peculiar properties of the gymnotus electricus were recognised before the end of the seven- teenth century ; and it was Mr. Walsh that first identified this singular phenomenon with electricity. Humboldt give us, in his " Personal Narrative," an amusing account of the method practised in South America for catching the electrical eels, by means of wild horses forced into the water, the electrical eels becoming finally exhausted by an expenditure of their energy : by these animals, as in common electricity, the shock is freely communicated through conductors, but not transmitted through electrics ; and when the shocks of the larger gymnoti are passed through an interrupted circuit, they even yield the electric spark : the electric organ consists of an extensive series of irregular columns divided by horizontal partitions which expose a considerable surface ; and the interstices seem to contain a fluid, which may give rise to the 62 electric influence. The torpedo is found in the Medi- terranean and North Seas, rarely exceeding eighteen to twenty pounds weight ; and the rapidity with which it communicates the shock is considerable, sometimes amounting to fifty in a minute and a half: it should seem that the shock is dependent on the will of the animal, and each shock accompanied by a depression of the eyes, while the intensity is stated to be four times stronger when the fish is insulated and surrounded by air. We were informed by Signor Mojon, professor of chemistry in the University of Genoa, when there, that it was endeavoured to ascertain by experiment, whether a series of torpedos, arranged in separate tubs, and conjoined with con- ductors, in the manner of the Couronne des Tasses, would decompose water, as in common electricity : the attempt, however, was unsuccessful ; nor do we think that this might have been expected, because it would have required a series of simultaneous shocks, as well as a continuous succession of them to have produced the effect. * Heat seems to increase the electric pro- perty in these animals ; and we were told that the tem- perature of the water in which one of these fish was placed having been accidentally raised too high, Mr. Walsh, by incautiously handling it at the moment, received so violent a shock as to lay him prostrate. On the authority of Spallanzani, the dying torpedo com- municates its shocks more frequently than at other times, but they are then feebler ; and the same natu- ralist assures us that the youngest torpedo can exercise the property in question. The gymnotus electricus, * A posthumous paper of that much lamented and distinguished philosopher, in reference to this subject, has been lately read before the Royal Society. 63 or Surinam eel, abounds in the rivers of Surinam * and Senegal: it is generally about three feet long, but occasionally met with ten to twenty feet long, sufficient even to kill a human being: the nerves immediately con- nected with these organs are larger than in other parts of the system : these have a reference to temperature, and a comparative relation to the media of air and water, the latter being an inferior conductor, and the former, when quite dry, being an electric of a superior kind, and only changing its character by means of the watery vapour it contains. We are of opinion that the electric organ of the torpedo perhaps we may extend it to other electrical animals is more subser- vient to the process of digestion than to that of catch- ing its prey ; and this opinion is also maintained in a late volume of the Transactions of the Linnaean So- ciety. The curious experiments of Dr. Wilson Phillip go to prove that the galvanic influence produces an analogous result to that of the nervous power, and seems, in his researches, to have been successfully substituted for it. From the preceding observations it is evident that the animal machine is intimately con- nected with electricity, and we may infer this applies not merely to those extraordinary fish now reviewed, but to all animals, though in the torpedo, &c. it be most conspicuous, and the energy more concentrated ; it is sufficiently obvious, therefore, that atmospherical electricity must affect the animal system more or less, and modify its powers of action ; and the same thing applies to the process of vegetation : it is well known that when we rub the back of a cat, electric sparks are * A physician informed us he has frequently received a shock from the gymnotiis electricus, in the rivers of Surinam, by touching the fish with a dirk : it extends considerably up the arm, inducing a benumbing torpor or paralysis. 64 copiously emitted, but it is not so generally known that if we do this and lay one hand on the throat of the animal, while we apply the other to the back, we shall receive a distinct electric shock : an experiment first pointed out by Glover. Mr. White describes a case of intense frost, and adds, " During those two Siberian days, my parlour cat was so electric, that had a person stroked her, and been properly insulated, the shock might have been given to a whole circle of people." The insect world seems to be as powerfully affected by aerial electricity as any other. Huber, it would appear, has from repeated observation proved that electricity is immediately concerned in the secretion of honey ; that bees are especially active and labo- rious before the approaching storm, when the air is warm and humid and the wind is from the south. " Insects seem particularly excited by a high electric state of the atmosphere, and are then found more numerous on the wing than at ordinary periods and toward evening ; and sometime before the storm comes on, various kinds may be then seen that do not appear at ordinary times, but immediately before the storm all disappear." * These facts and a variety of kindred phenomena must have been often observed even by individuals the most inattentive to the won- ders that surround them. D'Isjonval believed spiders were peculiarly susceptible of aerial electricity, and that the extent of the threads they spun were pro- phetic of the kind of weather that was to follow : if these were long, fine weather would succeed; and, on the contrary, if they were short, stormy weather and rain followed. An anonymous writer, under the signa- ture of " Carolan," considered that the spider's thread * Kirby and Spence's Introduction, &c. Lond. 1828. 4 vols. 5th edition, p. 204. 65 when propelled by the insect was invested with some subtile aura which might be of an electric kind. The power possessed by some kinds of spiders of propelling their threads into the atmosphere, and of effecting an aerial ascent, are among the most recon- dite and curious problems in natural history, facts, though long questioned, substantiated beyond a doubt. In a paper published in the Memoirs of the Wernerian Society of Edinburgh, we endeavoured to prove that it was an electrical phenomenon^ and the facts to which we referred seemed, to us at least, to be conclusive. M. Gay Lussac having found that though a soap bubble ascends readily sub die, it does not ascend within doors, ingeniously, as an inductive consequence, ascribes the rise of the clouds in the air to the impulsion of the ascending currents resulting from the difference of temperature between the surface of the earth and the superior regions of the atmosphere : this is precisely the principle which Mr. Blackwall of Crumpsall Hall has applied more recently to the ascent of the gossamer spider. Many phenomena seem to militate against this view of it: in the first place these ascending currents have a problematical existence : it is not denied that caloric radiates from the earth to the heavens, but this is chiefly nocturnal ; and it is presumed cannot be that referred to, because our aeronauts then descend ; and if we are not strangely mistaken, these apterous insects ascend most readily when the solar rays are most powerfully impinging on the terrestrial surface. Mr. Blackwall has described a most extrordinary circumstance, namely, the ascent of a tissue of spiders' threads and cobwebs of various lengths and breadths. As far as we know, nothing of the kind has ever been observed by the most acute and diligent naturalists ; and therefore the phenomenon, 66 as to any parallel record, is altogether unique ; and did it not appear uncourteous, we should rank it either sui generis or a deceptio visus. Showers of cobwebs, and the descent of spider's threads, we, in common with many others, have frequently witnessed. Mr. Black- wall has, however, from this assumed fact, concluded that the myriads of gossamer spiders which have de- scended at night are raised bodily upwards, webs and all, into the air by the impulse of these heated eman- ations, and when they cease alight on the earth. It may here be legitimately asked, how it happens that the aerial spider ascends after that period of the day when these ascending currents are supposed to cease, and that the spider will descend when they are presumed to be in active operation ? And further it may also be reasonably enquired, how is it that the spider descends in the face of such a buoyant efflux, arid as immediately, having projected its thread, ascends again ? These are difficulties to which, on this hypothesis, it will be found no easy matter to return a satisfactory answer. More- over, in the heat of the day, our hedges are occasion- ally full of floating threads, often stretched across' the road, or extending from tree to tree, or waving in the wind ; and when these heated currents should be at work, our meadows will be one tissue of gossamer obstinately attached to the ground ! So much then for the question of ascent. It has been also contended that spiders possess no power to propel their threads unless aided by a current of air. This last, resolving itself into a totally different phenomenon, must be considered apart from the others. In order to put this to the test of experiment, Mr. Blackwall insulated some spiders on a twig by sur- rounding it with water, and covered them with a bell- glass ; and since it appears that the imprisoned insects 67 never attempted to make their escape, it is concluded that they were utterly unable to propel a thread to the extent of even the fraction of an inch. To this and to every thing else that Mr. Blackwall has advanced on the subject, Mr. Rennie in " Insect Architecture," says " Amen." Now, without assigning to these spi- ders the intelligence and sagacity of Mahomet's spider, it seems very natural to suppose they were sensible that their range was bounded by the crystal hemi- sphere which covered them. Be this as it may, we had, in the communication alluded to, mentioned the fact of the propulsion of a thread in the very " teeth " of an aerial current ; but the spider can also dart a thread instanter the next moment to the ceiling, and at right angles with the other : and not limited to a longitude of inches, the gossamer spider occa- sionally propels, with the rapidity of a ray of light, a thread from 20 to 30 feet long ! That a current of air may enhance this power of propulsion in the insect is very likely to be the case, and that it has also the property of darting this counter to the current is an undisputed fact. It remains only to be determined whether this can be effected in tranquil air mader any circumstance. In the bright sunbeam we feel per- suaded the gossamer spider can propel its threads, be the air ever so calm and motionless. The philosopher of Selborne, to whose authority we are always happy to make an appeal, observes, in reference to the gossa- mer spider, " Last summer one alighted on my book as I was reading in the parlour ; and running to the top of the page and shooting out a web, took its de- parture from thence. But what I most wondered at was that it went off with considerable velocity in a place where no air was stirring, and I am sure I did not assist it with my breath." Mr. Blackwall consi- 68 . ders, moreover, that the threads " are drawn out by the ascending current of rarefied air," though it is difficult to conceive what connection this can have with " air blown upon them," and when the ascent is stated to have taken place on the 1st of October, 1826, there was " no wind stirring." " By blowing gently toward its position," (the spider ?) Mr. Rennie " had also the pleasure of seeing the double or bend of the thread that was blown into the air;" and he has also ob- served that the spider " can produce a line, not only when the current of air is strong," but also " when there was scarcely a breath of air." In reference to currents of air it may be here stated, that Mr. Black ascertained in the Mediterranean by many experiments, that winds or currents of vapour of some continuance from the sea are invested with negative electricity, and those from the land positively electrical ; and in the case of opposing currents in different electrical states, a transference of electri- city follows. In the autumn of 1818, Signer Mor- richini of Rome informed us, during our visit there, that he had found the solar spectrum invested with electric properties. Savario Barlocci, and Carlo Mattrucci of Forli, have since also proved the com- munication of electricity by the solar ray. The latter observed that the glass plate which became electric by the sunbeam never evinced this property when the disc of the sun was obscured by a cloud. Excited by the action of the solar ray, or a current of air, which by the experiments of Bennet, and other elec- tricians, is sufficiently proved to be an excitant of, or to induce, electricity, the gossamer spider propels its threads into the air ; and when sufficiently buoyant, ascends in its silken balloon and parachute con- structed of them : the threads, imbued with electricity 69 by their impulse through the air, are preserved electric by the continued action of the electricity of the solar ray. We have found that an electrified soap-bubble ascends within doors, and Mr. Bowman, F. L. S., has described a phenomenon which is perfectly inexplica- ble, except on the supposition that the threads are in- vested with electricity : it is the ascent of the spider by two distinct divellent fasciculi of thread sseparated by a considerable angle. On the 28th of July, 1829, we made numerous experiments with the aeronautic spider, in a hay-field near Hull ; and found in one case that three of these insects, being suffered to ascend from the same spot, moved each in a contrary direc- tion. In No. XII. of the Magazine of Natural His- tory, p. 147., Mr. Thompson describes a singular flight of spiders observed by him in St. John's church, Hull, on the 19th of that month: " The tops of ladies' bon- nets were generally the places whence they commenced their flight, and in it they seemed not to be confined to any particular direction : some flew upwards at a slight angle, some north, some south, some east, some west ; and in so doing several passed so near to each other that I cannot conceive, as they passed m oppo- site directions, that any current of air conveyed them, as two opposite currents could scarce exist so often close to each other." It would, however, be injudicious to pursue these curious investigations in this place ; since the subject is discussed more amply elsewhere *; and it is presumed that the proofs drawn from the multitude of experiments and observations there re- ferred to, amount nearly to demonstration. The descent of the gossamer, which there is every reason to suppose is produced by the insect in the atmo- * " Researches in Natural History," Second Edition. 70 sphere, and not carried up from the surface of the ground, seeing it is not denied that the spider can, when suspended in the air, shoot out its threads, will always be the precursor of rain or storms : every additional thread propelled, in all probability, carries the spider to a higher elevation. 71 CHAP. VII. UNEQUAL DISTRIBUTION OF TEMPERATURE. THE METEOROLOGICAL FEATURES OF THE CLOUDS DE- PENDENT ON THEIR ELECTRIC CHARACTER. DEW. RAIN. HAIL. DESSAIGNES has shown that heat modifies the kind and quantity of electricity ; that, in fact, electricity is excited whenever any body is unequally heated : and it may therefore be considered an unequal distribu- tion of heat and moisture in the atmosphere will deter- mine the evolution of the thunder storm. We were much surprised at the very rapid change of temperature which took place during a thunder storm near the Rhine, observed in 1825; the extreme limits of this vibration of temperature amounted to nearly 14 F. and the oscillations were exceedingly abrupt: the curious configurations of the clouds, and all their numerous ramifications and modifications owe their being and change to electric power and influence. Mr. Howse, a very extensive traveller in the regions of North America and among the Esquimaux tribes, mentioned to us a very extraordinary phenomenon witnessed by him, in the atmosphere about latitude 57- : the entire atmosphere seemed like eddies and circles in constant motion, widening and falling into each other, and beautifully coloured green and red, &c. : this continued for many hours, and was observed by another individual at the same time, though nearly 150 miles distant. Clouds are understood to be visible aggregations of minute aqueous particles held in sus- 72 pension in the atmosphere ; and such may cease to be visible from their extreme attenuation or diffusion, or melt away in the atmosphere, being dissolved ; or their destruction may be effected by resolution into rain. We are indebted to Mr. Howard for an arrange- ment and classification of the clouds : they are com- prehended under the general terms, cirrus, cumulus, and stratus ; these occasionally combine or mix toge- ther, and produce intermediates, as cirro-cumulus and cirro-stratus ; there is also the cumulo-stratus, and a combination of the entire three, the cirro-cumulo- stratus, nimbus, or rain cloud. Generally speaking, the three simple forms of cloud are suspended at different degrees of elevation in the order in which they are placed, the cirrus being highest, and the stra- tus lowest ; the latter appears generally reposing on the verge of the horizon : the cirrus has been called the Proteus of the skies, from its frequent and rapid changes ; it is the first cloud seen in clear weather : sometimes pencilled and thready, or fibrous, oft- times the end resembles a brush ; this form of the cloud may be considered as at antipodes with the nim- bus, or storm cloud, and dry weather, easterly winds, and luminous meteors, or shooting stars, are its usual attendants : the cumulus is exhibited, as it were, in flocculi or fleeces, or patches, acting occasionally as skreens to intercept the sunbeams : before rain they increase rapidly, and descend to a lower plane in the atmosphere : in some cases they present hemispherical masses, like alpine ranges with fleecy summits; are occasionally seen to evaporate as soon as formed, or an aggregation is formed by numbers of these coales- cing : these modifications and inosculations are doubt- less the effects of an electric change : when the cirrus and cumulus together form the cirro cumulus, they 73 present what Bloomfield has very elegantly compared to " The beauteous semblance of a flock at rest." The stratus, agreeably to what has been stated, is the lowest of the clouds ; it rests on the plane of the horizon, or settles on the earth or water ; it has* been called the cloud of night, ascending into the atmosphere in the morning, and sinking at night. The dense fogs of autumn and winter are referable to the stratus or its modification ; hence also mist, which is the same thing, and which so often shrouds the mountain traveller : the fine mists which creep or steal along the valleys in a summer's evening are generally white, and have a beau- tiful and interesting appearance when silvered by. the moonbeams : when the sky is mottled with cirro-stratus it occasionally gives rise to what has been called the " mackarel-backed sky : " in the evening and morning it is often painted with beautiful colours, the occa- sional canvas of the most brilliant and vivid tints ; different shades of purple, crimson, lake, and scarlet, these are the most prevalent colours : the horizontal sun, accompanied by haze, indeed, refracts different colours at different times ; but yellow, orange, a golden hue, red and lake, are those most commonly observed. The cumulo-stratus varies in appearance ; sometimes it seems like a cauliflower or a vast mushroom, and at other times resembles a range of mountains silvered with snow. When the cumulo-stratus is formed, it occasionally becomes dense and deep, and enveloped in a portentous darkness, ominous of the approach of rain. Such a phenomenon was descried by the pro- phet's servant from the summit of Carmel: it was at first, indeed, no " bigger than a man's hand," but it swelled in magnitude " till the heavens were black with 74 clouds and wind, and there was a great rain ; " and this phenomenon has actually been witnessed by Dr. Walsh from the same interesting spot. Before thunder storms the cumulo-stratus becomes reddish, or copper colour. The nimbus or storm cloud is thus described by Mr. Forster : "In stormy weather, cumuli may be seen rising into mountains, and becom- ing cumulo-strati, while long strata of cirro-stratus per- meate their summits, and the whole phenomenon has the appearance of a range of mountains transfixed by the mighty shafts of giants : after having existed some while in this form, they become large and irregular, and they get darker by intensity, till they seem con- centrated in a dense black mass, with a cirrose crown extending from the top, and ragged cumuli entering from below; and eventually the whole resolves itself into rain." * The stratus form of cloud is found to be highly charged with positive electricity, and the anastomosis and coalescence of the several varieties of the cloud, with their condensation and final resolution into rain, are all so many modifications and states of intensity in their electricity, which, when concentrated in the storm cloud, at length pours down its destructive elements : the stratus has been seen hovering over the surface of lakes, as at Windermere, &c. and being attracted by the mountains, has discharged its elec- tricity against their sides, like an electrical battery. Mr. Glover, the celebrated landscape painter, informed us that he has seen this. Clouds are sometimes sin- gularly disposed in radii, pointing to the sun's repose : witness the scenic picture of a setting sun, and all its painted assemblages of clouds that, like ministering servants, wait on the day's adieu. Clouds being there- * Researches about Atmospheric Phenomena, Svo. 1815. London, 2d edition, p. 26. 75 fore visible aggregations of vapour, are more or less dense, agreeable to the amount of attractive power that causes the parts of which they are composed to cohere or coalesce : those masses of vapour are reple- nished through the medium of evaporation, which is a process incessant in its operations, in the ordinary state of the atmosphere. The aeronaut and the mountain traveller often penetrate the clouds and rise far above them, and they are thus easily ascertained to be col- lections of vapour ; fogs and mists are of the same description, only exhibited in another form : these vapours, then, consist of aqueous particles, interspersed with air, which lessens their specific gravity. The unequal distribution of temperature in the atmosphere, dependent on a variety of causes, will give rise to those local patches of clouds, and their partial diffusion, which present so many varied, and not unoften fre- quently changing aspects : the loftier their elevation the more diffuse and less aggregated they become, and the lower the plane to which they descend, the denser they must necessarily be, till they coalesce into the nimbus, or form the storm-cloud with all its aerial artillery and elements of destruction. The rise and fall of the clouds has its expression in the oscillations of the barometer, since the more dense the atmosphere the greater will be the pressure on the surface of the mercury, and the more buoyant is its power in reference to the " balancings of the clouds." That electricity is intimately concerned in all this will be admitted by every one at all conversant with atmospherical electricity : not a change takes place among the clouds but the fact maybe found announced by the aerial electroscope, which, though on the surface of the ground, becomes a faithful telegraph of what is doing in the heavens. E 2 74 clouds and wind, and there was a great rain ; " and this phenomenon has actually been witnessed by Dr. Walsh from the same interesting spot. Before thunder storms the cumulo-stratus becomes reddish, or copper colour. The nimbus or storm cloud is thus described by Mr. Forster : "In stormy weather, cumuli may be seen rising into mountains, and becom- ing cumulo-strati, while long strata of cirro-stratus per- meate their summits, and the whole phenomenon has the appearance of a range of mountains transfixed by the mighty shafts of giants : after having existed some while in this form, they become large and irregular, and they get darker by intensity, till they seem con- centrated in a dense black mass, with a cirrose crown extending from the top, and ragged cumuli entering from below; and eventually the whole resolves itself into rain." * The stratus form of cloud is found to be highly charged with positive electricity, and the anastomosis and coalescence of the several varieties of the cloud, with their condensation and final resolution into rain, are all so many modifications and states of intensity in their electricity, which, when concentrated in the storm cloud, at length pours down its destructive elements : the stratus has been seen hovering over the surface of lakes, as at Windermere, &c. and being attracted by the mountains, has discharged its elec- tricity against their sides, like an electrical battery. Mr. Glover, the celebrated landscape painter, informed us that he has seen this. Clouds are sometimes sin- gularly disposed in radii, pointing to the sun's repose : witness the scenic picture of a setting sun, and all its painted assemblages of clouds that, like ministering servants, wait on the day's adieu. Clouds being there- * Researches about Atmospheric Phenomena, Svo. 1815. London, 2d edition, p. 26. 75 fore visible aggregations of vapour, are more or less dense, ngreeable to the amount of attractive power that causes the parts of which they are composed to cohere or coalesce : those masses of vapour are reple- nished through the medium of evaporation, which is a process incessant in its operations, in the ordinary state of the atmosphere. The aeronaut and the mountain traveller often penetrate the clouds and rise far above them, and they are thus easily ascertained to be col- lections of vapour ; fogs and mists are of the same description, only exhibited in another form : these vapours, then, consist of aqueous particles, interspersed with air, which lessens their specific gravity. The unequal distribution of temperature in the atmosphere, dependent on a variety of causes, will give rise to those local patches of clouds, and their partial diffusion, which present so many varied, and not unoften fre- quently changing aspects : the loftier their elevation the more diffuse and less aggregated they become, and the lower the plane to which they descend, the denser they must necessarily be, till they coalesce into the nimbus, or form the storm-cloud with all its aerial artillery and elements of destruction. The rise and fall of the clouds has its expression in the oscillations of the barometer, since the more dense the atmosphere the greater will be the pressure on the surface of the mercury, and the more buoyant is its power in reference to the " balancings of the clouds." That electricity is intimately concerned in all this will be admitted by every one at all conversant with atmospherical electricity : not a change takes place among the clouds but the fact maybe found announced by the aerial electroscope, which, though on the surface of the ground, becomes a faithful telegraph of what is doing in the heavens. E 2 76 M. Fresnel supposes that the particles of air inter- posed between the globules of vapour always maintain a superior temperature to that of the surrounding air ; the cloud, therefore, intercepts the heat of the solar rays, and its temperature is raised higher than the air that surrounds it ; such is the ingenious cause of the flotage of the cloud assigned by M. Fresnel. Gay Lussac, however, considers the ascent of clouds and their buoyancy entirely attributable to the ascending currents which take place from the earth ; and are the consequence of the difference of temperature between the air in the superior regions of the atmosphere and that in contact with the surface of the earth. Alpine districts are the most favourable situations for the study of the formation of clouds. Among the valleys at the foot of the range of the Apennines, we have wit- nessed the " cloud of night " starting from its repose, creeping up the mountain acclivity, towering above the summit of the mountain range, and finally melting away in its eagle flight. The aerial vapours, when careering through the sky, have been observed to avoid, as by instinctive repulsion, the aiguilles and shelving ridges of the mountain, and bounding over in a con- centric curve, glide into the valley beyond : this curi- ous phenomenon has been very properly ascribed to electricity. The mean altitude of the clouds has been estimated by Mr. Leslie at two miles at the polar, and four miles and a half in the equatorial regions. In Dr. Well's theory of dew we are supplied with an elegant solution of the problem of its formation and preceding cause : the whole phenomenon is dependent on radiation : a still atmosphere and a clear nocturnal sky are necessary conditions ; the heat radiating from bodies on the terrestrial surface reduces their tem- perature below that of the atmosphere in contact with 77 them ; the consequence is a precipitation of moisture on their surface, or in other words dew is formed, and those objects become bedewed in the ratio of their con- duction of heat ; hence bars of silver and copper would sooner be so than those of gold or platinum : it de- pends, therefore, precisely on the same principle which produces the deposition of dew on the exterior sur- face of a glass vessel remaining in a warm room, when water brought immediately from the pump well is poured into it. Rain is formed of condensed aqueous particles precipitated from the nimbus, and will be more or less violent, or more or less dense in respect to the drops that fall, according to the intensity of the electricity which invests the cloud : for the electricity, when concentrated to a vast amount, will finally burst its envelope, and in its descent will carry with it the the watery contents of the cloud, and in proportion to the accumulation of electricity, and the greater or less sudden rupture of the cloud, will be the violence of this precipitation : the rain which falls has been frequently found electrical, sometimes positively, and at other times negatively. Snow is congealed aqueous vapour, and occasionally exhibits elegant and varied configurations. In the Edinburgh Philosophical Jour- nal, we have an account of a shower of luminous snow, by the Rev. Colin Smith : towards the end of March, 1813, a party of gentlemen were returning homewards from Ben Cruachan, in Argyleshire, when in crossing the lake (Lochawe) in a boat they were over- taken by a singular snow storm : the lake, which was of glassy smoothness, with their boat, clothes, and all around, presented a luminous surface, forming one huge sheet of fire ; nor were the exposed parts of their bodies singular in this respect, for to the eye they all seemed to burn, although without any feeling E 3 80 the facts : "It took place on the Stipperstone Hill, about five o'clock p. M., in the month of May. The appearances preceding the phenomenon were a hazy atmosphere, a stillness in the air, and an oppressive heat in the lower regions, although the hills were im- mediately after covered over with hail ; and at Pontes- bury, a village about a mile distant from the spot, the hail lay a foot deep, and most of the stones measured two inches in circumference ; the storm was accompa- nied with vivid flashes of lightning and loud thunder. The great body of water divided before it reached the village of Minsterley ; but at Pontesbury it was twenty feet deep ; it caused the river and brooks to overflow, almost instantaneously, their banks, and extended for miles over the adjoining country: the damage occa- sioned by this calamitous event amounted in the aggre- gate to el 5,000, and fifteen individuals perished. About the time of the catastrophe it was evident that the air was highly charged with electricity, and the cause was generally attributed to the condensation of the skirts of an immense cloud by the rugged points of the hill with which it came in contact. The storm passed off in the direction of Worcester, and came on there with a tremendous fall of hail, or rather fragments of ice, measuring 5 or 6 inches in circumference, its course being marked with complete desolation. The Severn rose in one hour 6 feet, and continued to rise to the height of 20 feet ; the storm here was also accompanied with torrents of rain, continued peals of thunder, and vivid flashes of lightning." We are in- formed that the hail storm did great damage at Wor- cester, and that the windows of the Town-hall were battered to fragments. The Stipperstones is a ridge of rock, jutting out in numerous small points or edges, which, though they 81 act on the storm cloud as so many conducting points, are yet imperfect ones, and without any channel to carry the lightning to the earth : they therefore pro- voke the mischief, without any power to disarm it. Now, what security has that district against the repe- tition of the catastrophe ? None whatever : it may be a very rare event, and one far distant in the records of futurity, but the circumstance may also be the event of the present season or the next, for aught, at least, that we can tell, while a double line of paragreles planted on the summit of the ridge of Stipperstones would, in all probability, we may add certainty, pre- vent a repetition, and save that part of the country from such a tremendous doom. The preceding account may enable us to form some estimate of the extent of the nimbus, and of the mighty deluge of waters folded up within it the parent of those dread visitations which envelope the plain in one mighty torrent, cause the rivers to overflow their banks, and which, in a tropical clime, during the terrible monsoon, amid the loud and appalling acclaim of the thunder, raise the waters of the Ganges, and inundate the plains of Hin- dostan. The Jumna, we are informed by a friend, is very rapid before it enters the bosom of the Ganges, when it becomes turbid from the conflict of the streams. The average rise of the Ganges may be estimated at thirty-one feet, and the country is usually overflowed to an extent of more than one hundred miles in width. Eleven rivers blend their waters in this mighty stream, some in magnitude exceeding the Rhine, and none less than the Thames. The Ganges emerges from the Gangotri in the chain of the Himala mountains. Happy is the devotee accounted that perishes in its flood. We have, too, been informed of an immense mass of ice, which certainly fell in E ,5 82 India ; and though we must allow a little for the figures of orientalism, it is an undoubted fact that a mass of ice, of enormous magnitude, did fall in the Mysore. Our information was derived directly from an officer of high rank, long in India, and well ac- quainted with oriental literature ; being informed by one of the officers at the court of the Rajah, that, some years before, such an event had occurred in a village about thirty miles distant, he went thither, and satisfied himself of its truth from the independent tes- timony of several of the natives : it was described to be as large as an elephant, like crystal, burning their fingers when they touched it, and that in process of time it melted away. This is a phenomenon quite as diffi- cult as the meteoric stone relative to the theory of its formation ; and yet we do not believe that our earth is surrounded by a zone of such icy masses, floating in the empyreum ; and can as little imagine that it came from the moon, or the lesser planets, that wheel their eccentric orbits between Mars and Jupiter, still less from beyond Uranus, the planetary boundary of our system, as far as determined by modern astronomy. The following is an account of a continental storm, in the kingdom of Hanover, from the foreign journals : " On the 21st of June, 1828, at half past two o'clock, Hanover was visited by a hail storm : the hailstones were as large as ducks' eggs : every pane of glass in the direction of the wind, and almost every roof, was broken in : the icy masses were in the shape of a turnip, and weighed three to four ounces each: it lasted four minutes, and it was six hours after the storm had subsided before the fragments of ice had melted. All the windows in the city and suburbs were dashed to pieces : the streets were covered with lumps of ice to the depth of a foot ; the fruit beaten 83 off the trees, and the branches broken ; the birds of the air killed ; all the neighbouring gardens and fields laid waste ; many persons wounded ; cattle killed ; and the damage incalculable." At Joyeuse, in the department of the Ardeche, during the month of October, 1827, no less than 36 inches' depth of rain fell in eleven days, and on the 9th of that month 27 inches fell within two hours! This was attended by violent thunder and lightning. 84- CHAP. VIII. DESCRIPTION OF THE THUNDER STORM. PERSONAL SECURITY IN THE STORM. EFFECTS OF LIGHT- NING. PARALYSIS CURED MAGNETISM COM- MUNICATED. BENEFICENT MINISTRY OF THE THUNDER STORM. THE nimbus has already been described as the great theatre of the lightning. Before the thun- der-storm is announced, we shall perceive in the distant perspective horizontal lines, parallel to each other a kind of dense vapour plane ; this plane becomes still more dark and dense, arches of clouds rest upon it, the upper parts even and well defined, but dark and threatening at their base. Sometimes this aerial volcano seems to swell in magnitude by attracting other clouds in its vicinity, which appear to fall into it, while at other times it increases in magnitude without any such visible cause. At length the cloud is put in motion ; the thunders roll and the lightnings flash, and the rains descend, till, having spent its materials, the nimbus separates into frag- ments, which melt away in the aerial abyss, and dis- cover to us a serene sky. In reference to the electricity prevalent during a storm some years ago, Mr. T. Howldy of Hereford has communicated to us the following phenomena : " On my entering an upper room during a thunder storm, with Bennet's electroscope in my hand, the leaves suddenly diverged : on examination I found the electricity negative; a clap of thunder succeeded, and the divergent leaves in- 85 stantly closed ; immediately after they began to open again with negative electricity as before, and again collapsed with a peal of thunder. Subsequent to this the leaves diverged to their full extent, a loud crash was heard, but in this case the leaves still continued open ; in a few seconds after, however, they began to close, and the leaves remained finally shut." This crash terminated the storm, and the clouds dispersed. The last curious phenomenon, in all probability, is ascribable to electricity communicated by the discharge to the lower atmosphere, which, however, was gradu- ally dissipated. On the crash taking place, by which it appears a cow was killed in a meadow at some dis- tance, Mr. H. tells us, it was immediately succeeded by a peculiar rushing sound, the atmospheric wave being apparently reverberated in two or three reflux currents from the houses on the opposite side. The reverberation of the thunder is attributable to the irregular surfaces of surrounding objects; by means of these the sound is echoed, and sometimes often repeated. At sea, from the absence of surfaces re- flecting sound, it is, of necessity, more regular, de- creasing in its intensity, and finally dying away on the ear. The succession of sounds, therefore, presupposes the existence of bodies susceptible of reverberating sound ; and the loudness and duration will vary with the situation, distance, and nature of the reflecting surfaces, without any relation to the interval of time between the peals.* The same thing is observable in a piece of artillery when the discharge is made. When the sound immediately succeeds the flash, a single and peculiar explosive report, or crash, is heard, * It is a curious fact, that cock pheasants crow during' the thunder storm, at the close of the peal, and that they may be heard at a distance of two miles. 86 and in this case the discharge has occurred not far from the observer : the distance of the storm may be easily calculated by observing the number of seconds in the interval between the flash and sound. Lightning takes up a very limited period of time in its circuit, but sound moves at the rate of 1142 feet in a se- cond : thus, the number of feet multiplied by the seconds of lapse, would inform us of the distance, were the flash of lightning instantaneous like that of light ; but this is not the case, and it would only be the measure of danger as to the source of lightning in the discharge that has already taken place : but the focal cloud is still moving, ever changing its posi- tion, and even occasionally appears to be capricious. Sometimes we have thunder-storms recorded as occur- ring simultaneously in distant parts of the country, which would seem to indicate the electrified state of an extensive region of atmosphere. The lightning may be elicited from the atmosphere by the electric discharge, and the sound be the concussion produced by the recession of elastic shells of air, and their violent return to fill up the void occasioned by the explosive force. The opinion entertained by M. Biot respecting the light elicited in electric explosions and in lightning is almost that of Boyle that it was a distinct property apart from the electric agency- We are not altogether satisfied with Biot's view of the matter : thus we have deflagrated charcoal, silver, &c. foil, and ignited wire, in media of hydrogene, azote, &c., and in naphtha, and sulphuret of carbon. There seem to be two distinct kinds of lightning, a vivid flash followed immediately after by loud thunder like the sound proceeding from the discharge of cannon, and this is the most dangerous kind. The other has more extent of light, and is preceded by rolling thun- 87 der, and we have seen both alternate in the same storm. There is a difference not only in the intensity or vividness of the flash, but in the colour, sometimes it is bright, and at other times bluish ; and we remem- ber one night at Sion, in the Valais, that successive gleams of blue lightning were almost constantly dis- charged during the whole night, the intervals being scarce appreciable. The most powerful lightning is that which assumes the zig-zag form, called " forked lightning ; " which, while it shows a considerable con- centration, exhibits also the powerful resistance op- posed to its progress by the atmospheric air. The sheet, or silent lightning, is the quiet discharge from cloud to cloud, or the reflection of the lightning from the bosom of the cloud, which conceals the con- centrated point of discharge, and the non-accompani- ment of sound may be ascribed to the great altitude at which it takes place. Such certainly occurs in weather when the clouds may be supposed to have attained a considerable elevation. The most curious part of their history is, thaj they are always seen in the horizon, and lovely, indeed, are the coruscations which blaze on the cloud-capt summits of the Alps : the flashes are brightest when defined clouds make their appearance. The greater part of flashes of lightning are discharges from one cloud to another, having an opposite electricity, and the instances are comparatively rare when the electric fire strikes ter- restrial surfaces. In the last case it depends on a vast accumulation of power necessary to overcome the striking distance, as it is termed by the electri- cian, and its effects are proportional to the conducting character of the medium, and the concentration of the mass; in other words, to the resistance it meets with in its vivid progress to the earth, and to the difficul- 88 ties or facilities presented to its final escape into the ground. A fine copper wire may safely conduct it, while an iron wire might be dispersed into vapour; and if the former were a mere thread of wire, it might also be melted by the torrent of accumulated electricity. Occasionally the lightning ascends from the earth to the heavens ; we have only once Avitnessed a decided instance of this description, but so palpable that it could not be mistaken: the ascending lightning moved in a spiral form. We are informed that a similar phe- nomenon has been also seen : an ascending flash of lightning was observed to assume the cork-screw form, and to be evidently anticipated by one from above. In truth, there are peculiar phenomena on record which seem otherwise inexplicable, such as the trans- port of a mass of brickwork lifted bodily upwards, and carried to a distance : these may be connected with what has been called the returning stroke. In order to illustrate this, we may suppose an arch of electric cloud in the sky extending over a con- siderable surface ; if the lightning be discharged at one extremity of the arch, against some terrestrial sur- face, an electric ascent would simultaneously take place from the earth to the other extremity in order to restore the equilibrium : this last is called the " re- turning stroke." The following interesting fact was communicated to us by the Rev. Mr. : During a thunder storm in 1826, a tree at Acton, near Wrex- ham, the seat of Sir Foster Cunliffe, Baronet, was struck by lightning and shivered to splinters : two children of the reverend gentleman in question, with their nurse, were walking, at the moment, at some distance from the field where it happened ; one of these children was in the nurse's arms, while the 89 other walked by her side. When the crash super- vened, all were suddenly lifted up about two feet above the earth, and as suddenly let down again without the least harm. This may certainly be ad- duced as an interesting illustration of the returning stroke. The tree at Acton (an oak) was shivered to fibres, in some cases like beaten hemp, especi- ally the case in one specimen which we have seen. We have the record in the " Bulletin Universel " of an oak 15 feet high, 18 inches to two feet diameter at the branches, and three feet diameter at the root, having been struck with lightning : the top was dis- severed as by the stroke of a hatchet, and the trunk torn into a thousand pieces, and thrown to a vast distance ; and so complete was the destruction, as to be reasonably inferred that in certain cases the dispersion might be so complete as not to leave a wreck behind. There is a fact of very considerable importance, which we think ought to be attended to by gentlemen of estate, and landscape designers and planters, and in which the beauty of the picturesque, even at the expense of the beau-idealism of a Gilpin or a Price, should be sacrified to safety, and yet the sylvan " Venus " of the former may be prudently re- tained. In the catalogue of trees which have been singled out and destroyed by lightning, the OAK seems pre-eminent, and the almost exclusive victim sacri- ficed to its power. The oak should therefore never be planted near gentlemen's seats, or never apart from the main group, or clump or forest, or if it be, defended by the paragrele. The insulated oak sel- dom escapes under predisposing causes. It seems to be quite different with the Spanish chestnut. The patriarch tree of Etna, "Castagna delle cento cavalle ? " on the acclivity of that mountain, is a noble instance : 90 the lightnings of the volcano have often played around it, but it still remains unscathed. We also received another well attested fact of an ascent of lightning from the earth to the sky, in which several gentle- men were engaged in conversation during a thunder storm, in the open street, when the lightning visibly rose from before them and ascended. The thunder cloud is occasionally at no great elevation above the earth's surface. From the summit of some elevated mountain the traveller has often seen the lightnings play, and heard the thunders roll beneath the battle- ments of the rock. Massena and Souwarrow were engaged in battle on the St. Gothard, above the re- gion of the storm, while the lightnings flashed and the thunders rolled far beneath them. But in these high latitudes of ours, we can form only a faint picture of the terrible sublimity of the storms of tropical climes, truly terrible indeed are the lightnings which, in the monsoon and tornado, illuminate the sky and its sable canopy, and sublime and beautiful are the elec- tric flashes that gild with their reflected coruscations a Mont Blanc, and a Chimboraco. With respect to protection in the storm, it may be remarked, that when exposed in the open country, we must avoid seeking shelter under a tree, or by the wall of any building, and agreeable to the numerous observations we have made, such trees as are insu- lated, or stand apart ; for instance, those in the middle of a field, are more likely to be struck by the lightning than such as form part of the group of a clump or forest : streamlets, rivers, ponds, or other collections of water, are dangerous and may determine the light- ning, which would find a superior conductor in the vertical human frame, and its circulating fluids ; we must therefore retire from their banks : if the crash 91 succeed the lightning with no sensible interval of time, we are exposed to the most imminent and immediate danger, and our obvious and best security is to throw ourselves down upon the ground, and maintain a ho- rizontal position : being thoroughly wet will add to our safety, and if we can count from eighteen to twenty between the flash and succeeding peal, we are tolerably secure. It has been calculated that electri- city moves with a velocity more retarded than light ; and its movement is estimated at 1950 feet in a second of time : this being the case, we must deduct the movement of sound per second, from the sum in question, which is 114-2 feet; the remainder multi- plied by the number of seconds between the flash and the peal will determine the distance from the observer: let us suppose the interval is five seconds; then 1950-1142=808x5=4040 feet distance: the noise of the thunder is an announcement that the danger is over. The umbrella should never be used in a thunder-storm : when in the house we must not approach the fire-place, for the chimney lined with carbonaceous matter forms a tolerably good conductor. Last season a cottager was reading by the fire, the poker was inclined on the grate, and a dog was sleep- ing in contact with it ; the dog alone was killed by the lightning that descended by the chimney, and was conducted to the earth by the poker, while the man escaped, having received only an electric shock. In like manner the bell-pull must be avoided if attached by metallic wire *, for the lightning has frequently en- tered a house, pervaded the bell wire, and finding no escape to the earth has exploded here, burst through the window, and shattered a tree in the garden. In like manner all metallic objects whatever are to be * In modern furniture this is happily obviated. 92 diligently and studiously avoided ; even gilded mirrors and picture frames. We have lately been astonished to remark, in an instance where the lightning entered a building, the very extraordinary avidity with which it seemed to have run about, as it were in quest of some medium of escape from the premises ; the very nails in the floor were attacked, as well as those which had attached the laths to the ceiling and partition, the hinge of the door, and even a nail which fastened the head of a spade to its shaft was wrenched out, and imbedded in the wall : it appeared, indeed, to have ramified like " wildfire" and attacked every thing in the shape of metallic matter, with a fierceness quite surprising. The following details of the effects of a thunder storm attended by heavy rain which occurred at Lichfield on the 8th of May, 1825 or 1826, are sufficiently re- markable, and exhibit some wonderful phenomena in the history of this formidable power. About 3 o'clock p. M., as the family of T. W. Greene, Esq., of St. John's Street, were at dinner, a vivid and extensive flash of lightning struck the iron cap of one of the chimneys at- the south end of the building; slightly fusing the point of contact, and parting the brick work to the depth of about a yard, the electric fluid taking its course down the chimney, broke through the ceiling of the drawing room, where, passing down the frame of a large glass, it communicated itself to a marble chimney-piece, which it broke to pieces. It then forced a way by the side of the hearthstone into the dining room below, where it passed down the frame of a picture without in- juring the painting, to the chimney-piece, which it tore asunder with great violence ; projecting some pieces of mortar against a mirror opposite the fireplace with considerable force. In the progress of the electric 93 fluid down the sides of the chimneys, several smaller streams were occasioned by the different bell wires with which it came in contact. One of these ran along a bell wire in the dining room near the ceiling, and formed, by the fusion of the copper wire on the upper part of the wall close to which it passed, beautiful radiated streaks of a green and yellow colour, exhi- biting almost every variety of shade.* Another por- tion of the fluid attracted by the plate passed through a drawer in the sideboard, making a small hole in each side, continued its progress along the bell wire, and per- forated a nine-inch wall into a room containing a con- siderable number of pictures, along the frames of which it proceeded nearly all over the apartment, tearing the paper from the wall in several places, together with that of a small hand screen which stood upon the chimney-piece. A third division of the fluid passed through the china closet and forced the door-post from the wall ; ran down the bell wire to a bell in the passage below, where, finding no immediate conductor, it again perforated another nine-inch wall a short dis- tance above a small picture frame, down the side of which it proceeded toward the muzzle of a double- barrelled fowling-piece which stood in the corner of the room, ran down the barrel, and broke the stock into several pieces. The communication of the electric fluid to the house was accompanied by a tremendous shock and explosion, which shattered the beautiful mirror into a thousand pieces ; threw out nearly every pane of glass in the six windows of the dining and drawing rooms ; and swept down every article which stood on the table and sideboard. It left behind it a dense * We have seen a beautiful sketch in Paris, taken from a phe nomenon of this kind. 94 smoke and sulphurous smell which remained for some time. Mr. Greene and family were sitting round the table when the explosion took place ; and although several of them were thrown instantaneously from their seats by the severity of the shock, little personal injury was sustained. One of the servants, who was standing behind his master's chair, was struck to the ground with momentary deprivation of sense, and all present were in some degree for a time deprived of their hearing. The history of this remarkable visitation is ex- ceedingly instructive, traced from its entrance and through its progress t here is ample proof, if in- deed any were wanting, of the division of the meteor into streams or ramifications ; and a proof of the su- periority of numerous paragreles over a solitary con- ductor, as far as aggregated power can be enfeebled by multiplied division. Whenever the lightning was completely conducted by a sufficiency of conducting material, it passed harmlessly ; and even, it will be perceived, that mere superficial films, as the gilding of picture frames, accomplished this; evidence, as far as it goes, that electricity does not penetrate deeply ; a superficies of sufficient extent would therefore con- duct safely. The ramifications of its progress seem to have been determined by the scattered conducting materials on which it appears to have seized so vo- raciously, when there was found no continuous escape medium to the earth. In proportion to the resistance encountered will be the accumulation of power ; and in this case, by increasing the amount of resistance, it may be said justly of the meteor, " Vires acquirit eundo." So that a portion of lightning, which might at first be safely conducted by a small and solitary 95 wire to the earth, might ultimately, by increasing the obstacles to its descent and multiplying the means of resistance, have its power so magnified as to fuse and destroy almost every thing that stands in its way. This is a fact not imagined, but it is one of the very first importance, and will help to solve many phenomena, and tend to much practical good if duly appreciated. In all probability Mr. Greene's family were saved providentially from destruction by the abundance of scattered metallic matter as mirrors and plate, and bell wires and picture frames. On the 18th of June, 1829, a windmill was struck by lightning at Toot Hill, between Epping and Ongar. In this case the electric fluid entered by an iron band or bolt near the middle of one of the sails, and not at its summit : its destructive fury in the interior was de- termined by metallic materials. The chain used for raising the sacks was in part fused, the " links being found welded together in one solid mass" The electric matter appears to have been distracted from its pro- gress to the earth by several " half hundred and other weights standing on the floor on the western side of the mill: it here tore up a large space of the floor, and the weights were ejected to a considerable distance, and the boards forced off with great violence, and thrown in every direction." Such, it is stated, was ' the violence of the explosion, that a great many pieces of the boards and large fragments of the mill were thrown into the adjoining fields to an amazing dis- tance ; and some of them must have ascended to a great height in the air, as they were observed sticking up- right, in the hard ground, as if driven there by a pile- driver." In its last effort to overcome every obstacle opposed to its furious velocity, " it tore up the stones and gravel, and finally made its exit by forming a 96 large hole near the western side of the steps." In consulting the history of this record of destruction, the insufficiency of chain conductors, as formerly attached to the masts of ships at sea, becomes suffi- ciently obvious, as well as the danger of exposed metallic matter when not guarded by a superior con- ductor. The want of continuity occasioned its ra- vages : it never fails to seize on dislocated metallic matter with a fury which has no rivalry. Mr. Howldy of Hereford, an ingenious electrician, has by some novel experiments clearly proved the increased power of electricity, if retarded in its pro- gress : instead of using tubes of glass filled with water, as Mr. Woodward had done, he has employed a glass tube supplied with lamp-black ; also on breaking the continuity of the circle, by removing the chain of communication several inches from the exterior sur- face of the jar, and thus retarding the velocity of the discharge, he succeeded, with a very moderate charge, to kindle gunpowder, inflame camphor, tow, and even a fragment of cotton cloth : we have wit- nessed the repetition of these curious experiments in his hands, and can attest their complete success. Every thing metallic must, therefore, be discarded ; females should even lay aside their usual work, as their needles and scissors might operate as attracting points. In one instance, we were informed, while a gentleman was playing on the flute at a window, the silver key of the instrument attracting the lightning, the instrument was struck to the ground ; and while the silvered mirror has been displaced from its frame, and found unfractured on the table, that frame has been shattered to fragments. In a house not protected by conducting rods, gilt mirrors, picture frames and mould- ings, gold and silver paper hangings, and bell wires, 97 with the furniture of the fireplace, are all principal objects in the lists of danger. Last season, a female was killed by lightning when about to enter the corfe attached to the shaft of a coal-pit in Staffordshire, and the shoe-leather was torn into fibrous strips, caused, apparently, by the numerous nails therein. The centre of the room and the middle story of the house are the safest parts ; to recline either on the sofa, or on the bed is advisable, and these are the most secure places ; for, besides the horizontality of the position, the insulation is so complete as to supply all the re- quisites of security stipulated by the laws which regu- late electrical phenomena : it is absurd to take refuge in the cellar, as some timid persons have done, for the lightning may ascend, and there are instances on record where the lower story has suffered, and the super- structure been safe. A medical gentleman told us that he once went into his cellar during a thunder storm, and there received a very violent shock. The effects of lightning are very terrible ; the agent is resistless ; the proudest monuments of human genius are in a moment levelled to the ground, or shattered to their base, hymadryad of the woods, the patriarch oak shivered to splinters, and the alpine rock rent into fragments, and hurled from its eagle eminence into the valley beneath. And yet this dread agent has a " still small voice " which bids the fluids rise and flow in animal and vegetable being, and enables the little aeronautic spider, suspended by his silken parachute, to ascend above the regions of the clouds : this, too, is the agent which, artificially applied, has made even the dumb to speak, as attested by Mr. Miles Partington *, and under the form of a flash of lightning, cured a * See Brande's Journal, vol. xvi. p. 187. 98 helpless cripple, as we find by referring to the case in the London Medical Journal : A person of the name of Yardley, blind for some years, in crossing one of the London bridges, during a thunder storm, in the sum- mer of 1 828, was struck down by a flash of lightning ; and this singular event appears providentially to have restored the sense of vision. The following was com- municated to us by a gentleman to whom the circum- stance was mentioned immediately after : it occurred in 1802, near Lyme Regis : "Three men, and a woman with a child in her arms, had taken shelter from a storm under a large oak tree, which stood in the centre of a field ; the men, however, after remaining there for a short time, made for a shed, which stood at the end of a field, but before they could reach it they heard a terrific crash, and on turning round, found that the tree which they had just left had been shivered by the lightning, and the poor woman killed on the spot ; the child, however, strange to say, not only escaped uninjured, but appeared to have received just sufficient of the electric shock to restore it to the use of its limbs, though it had been unable to walk for a length of time previously." One shall be taken and the other left. We have a recent remarkable instance allied to these cases, in that of the New York ship bound from London to New York ; this vessel was twice struck by lightning the second stroke effected a very extra- ordinary cure, of which the following are the particu- lars: A passenger, very old, was so much palsied in his limbs, that for three years he had never been able to walk above half a mile ; and after his embark- ation had never been seen to stand up for a single instant : however, soon after the second discharge of electric fluid, which took place near to where the poor invalid was lying, he was observed with astonishment, 99 parading the deck, which he continued to do for some time, as if he never had been ill : at first he lost his senses, but this did not continue long, and the cure was complete : he walked with ease all the rest of the voyage, had the entire use of his limbs when the vessel arrived at New York, and travelled on foot thence to his own residence." Not the least remarkable effect of lightning is the communication of magnetism to iron or steel : in this very account we have a similar fact stated, for some of the knives and forks in the ship were partially fused, and had acquired magnetic powers. The effect pro- duced on the magnetic needles was very remarkable, for although they we're all in the 'same room, the results were diversified; in some the magnetic action was augmented, in others it was diminished; in some it was destroyed, and in others the poles were reversed : and we also find in reference to the latter circumstance, that by a stroke of lightning, the magnetic poles in Captain Waddell's compass, as related by Dr. Franklin, were reversed. In the Transactions of the Royal Society, No. 157., p. 520., and No. 237., p. 57., is the following fact on record: A stroke of lightning passing through a box of knives communicated to them power- ful magnetism ; and Mr. Walker, in his Treatise on Magnetism, p. 10., mentions a fact similar in kind : " In the island of Jamaica, in the month of Septem- ber, 1792, one end of my house was shattered to pieces by lightning, which killed one young woman, and very much hurt another : in a part of the house that had received but little damage, a girl who at that time had stood close to the one that had been killed, took out her needles soon after ; the needles stuck all together in her hand so strongly, that she took the point of her scissors to separate them, and so power- F 2 100 fully were they and the scissors magnetised, that part of the needles stuck to them in different directions ; and they lifted up the remainder like a thread, each needle hanging by the end of another." We have also an account of the magnetic effect of lightning in the Annales de Chimie : it occurred on the 22d June, 1822, at Toulouse : " A tailor was sitting in a chair, near the conductor, through which the lightning passed: he felt no shock ; but next day, on taking a case of needles from his pocket, he found them so strongly magnetised, that they hung in groups of six or seven together: another case containing five needles was lying on a chimney-piece, twenty feet from the con- ductor ; and these were also magnetised." While the interesting science of electro-magnetism reveals to us the principles of these singular results, they will teach us the necessity of disposing of every thing of a me- tallic kind from our persons, and make us cautious in handling them.* We have heard of a flash of light- ning having struck knives and forks laid out in a dinner service on the table, and the lightning was seen to sparkle among them like the phenomena of the diamond jar, or that of a metallic chain when the electric dis- charge is passed through it. Truly important are the advantages subserved by the thunder storm, nor can we venture to calculate their amount; these, however, are more obvious than the rest : when there is an unequal distribution of heat, its beneficent ministry tends to equalise the tempera- ture, and restore that lost healthy equilibrium, which is so important a desideratum to the economy of * The death of individuals may not unfrequently have been determined by some such simple and unsuspected cause. It must not be forgotten, that when Professor Richman was lulled he had seventy rubles of silver in his pocket. 101 animal and vegetable life. In the South Seas, we are told, a change of wind follows in the wake of the thun- der storm, and in all probability this is a very frequent consequence, as it is a natural one, of its agency in a disturbed equilibrium of temperature, and its power to restore the equipoise ; and as there can be no doubt that a portion of nitrous acid gas must be formed in every thunder storm by a reversal of the chemical constituents of atmospheric air, as was found in an experiment of the Hon. Henry Cavendish, (who, by passing a series of electric sparks through a confined portion of this medium, obtained evident traces of the production of nitrous acid vapour,) and as nitrous acid gas is a most powerful disinfectant, the thunder storm will thus tend to destroy the noxious and deadly miasmata that ascend from the surface of the ground, or are diffused through the air. Thus we have reason to infer the presence of nitrous acid in the rain which falls during a thunder storm ; and from some peculi- arity in its effect, acid matter has been suspected in snow. Some have gone so far as to infer meteoric matter as present in all atmospheric precipitations. Ta some such cause may be attributed the prompt acidi- fication of beer, milk, &c. during thunder storms. Vegetation, after the thunder storm, seems to wear a more healthy glow, and lovelier livery, and the animal frame feels more elastic, braced, and lively ; when the seeds of disease are floating on the bosom of the atmosphere, these germs of morbid matter are decom- posed and destroyed : and when the frame of the atmosphere is disordered, it is restored again and reno- vated, its sickness is healed, and it beats a healthier tone than before. F 3 102 CHAP. IX. THUNDER RODS. THEIR ATTACHMENT TO BUILD- INGS, AND TO SHIPS AT SEA. THE PARAGRELE. INFLUENCE ON THE STORM-CLOUD. EXTENSIVE UTILITY. CHANGE OF CLIMATE. THUNDER or lightning rods are metallic bars attached to buildings, for the purpose of presenting a medium of escape to the lightning; which, when it strikes a building, seizes on the best conducting medium, and most direct passage to the earth, and if these are not provided for it, its vengeance is terrible, and will be felt. The question whether balls or points should terminate the conductor, was once stoutly contested : .points, it was contended, attract the lightning from a greater distance, and, as it were, invite the approach of the storm-cloud, which might otherwise pass by on the other side, or at least float over the spot harm- lessly: but it was overlooked, or forgotten, that light- ning exercises terrible powers on a blunted surface such as a ball, from the great difficulty opposed to its entrance by the resistance it finds under such circum- stances, facts known to every electrician, while there its conducting character by such superficial oxidation is utterly destroyed, while the summit may still operate partially and imperfectly as a point. Thus we know that iron or steel wire is made red hot, nay, fused and dispersed in vapour, when made the uniting wire of the galvanic circle, while copper wire, under similar circumstances, may not be sensibly raised in tempera- ture. Besides, we shall find these conductors, as they are called, often dislocated, sometimes linked together, and at other times fastened to the wall by iron clamps or staples, and, finally, instead of entering the earth, the extremities are left to dangle several feet above the surface, as if we wished the lightning to raze the building from the foundation. Iron is every way ob- jectionable as the material for a conducting rod, or to form any part of it ; and we exceedingly doubt the propriety, notwithstanding the high authority of M. Gay Lussac's opinion, of having the conductor formed of two pieces, and those different metals ; and above all, from the circumstances already stated, of having one of these pieces iron : we are still more surprised at the recommendation of fifteen iron wires being twisted together to form a " strand," and in order to prevent its rusting, each wire is to be well tarred separately, and when they are twisted together, the whole rope thus formed is to be tarred again : now the resinous composition tar, is an electric or non-con- ductor, and the (superficial) conducting portion of the 105 metallic rope is hereby made useless. The iron con- ductor attached to the New York already alluded to, and which is stated to have been three tenths of an inch in diameter, was fused throughout, and fell in melted drops into the sea. Dr. Fischer, as stated in the Bulletin Universel, mentions the case of an iron conductor attached to a powder magazine, having en- tirely failed, on several occasions, in preventing the explosion of lightning close by its side: he ascribes this to its having acquired magnetism he found it magnetic ! and we would ask, Is an iron conductor ever found otherwise ? certainly not. He asserts from his experiments, that iron when magnetised loses much of its conducting power for electricity ; while an individual of the name of Abraham, of Sheffield, states, on the contrary, that the conducting property of iron is increased by being rendered magnetic. We agree with Professor Brande, in the belief that it makes no difference either way, but must express our astonish- ment at the recommendation of the latter, to have all lightning rods of magnetised iron, as if it were not a matter of notoriety that every rod of iron the moment it is raised to the vertical plane acquires an instantaneous magnetic power, independent altogether of that which it would at any rate acquire by the stream of atmosphe- rical electricity constantly passing through it: hence Sir H. Davy's recommendation of the communication of magnetism to steel bars, by attaching them to light- ning rods. Where there are iron conductors already attached to buildings, it is extremely advisable to con- join with such a conductor a copper wire (double the thickness of an ordinary bell-wire), its entire length, entering the earth to some depth below ; thus would a most perfect conductor be conjoined: the expense would not exceed a few shillings, and its attachment F 5 106 to the iron conductor would not only preserve it en- tirely from oxidation, but it is probable, from rendering it, on a galvanic principle, more highly negative, that the conducting character of the copper would be thereby more considerably enhanced. The conductor of a building should be of copper annealed or softened, and finely pointed at the ex- tremity ; the stem may be half an inch thick, and its summit rise several feet above the highest part of the building to which it is affixed : the conductor should be attached by being threaded through wedges of baked wood, and when within a few feet of the surface of the ground glance off at an angle, and finally ter- minate in a well, tank, or some wet place beneath. If conductors are to be still employed we should recom- mend them in no case to be attached to the building, but planted apart from it ; and a hollow conductor, as exposing a double conducting surface, would be the greatest improvement it could possess ; the thinnest metallic shell would thus, in all probability, be far su- perior to the thickest solid metallic bar. M. Gay Lussac proposes to elevate the conductor from fifteen to thirty feet above the building ; but unless attached to a strong support, it would bend under its own weight : we confess we do not see any such necessity ; for though the experiments of Messrs. Romas and Charles go to prove that the efficacy of a conductor will be increased in the ratio of its elevation, it must not be forgotten that the resistance of a conductor increases with its length, and therefore we think it decidedly better to use two instead of one, where the extent of building requires it, and not to have the conductor longer than necessary : as to those conductors which terminate in several spikes at all angles with the ho- rizon, and those crowned with balls, surmounted with 107 points " like quills upon the fretful porcupine," as in the Botanic Garden at Liverpool, we doubt their pro- priety, though if they were attached to separate stems we should advocate their utility. Thus, for instance, Mr. Achard of Berlin found that a single pointed wire screwed into the centre of a circular piece of brass one inch and a half in diameter, produced a greater effect in transmitting electricity or its reception of it than nine similar points inserted into the same base ; the proximity of these points occasioning them to act as a concentrated mass approaching the character of a ball. The following seem requisite conditions in a good con- ductor : 1. A finely pointed summit to offer an unre- sisting entrance. 2. A sufficient length to anticipate, as it were, the descending electricity, and receive it on its summit before it could reach any part of the building. 3. A superior conducting power in the material of the rod to facilitate its passage to the earth. 4. A sufficient thickness to prevent its fusion, which we think, how- ever, will greatly depend on the resistance it has encountered in entering the conductor ; and, finally, a safe conduction to a well or moist surface below ground, As remote parts of extensive buildings have been struck by lightning at distances three or four times the length of the conductor, it is evident that its power is circumscribed in its influence, as may easily be be- lieved, and experiment seems to prove that this influ- ence extends to a radius double the length of the lightning rod ; that is to say, the influence of a good conductor attached to a tower 120 feet high will extend to a distance all around of 240 feet. While we should much prefer the conductor being attached to an insulated pole, altogether separated from the building it is intended to defend, we, at the same time, require that there should, in all cases, be more than F 6 108 one conductor, and in many instances, as in gunpowder magazines, the space hedged in by several : flanked by such a circumvallation, like the city defended by the redoubt or the bastion, an ample security would be provided against the attacks of the storm in the case of paragreles, however, a more multiplied array would enhance their safety, and it would be better to guard doubly the avenues of danger, than by diminish- ing the number of sentinels to incur even a possibility of risk, a perfect and absolute security is certainly attainable : we do not think it necessary to enter more at length into Mons. Gay Lussac's views of conductors, as they differ in many respects from our own, as may be inferred from preceding observations. We exa- mined in 1825 two attached to the extremities of the Maison de Force at Lausanne ; the conductor here was iron, with a gold summit : it entered the earth through a trough or box filled with charcoal, to prevent at this part the rusting of the iron, and finally landed in a well under ground. The conductor we are about to recommend is com- posed of four or more softened copper wires, formed into a fasciculus by copper rings ; these wires are separ- ated at top, and bent from the centre outwards, at about an angle of 4-5 with the horizon ; they are ele- vated several feet above the highest part of the build- ing, and are threaded through wedges of wood : at about two feet from the surface of the ground they glance off at an angle, and terminate below the sur- face in the moist subsoil: the wires should diverge here, to allow the more ready diffusion of, and form an escape for the lightning : this may be called the root of the conductor. The following plan, we think, will completely obviate the necessity of having a gilded summit, and may be conceived an interesting applica- 109 tion of the principles of Voltaic electricity : Let the wires below ground in contact with moisture pass through a cylinder of zinc or iron, before they diverge to form the root ; the copper wires will in this case always remain free from any oxidation. The diameter of each wire we recommend to be one fifth of an inch, which would give a circumference of three fifths to each wire, and an aggregate conducting superficies of two inches and two fifths. In this arrangement we have four points, and each point its respective stem : a pointed conductor only acts as one point, irrespective entirely of the size of its stem, while multiplied points act in the ratio of their numbers. The tower of a church * might be supplied with two such fasciculi diagonally, or at opposing angles: if the tower be 120 feet high, the influence of a conductor at this eleva- tion would extend to a distance of 240 feet in every direction, and if there are two of this length, the dis- tance apart and secure might be 480 feet. We doubt the propriety of connecting any of the metallic ap- pendages of the roof to such conductors, as from their superior altitude and eminent character as conducting media, such would be superfluous, and might distract the lightning in its progress. One of such conductors attached to a vessel with a single mast will be found a sufficient protection ; but in the case of a ship, there should be one attached to the main and another to the * In Catholic countries the bells are sometimes rung during a thunder storm. This attempt to frighten the spirit of the storm proved fatal in 1825 to several individuals thus engaged in a, bel- fry at Carcassone, in France. A few weeks before our visit to Lausanne, the cathedral of that town had been struck with lightning, and considerably damaged. Indeed, it must be evident that the most dangerous place during a storm is the tower of a church. 110 mizen mast ; and from their flexibility, their fixation, it is presumed, would not interfere with the operations of the ship : we would further recommend that the united wires pass through a wooden cylinder, glazed inside with shell lac, and inlaid in the deck : the ex- tremity of the wires being brought at length in contact with the copper sheathing. It has been usual to attach metallic chains, and these only occasionally, to the mast; but such are hazardous appendages, as the lightning would find considerable resistance in descend- ing by these links ; since it is known that if we pass the electric discharge through a chain, an explosion and oxidation takes place at each link of that chain. In conductors formerly attached to the masts of ships, a spindle was employed, and this, connected with a chain of eyed rods, passed overboard by the deck into the sea ; yet even this inefficient apparatus was erected merely on the approach of a storm. Chains are in such cases improper, and this we made the subject of direct experiment. It is well known that if a metallic chain be laid on the surface of paper, and the electric ex- plosion passed through it, each link will display a cor- responding impress of oxidation. By attaching threads to several of these links in a circle, and imbuing them with a small portion of phosphorus dissolved in sulphuret of carbon, the heat communicated by the electric explosion was sufficient to cause ignition : each star of light which is kindled in our luminous experiments is a perfect miniature combustion. In vacuo fusion and oxidation do not supervene, wires being merely split into fasciculi of minute fibres. Mr. W. S. Harris's plan, certainly better, consists in at- taching to the spindle, which surmounts the mast about three feet, a strip of copper, three to four inches broad, and one eighth of an inch thick, by Ill means of metallic nails, its entire length, from the truck of the top-gallant mast, finally passing through the keel-stone and keel, by a copper bolt, into the water. Lieutenant Green appears to have called in question the utility and efficacy of lightning rods alto- gether ; but this opposition, as far as we can discover, rests on an entirely erroneous and false estimate, founded on the phenomena presented by conductors, as they are called, but which is a complete misnomer : the material is any thing but what it should be, while its construction is a complete violation of the known laws of electricity : moreover, the influence of the best conductor cannot be expected to circumscribe an unlimited sphere, for this were surely an unreasonable deduction, though it appears in many cases to be taken for granted. Let it be remembered that the number of tolerable lightning rods in the three kingdoms is extremely limited, and we have personally inspected the greater number of them. Thus have we seen, spindles or metallic rods erected on the extreme chim- neys of a house near to Derby a most dangerous ornament, for they cannot surely be intended as con- ductors. The lightning struck the Corsewall light- house, but fortunately did little damage to the building : the bell-wire having a fortunate continuity with the earth seemed its principle of immunity. A conductor had been erected, but when we saw it, it had no com- munication whatever with the ground : here it is in- dispensable (being built on a rock) that the conductor should be carried into the sea, and a plate of zinc be employed to prevent its oxidation. On our complain- ing of this circumstance to Mr. Stevenson, the civil engineer, he informed us, he believed this neglect had been since amended. No lighthouse should be without lightning rods on their most approved con- 112 struction. Lieutenant Green's proposition, we suspect, will not find an echo in any one at all conversant with practical electricity : according to his plan, a spindle attached to the mast-head is to be continued down to the cross trees, where it will " spit out " into the air! Valeat quantum, fyc. The term paragrele implies that it is a safe-guard from hail, as paratonnere signifies a protector from the thunder storm. The paragrele is intended to disarm the storm-cloud of its vengeance, by with- drawing its electricity, or altering its electric character, and thus prevent the precipitation of hailstones or fragments of ice (for they sometimes rather resemble the latter character), and we have stated that the form- ation of hail is an electric phenomenon. It is even so with the thunder-rod, which disarms the lightning by presenting a medium of escape to the earth : these depend on the same principles, and must necessarily stand or fall together ; both may be said to destroy or modify the structure of the storm-cloud, and of course its contents are either softened down to harmless pre- cipitations, or prevented from falling by the solution of the thus attenuated and diffused cloud, in the am- bient air ; for the intensity of the included electricity will have a reference to that of the lightning which flashes from it, or to the destructive density of the rain and hail which fall. A storm-cloud is more dangerous as its electricity is concentrated ; and in proportion as this electricity is withdrawn by points, the more diffuse and attenuated it becomes, and of necessity more harmless. A storm-cloud may be considered a natural Ley den jar, or electrical battery. We calculate that each paragrele should not cost more than Jive or six shillings, and agreeably to a re- mark we have already made on lightning rods, and 113 which equally applies here, they must be planted twice their length apart. If they are 35 feet long, then the distance between the paragreles should be 140 feet, allowing a radius of 70 feet to each, and if 50 feet long, they should be planted 200 feet apart. Mons. Crud, of Massa Lombarda, places them even 4-50 feet apart, but this distance is, from our preceding observations, evidently too great, unless their length exceeded a hundred feet. Paragreles are extensively used in Italy, Switzerland, and France, to preserve vineyards and corn fields from the destructive effects of hail storms ; the opposition they have met with is grad- ually subsiding ; hostility to their erection is rebutted by the powerful argument of their successful agency, and their erection generally extending: superstition has indeed regarded them as opposed to the providence of beneficent heaven ; we must, however, leave ig- norance to contend with the cloud which bounds her dark horizon, and suffer her to brood over her imaginary ills, or combat the spectres that haunt her vision, re- joicing that our mind is happily of a different tempera- ment. The storm-cloud is bounded by laws and lines of demarcation which it cannot violate : the seal of the omnipotent fiat, appended to the interdict, " Hitherto and no further, and here shall thy proud force be stayed," remains entire, and the investigation of these laws may lead us to a practical estimate of their principles. Prior to this happy application of scientific truth, the only method of warding off the devastation of hail storms consisted in dispersing the coming cloud by the discharge of cannon from the mountains. The following is a more questionable method of protec- tion : " There was a magical and superstitious use of these sweete-water-tortoyces agaynst hayle ; for if a man take one of these in his right hand, and carrie it 114 with the belly upwards round about his vineyard, and so returning in the same manner with it, and after- wards lay it upon the backe, so as it cannot turne on the belly, but remaine with the face upward, all manner of clouds should passe over that place, and never empty themselves upon that vineyard." * It appears that paragreles were attempted in America on the principles of Dr. Franklin, in the year 1819, and with boasted success. They have passed from the New into the Old World, and now prevail on the continent of Europe : in its original form it consisted of a pole sur- mounted with a point of brass ; from its lower extrem- ity proceeded a straw rope, with a strong linen thread twisted throughout its extent, founded on the fact Sig. Beccaria had discovered that a linen thread would conduct electricity, and it is even used to suspend the pith balls in our electroscopes; while Volta proved that straw was a conductor, and such is used in the electroscope that bears his name. The figure in the frontispiece represents the paragrele in its most im- proved form, and as it now used in the Canton de Vaud, the Bolognese territories, the Lombardo-Venetian king- dom, &c. Mons. Crud has the merit of having estab- lished them in the Bolognese territory, Bel tram i in Lombardy, and Professor Chavannes in the Canton de Vaud ; and we had the pleasure to discuss the merits of the question with the latter, who was gratified with the decided opinion we expressed in their favour. Professor Chavannes had encountered great opposition and hostility. The paragrele which has been figured and described is that recommended by Signor Orioli, Professor of Natural Philosophy in the University of Bologna. * The History of Serpents, &c. Topsell, London, folio, 1608, p. 287. 115 Pinnanzi of Mantua, as early as 1788, proposed the erection of numerous metallic points in the fields, for the purpose of depriving the clouds of their electricity, and thus preventing their resolution into hail. Many savans entertained the proposal as exceedingly plausi- ble, especially those of the academies of Dijon and Arras : similar opinions had been sustained by Gurnard, Buissant, Morveau, Berthollet, and since that period by Bosc and Le Normand. A few years ago, M. L'Apostolle of Geneva endeavoured to modify the erections proposed by Pinnanzi, by the substitution of straw ropes only ; but these were found to be insuffi- cient, and had fallen into discredit and oblivion, when Monsieur Tollard, of the College of Tarbes, in France, in the department of the High Pyrenees, revived them in a modified form : his plan was to erect poles of wil- low, poplar, pine, chesnut, &c. armed with sharpened brass points, attached to a rope formed of ripe barley or rye straw twisted throughout, in the manner re- commended by Sig. L'Apostolle of Geneva, and con- tended that he had thus succeeded in securing a ter- ritory of ten Communes. These interesting erections have been attacked and defended in France, Switzer- land, and Italy : the Nouvelliste Vaudois, of August 16th, 1825, very wittily observed, " Les paragreles n'ont que bien tenus : on les attaque partout a Paris, a Berne, a Zurich. La grele seule les epargne" Not- withstanding, however, the opposition which the para- greles have met with in France, we find a recognition in their favour in a formal report presented to the government of France by the Linnaean Society of Paris, recommending their universal adoption. * We shall now select some examples of the pheno- mena they present, and their successful application. * Rapport sur 1'Utilite des Paragreles, &c. Paris, 8 vo. 116 Sig. Perotti, of San Giovanni di Cassara, informs us, that having planted paragreles on an extent of 16,000 perches, he found that his corn fields and vineyards had sustained no damage, though fourteen storms had passed over them, and fell in full fury on the neigh- bouring lands of Valvasoni, Baguarola, and Savarganno. In the Gazzetta di Bologna, of the 17th of July, 1824, we are presented with several very curious phenomena connected with paragreles, and communicated in a letter, addressed by Dr. Joseph Astolfi, to Professor Orioli. On the 19th of June, 1824, a hail storm, accom- panied with thunder and lightning, came from Benti- voglio, opposite Altedo, and its route was marked with devastation, but when it approached a district supplied with 50 paragreles, the storm-cloud became singu- larly modified, a trifling quantity of hail fell about the outer line of the paragreles, but between the second and third line it fell of the consistency of snow. This tempestuous cloud, which arose from near Bentivoglio, moved on in another direction, and so soon as it arrived at the property of Count Chenef, protected by para- greles, it was suddenly dissipated, after destroying the intermediate country in its progress thither. On the 24-th of June, 1824, a stormy cloud from the vicinity of San Pietro, in Cassale, rose about ten o'clock A.M., it directed its progress towards the duchy of Galiero, destroying with hail the lands over which it passed ; here, however, it encountered a " park" of paragreles, on an extent of about 10,000 acres. The hail ceased at this point, and snow alone fell: continuing its movement, the storm-cloud finally encountered, in the commune of Altedo, the district supplied by Dr. Astolfi : it seemed now to be greatly agitated, was observed to sink considerably, and, finally^ to vanish away, after a fall of rain. We find also in an official notification to the Milan government, by the 117 Gonfaloniere of San Pietro, in Cassale (Signer Grandi), that during a severe tempest of thunder and lightning, he went out to reconnoitre the effects of the para- greles, and observed the electric fluid playing round their summits in graceful curves (courbes gracieuses), while in the adjoining fields the lightning did much mischief. Letters of a still later date, state that a line of storm-clouds formed beyond the districts supplied by Messrs. Bruneti, Astolfi, &c. no sooner approached the paragreles than they sunk to a lower plane, lost the peculiar colour, which the peasants know from costly experience is the feature of a severe storm, became white, precipitated snow, and finished in a shower of rain. A report on the paragreles has been made to the Academy of Sciences, at Paris, favourable to them, and even a society of assurance against hail is already founded on a belief in their efficacy. By order of the Sardinian government, the Royal Society of Agricul- ture of Turin appointed a commission to enquire into all that had been said or done on paragreles. 14-67 paragreles, it appears, were placed near Chamberry, on a chain of mountains from their base to their summit. On the 5th of August, 1825, a violent storm took place, which extended exterior to the pale of the paragreles, but no hail fell among them ; beyond their sphere, however, both hail and thunder were abundant. It appears, also, that on the llth of No- vember, 1825, a proprietor who had only four para- greles, each 22 feet high, saved his lands from a violent storm which fell on his neighbours. Mons. Baron Crud, in a letter to Professor Cha- vannes, dated 19th of July, 1824 *, observes, that in the preceding month a storm-cloud appeared, toward, even- * Feuille du Canton de Vaud, p. 277, &c. 118 ing, to stretch itself over the paragreles, and was attend- ed with frequent lightnings, and altogether formed an undulating horizontal line. It finally rose into the higher regions, none of it extended towards the earth, and he observed that the lower regions of the air seemed to be deprived of their electricity. On an- other day, he continues to remark, a hail storm fell in the territory adjoining the paragreles, a sprinkling of small hail fell at the first line of paragreles, but none whatever beyond that point. On two several oc- casions, he adds, it was observed by the country people, that when the storm-clouds approached the paragreles, they parted in sunder and passed by on each side. All these taken together form such a host of evidence as to be irresistible. When in Switzerland, in 1825, we every where received confirmations of their complete success, nor could we find a solitary proof of a single vineyard or corn-field throughout, sup- plied with paragreles, at all injured by hail storms ; but, on the contrary, a few miles from Neufchatel, where, from superstitious motives, paragreles had not been erected, the vineyards were totally destroyed by hail, while those supplied with them were wholly un- injured. We must, therefore, reasonably infer that these extraordinary exemptions from destruction are the purchase of this practical application of scientific truth. The shielded districts were in the very tract of the storm-cloud, nay, it passed over them harm- lessly, or if it halted in its progress, or hovered over them, its depositions were of so soft and mild a character that they were powerless. We in this coun- try can form no conception of the dreadful devasta- tions occasioned by hail storms on the Continent. Incorporated societies are formed for the express ob- ject of insurance against hail storms ; but we venture H9 to predict that, on the paragrele being universally adopted, an epocha not very distant, such companies will be found unnecessary, and already an immense zone of paragreles protects the territories that skirt the line of the Po. A gentleman of Bath informed us, that a circum- stance occurred about three years ago, when he was in the Canton de Vaud, which seemed to militate against the beneficial effects anticipated from the employment of paragreles. We can perceive no such inference as a legitimate deduction ; the case, however, is simply this : A hail storm precipitated its contents on a vineyard supplied with paragreles, each paragrele being the centre of an accumulated heap of hailstones, and the central one being the highest point of the vineyard, there appeared to be a greater accumulation round it than about the others. Now these very interesting phenomena, so far from proving the inefficiency of the paragreles prove to a demonstration their complete power over the storm- cloud, and that they can force it to yield up its tem- pestuous contents, and disperse its cearment to the four winds of heavens. In this case, too, it appears, the group was an insulated one, and that the numbers were few. We think that in the Canton de Vaud, the paragreles are too far apart and scattered ; and the mountain ridges, as at Vevey for instance, improperly neglected. Had the paragreles in question been multi- plied and extended, it is evident the frozen materials would have been proportionally diffused and attenu- ated to utter harmlessness. Now this precipitation did no harm to the vineyard, and who can tell but it might have been as destructive, otherwise, as any upon record. Fragments of ice might have been sub- stituted for harmless hailstones ; and but for this preci- 120 pitation, determined by the paragreles, might have laid waste the entire crops of the canton : and if the higher mountain range had been supplied with paragreles, the storm-cloud would have been discharged there, and its descent on the vineyard been anticipated ; for these marshalled ranks of paragreles would, from their loftier elevation, have first caught and emptied the storm-cloud of its destructive missiles. All this would only prove, that they were not planted thick enough, or sufficiently extensive, but their influence in discharging the cloud is obvious ; and the external and circumferential line should be planted closer to- gether than those that fill up the circle. We shall now proceed to detail some theoretical illustrations of the action of the paragreles on the storm-cloud ; but were we unable to accomplish this, the testimony of fact would certainly command our vote in their favour, and facts will maintain their com- manding attitude irrespective of all theory. It seems clearly proved that hail is an electrical phenomenon, and it has also been decided that lightning rods have protected fields from the devastations of hail, while ad- joining fields have suffered ; and on this principle, a Mr. Williams, some years ago, proposed the erection of lightning rods in our own country; but we would much prefer an army of paragreles to lightning rods placed at great distances. The influence of the latter has been limited to a radius double the length of the conductor merely, whereas the multiplication of points, as in paragreles, and their short distance apart, supply every desideratum wanting in the other, not to men- tion the vast expense of lightning rods, which would completely preclude their adoption. If an insulated thunder rod can discharge the storm-cloud of its forked and fiery elements, and scatter its parts to the 121 winds of heaven, a fortiori, paragreles, or pointed metal- lic wires, infinitely multiplied, and extending over a vast surface, must exercise a power infinitely greater. By means of rain or hail the electricity of the cloud descends to the earth, and these are more violent in proportion to the electric power treasured up in the cloud, and the resistance opposed by the atmosphere. Hail and rain are therefore the conduit pipes by which this discharge and descent are effected, but these are very imperfect conductors ; and it follows that in presenting a superior conductor in the form of a point, the lightning will prefer a descent by such a channel, and thus the electricity which aggregated the cloud being with- drawn, it separates and dissolves ; a series of points therefore draw off the accumulated electricity in silent capillary streams, attenuated to their ultimate degree, and it hence follows, that the watery mass, in its cloudy reservoir, will experience a similar and con- formable attenuation, and ' then, of necessity, will follow its resolution into gentle rain, or its congealed counterpart, snow. It is a matter of surprise that extensive conducting surfaces are seldom, if indeed ever, injured by lightning ; and we suspect, when they are struck, it will be found to be connected with some point more elevated than the rest. The copper roofs, so extensive in their range, in the great dock-yards of Devonport and Portsmouth .arsenals and ar- mouries, suspension bridges, conservatories, gasome- ters, iron stores, cast-iron forges, iron bridges, and the like, are sufficient proof.* The most extra- ordinary evidence of this kind we ever saw, was that of the gunpowder magazine at Chester, which was * The death of two individuals at Malvern, who had taken shelter during a storm, is an apparent exception, but the iron roof rested on insulated pillars. G 122 actually roofed and surrounded by a cluster of iron spikes, for its safety ! we believe that this extraordi- nary arrangement has been since altered. These severally concur to prove that a multiplication of points, or extension of conducting surface, tends to attenuate and diffuse that electricity, which would otherwise in a dense and concentrated form, be mis- chievous in an eminent degree. Hence in large cities or towns accidents by lightning are rare, and when they do occur, are determined by some adven- titious circumstances. In these cases, the aggregate of chimneys supplied with fires, or lined with carbo- naceous matter, supplies the place of multiplied con- ductors. The destructive effects of this formidable meteor being reserved for the insulated mansion or the tree, or the solitary cottage. If an insulated rod be presented to a dense aggregate of accumulated electricity, it must enter in one united torrent ; but if this were supplanted by numerous distinct rods at a certain distance apart, it is equally obvious, that by affording so many distinct channels for its escape, its intensity and force would be subdivided in the ratio of their number. In the former case it is an unbroken wave, and in the latter instance parted into many fractions : united strength in the one, while in the other it is enfeebled by division. Suppose a small pail with water were appended to the conductor of an electrical machine, having an orifice too fine for the water to drop from it, we should find, on electri- fying this pail, that the water would be discharged in minute streams through the orifice in question. If we now present a point to the conductor at a certain dis- tance, sufficient to withdraw only a part of the electricity, in this case, the discharge from the pail would be diminished in the same proportion, and the 123 stream or streams will be still more minutely divided than before. Let us suppose, again, that several points are presented to the conductor, sufficient to effect at the former distance a complete and entire discharge of the electrified surface ; in this case, no water what- ever will flow from the vessel. A sponge saturated with moisture, attached to the conductor of an elec- trical machine, and thus operated upon, affords a very good elucidation of the storm-cloud, as affected by the paragrele ; and it explains, we think, in a very satisfactory manner, how that, though, beyond the periphery which embraces the field of paragreles, the rain may be violent, and the descending drops of con- siderable magnitude, or, being congealed, form hail- stones or fragments of ice, yet are modified into gentle rain or snow as soon as they come within the pale of the paragreles, and immediately over the central chevaux de frize, where a fasciculus of multi- plied points effects a complete discharge of the electri- city of the storm-cloud, and of course that of its aggregated contents determined by it. This theory of the paragreles we offer as one every way satis- factory to our own minds, and on this principle it was we contended for the utility of the paragreles from the moment we witnessed their application in Switzer- land and Italy. We shall now proceed to a very transient examin- ation of some of the chief grounds of tJieoretic opposi- tion to their utility, premising, however, that this is not, as a Frenchman would term it, " une question des mots" but one which must be determined by the voice of evidence, and the amount of facts ; and there is not a solitary failure that can be produced against them. The antagonists to the paragrele have asked what effect can be expected from brass wires of G 2 124 only a line in thickness *, attached to poles thirty-five to forty feet long, while the strongest bar of iron, properly adjusted, only acts in a radius of fifty feet? Our objections to iron, and the grounds on which those objections are founded, have been already stated, and a bar of iron may be thick enough, and (independent of its innate inferiority as a conductor, rendered still more so by oxidation,) at the same time vastly inferior to a very slender rod of copper ; moreover, the extent of the radius of influence has no relation to the mass of the conducting material but its length, while its conductibility will be paramountly influential. Were there only one paragrele, it might not withstand the accumulated force of the storm, but there being many, its electric power is divided into numerous minute ramifications, a fact which is proved in artificial electrical experiments. It is again contended that paragreles, to be efficient and successful, should prevent the accumulation of electri- city in the storm-cloud. Now this is not their character ; they would, it is true, prevent the form- ation of any storm-cloud above them, but these messen- gers of destruction come from afar : the cloud, long before its approach, has been already charged with electricity ; the paragreles simply withdraw, as so many capillary channels, that electricity on which its de- structive features as a storm-cloud depend. Passing over many trifling objections which have not the slightest pretence to legitimate influence, we may advert simply to that founded on the altitude of the clouds, which has been stated to be from 3000 to 10,000 feet ; how, it has been triumphantly asked, can a paragrele act upon or affect a cloud at this elevation? These individuals contrive to forget, in * A line may be considered as one twelfth of an inch. their blinded zeal, that the lightning of the cloud at this assumed elevation has often singled out a conduct- ing medium from among other diversified objects, and by it been conveyed to the earth ; and a human being, no lofty object surely, in the middle of a field has been selected by the destructive meteor for its victim. We have already adverted to instances wherein electric gleams have appeared at no great elevation on conducting points, and could add to their number by evidence collected both from ancient records and from every-day occurrence. We have stated, that during thunder storms the metallic points of the fire-arms in the armoury of the Tower of London have been noticed to glance with electric fire, and circumstances of a similar kind have been re- gistered. Pliny, Livy, Caesar, and others, record curious facts of this description : the most interest- ing ^circumstance connected with these phenomena we find in the last-mentioned author. In the month of February, toward the second watch of the night, a dense cloud suddenly approached, accompanied by a terrible hail storm, and in the same night the tips of the lances of the fifth legion seemed on fire. The pas- sage being extremely interesting, as at once confirm- atory of our position, that the hail storm is an electric phenomenon, and of the efficacy of the paragreles as to their receipt of the electricity of the cloud, (and para- greles, it will be admitted, are more elevated than were the spears of the fifth legion of Caesar's army,) we record it : " Per id tempus fere Caesar exercitui res accidit incredibilis auditu, nempe vigiliarum signo confecto, circiter vigilia secunda noctis nimbus cum saxea grandine subito est cohors ingens ; eadem nocte legionis quintae cacumina sua sponte arserunt."* In * Caesaris Com. de Bello Afric. cap. vi. G 3 126 the Abbe Bertholon's work on the electricity of me- teors*, we find the following very curious and interest- ing practical phenomenon : it appears that there has been from time immemorial, on one of the bastions of the Castle of Duino, situated in the Frioul, on the Adriatic Sea, an iron pike attached vertically to the wall during summer ; when the weather inclines to be stormy, the soldier that mounts guard examines the iron of this pike in presenting to it the iron-shod summit of a halberd, which remains there for the ex- press purpose ; when he perceives that the near ap- proach of the halberd causes the iron of the pike to sparkle much, or that there is on its summit a spark of fire, he sounds a bell near the spot, to give warning to those who are working in the fields, or the fisher- men on the sea, that they are threatened with a storm, and on this warning all return home. This most singular custom, it appears, has been the prac- tice for centuries, and how very easy would it be for us to establish such a faithful test of the approaching storm, where it might be especially beneficial, and save many lives ; as for instance, on the nearest coast to any fishing ground, such as the Isle of Man, Highlands of Scotland, &c. ? We would now earnestly recommend the general adoption of paragreles in Great Britain : one has been already reared on our suggestion, and its phenomena are singular and interesting. Withering and blighting blasts, and the torrents of rain that fall so partially in spring and autumn, and oftentimes with such " fell swoop ; " all these, and other meteorological phenomena, may be modified by conducting rods in the form of paragreles, and the result be of incalculable benefit. * A Lyon, 1787. 2 tomes. 127 Whatever changes the electric character and state of the atmosphere, the grand depositories of the storm- cloud, and all its icy and tempestuous contents, must necessarily operate in the amelioration and modifica- tion of climate ; and paragreles, judiciously distributed, may be expected to do all this and much more than imagination can conceive, or the mind's eye circum- scribe. Typhus fever, for instance, has its lines of demarcation, and sometimes pays its regular annual visit ; and bronchocele, again, is obstinately and perma- nently attached to particular places. To ascertain whether any, or what effect the establishment of paragreles in such lines and localities would produce, might be a question at any rate of curious interest, and we cannot tell, a priori, what might be the results : the phenomena are altogether involved in inextricable difficulty, and in our present state of knowledge none can venture an opinion, our data being quite insuffi- cient. Corn-fields, farm-yards, orchards, and gardens should be supplied with paragreles ; and particularly gentlemen's lawns and parks. Paragreles might be so disposed as to be at once ornamental and useful the clematis, rosa multiflora, passiflora caerulea, or the hop, scarlet trumpet honeysuckle, &c. might be entwined around them : they are required where in- sulated trees are detached from the general group, such being particularly liable to be struck by light- ning ; but above all, in the case of extensive ranges of glass, as conservatories, stoves, greenhouses, &c.; and we believe that, even in this country, the annual destruction of glass by hail storms may be fairly esti- mated at many thousand pounds, independent of the injury done to the exotics. Gunpowder magazines should be surrounded by a double line of paragreles : all G 4} 128 would be safe and secure within the circumscription of the charmed circle. The hop, on which so much commercial speculation is hazarded, and from which crop so considerable a revenue accrues in the form of duty, is a most preca- rious source of emolument to the grower, who has many enemies to contend with in the insect world, as well as causes that are unsuspected by him : the roots of the plant are subject to the depredations of a singu- lar species of moth, called the ghost, (Hepialus humuli, of Fabricius,) while a small beetle, the Haltica con- cinna, is particularly destructive, early in the season, to the tender shoots : but the grand question of the crop hinges on the presence or absence of aphides, termed " the fly ; " which has indeed been pronounced " the barometer that indicates the rise and fall of the hop-grower's wealth."* The presence of the aphis will entirely depend on some morbid change (else we are much deceived in our observations) in the plant itself, and these are linked together as cause and effect ; now this morbid change will be connected with corre- sponding mutations in the atmosphere, or a blight imported on the wings of the wind, by which the am- bient air is parched, while a crippled and diseased vegetation transpires from its leafage the saccharine exudation called " honey dew ; " and as the eagles will collect where the carcass is, so aphides congregate where the leaves are imbued with this morbid nectar. It is true, various opinions have been entertained on this question, and not a few individuals maintain that this honey dew is a secretion of the insect. If a dis- tinct electric change had not been in these cases the * Introduction to Entomology, Lond. 8vo. 4th edit. 1822. vol. i. p. 182. 129 often decided precursor of their presence, we might have closed with the opinion, but as the fact stands we cannot give up convictions founded on the repeated evidence of our senses. Last summer, in particular, we investigated the phenomenon with great care ; the weather had been parched and sultry for some weeks previous, and the honey dew prevailed to such an extent that the leaves of the currant, raspberry, &c. in the gardens, literally distilled from their tips a clear limpid honey dew, excreted from the plant, for the phenomenon was observable on those plants that were entirely free from aphides ; and so copious was it where these insects were found, that had their numbers been centuple they could not cer- tainly have been the source of supply : the question with us, however, was set at rest by applying a lens, having previously washed and dried the leaf by a sponge, for in this case the immediately excreted glo- bules became apparent. Our opinion is at complete antipodes with that of Mr. Major *, who has so singu- larly confounded the " honey dew " with the gummo- resinous excretion of the acacia glutinosa, the horse chestnut, and the tacamahac tree (populus balsamifera), including even the family of the cisti, and of course the cistus creticus, which affords the well known gum resin called gum labdanum, being obtained, occasionally we believe, by combing the beards of the goats that browse on the shrub in the island of Candia. Gum labdanum is collected by a kind of whip, formed of leather thongs in two rows attached to a handle. Tournefort, when in Crete, visited the district where the cistus creticus grows and the gum is obtained, and which the peasants collect by flogging the shrubs with * Treatise on Insects, Lond. 1829. 8vo. p. 17, &c, G 5 130 this instrument, from whence it is detached, and made up into lumps. If it be probable, and we think the inference evident, that an altered electric state of the atmosphere pre- cedes the appearance of the " fly " on the hop plant, and that their presence is the signal of disease conse- quent on a previous morbid change, there can be little doubt that erect copper wires attached here and there to the poles, in hop plantations, thus forming so many paragreles, might produce a beneficial effect, and act as a counterforte to those electric changes that operate so fatally on the hop-bine. Is it not a matter of noto- riety to the hop farmer, that, by a favourable change in the weather, the already threatened crop suddenly assumes a livelier and healthier livery, or, to use his own expression, "recovers;" while the aphides, on which all the blame is laid, without the lady-bird (coccinella) having thinned their ranks, as suddenly, disappears, as was their advent; when, to use the growers phrase, the hop plant was in the first instance " struck " by them ? The truth is, their nutriment has vanished, and their withered and blanched exuviae attest the circumstance. On the preceding remarks respecting the hop fly, a letter was addressed to the Editor of the Times news- paper, and we think it but fair to give it insertion in this place, together with the reply which it elicited from us. It may be added, that in the case of the leaves of the hop plant, such are not wrinkled by these as- serted punctures, whereas rugce and excrescences and contortions follow like inflictions, and under which the currant, lime, elm r &c. sometimes writhe ; but here the insect wounds the plant to form a shelter or pro- tection for its ova or larvae. In early spring, easterly winds prevail, and these are attended by what is called 131 a blue mist, or " blight ; " and in April we know that it often tells fatally on the early promise of the year. This is supposed to be the medium of transport of the aphides : whether it be so or not, it is certain the aphides make their appearance soon afterwards. Mr. White of Selborne gives us a very interesting account of a shower of aphides, observed on the 1st of August, 1785 : "At about 3 o'clock on the afternoon of that day, which was very hot, the people of this village were surprised by a shower of aphides : those that were walking the street at that juncture found them- selves covered with these insects, which settled also on the hedges and gardens, blackening all the vegeta- bles where they alighted. These armies were then, no doubt, in a state of emigration, and might have come, as far as we know, from the the great hop plantations of Kent or Sussex, the wind being all that day in the easterly quarter ; they were observed at the same time in great clouds about Farnham, &c. In the sultry season of 1783," says our author, " honey dews were so frequent as to deface and destroy the beauties of my garden : my honeysuckles, which were one week the loveliest objects that eye could behold, became the next, the most loathsome, being enveloped in a viscous substance, and loaded with black aphides." Mr. White then gives an opinion that the honey dew is a vegetable secretion, and his opinion is entitled to no little weight from the judicious caution he constantly exercises. Aphides make their appearance in a very peculiar state of the atmosphere, and in sultry weather : whence the election? and what link can be traced between this atmospheric peculiarity and their indivi- dual powers of secretion ? The atmospheric change is the invariable antecedent, and their rendezvous the sequence of this alteration in the aerial medium, o 6 132 More than one thousand aphides have been counted on a single hop leaf: the leaf is tinged by an autumnal brown, such as a withering blight occasions, and which we witnessed as particularly remarkable in two of our Siberian crabs. Toward the end of July the leaves recover, and forthwith the aphides decamp : now why do the aphides decamp, when the renewed leaves pro- mise a new and delicate repast? and how does it happen that the leafage begins to grow green again before they actually take their departure, and it is still varnished with the honey dew, if the excretion of the aphis humuli ? Such myriads as clothe the leaves of the hop would, like the migratory locust, eat up every green thing ; and yet these leaves remain and recover, from an innate principle. It is not doubted that aphides, like other creatures, must " eat to live ;" and if they are the authors of the honey dew, they must make the vital juices of the leaf their prey, and it would wither, and leave not a wreck behind ; yet that leaf remains entire. Now it may be naturally asked how these events should be contemporaneous ? The leaf grows green and vigorous, and the aphides depart; or is the extraordinary proposition to be entertained, that at a specific period of the year the aphis, which before secreted honey dew, now ceases to do so ? and this intermission is the period of the recovery of the hop. It must thus appear evident, that the question cannot be decided by a coup de main, as Mr. Rennie has attempted to do. The ghost moth, already referred to, is a curious insect, so called from its excentric flight, and the evening twilight when it exercises these manreuvres, rising and falling, and balancing ; haunting and hover- ing over peculiar localities or patches. The exuviae of aphides is sometimes the achievement of their ene- 133 mies ; the body of the insect being drained of its vital juices by a syrphus, which will even suck the young out of the body of the parent. The hemerobius pro- ceeds in the same way, and afterwards decks itself with the skins it has emptied, like Hercules and the lion's skin ; not however, as it would appear, from a principle of vain glory, but rather that of concealment, the better to effect its tiger ravages. The coccinella, or lady -bird, is another enemy of these defenceless crea- tures. In France the lady-birds are put under the imme- diate protection of the Madonna, for what reason it is not so easy to discover : they are thus called " Betes de la Vierge," or " Vaches a Dieu." In 1827, the shore at Brighton, and all the watering places of the south coast, were literally covered with lady-birds, migrating, in all probability, from the hop plantations, after having . slain " their thousands, and tens of thousands." PREVENTION OP THE HOP FLY BY THUNDER RODS. To the Editor of the Times. Sir, The price of hops being of considerable pub- lic interest, it appears to me that a very novel and extraordinary proposal, just published, for preventing the ravages of the hop fly, so much destructive to valuable crops, requires to be brought under the notice of those interested in the subject. The proposal is contained in A. Treatise on Atmospherical Electricity, by John Murray, F. S. A., &c., who traces the increase of the fly to the electric state of the air, and therefore recommends copper wires to be attached to the poles in hop plantations, " to act," he says, " as a counterforte to those electric changes that operate so fatally on the hop-bine." He founds his proposal on the supposition that these " electric changes " produce a disease in the hops, which causes them to emit honey dew from their leaves, and that this attracts the fly to feed on it ; for, " as eagles will collect where a carcass is, so aphides congregate where the leaves are imbued with this mor- bid nectar." But if he had observed all the facts with sufficient minuteness, he must soon have discovered that he was mistaken ; for the fly neither does, nor can, feed on the honey dew ; and if it did, it would prove rather beneficial than otherwise, by clearing it off from the leaves, whose respiratory functions it obstructs in the same way as treacle introduced into the lungs will obstruct the breathing of animals. The unquestionable facts are, that the hop fly (aphis humulus), so far from feeding on diseased plants, only selects the strongest and most healthy leaves and shoots, into the tender pithy parts of which it thrusts its beak (haustellum) which is longer than its body, and no more fitted for lapping honey dew than the bill of ^Esop's crane was for eating out of a shallow plate. The honey dew itself, which Pliny hesitates whether to call the sweat of the heavens, the saliva of the stars, or a liquid produced by the purgation of the air (His- toria Natur. p. 12.), is nothing more than the excre- ment of the hop flies, as has been proved by the most distinguished naturalists, including Reaumur, Bonnet, De Geer, Sauvages, William Curtis, Kirby, &c. Mr. Murray, in opposition to these, states that he found the honey dew on " plants that were entirely free from aphides," and " by applying a lens, having pre- viously washed and dried the leaf by a sponge, the immediately secreted globules became apparent." The latter phenomenon only proves, as it appears to me, 135 that the leaf had been previously wounded, perhaps by the beak of some aphis, and thence there was ex- uded sap, not honey dew ; the former, that the flies had abandoned, as they always do, the leaves covered by their excrements, unless these fell from flies on some over-hanging branch. I have now in my study a plant of the chrysan- themum (chrysanthemum artemisice folia Wilde), the young shoots of which have swarmed with aphides all the winter, and the leaves below them are covered with honey dew ; so that a piece of writing paper laid under a branch was in a few hours sprinkled all over with it. I tried the experiment of wiping it off from a leaf; but more was formed when it was protected from the aphides above. I herewith enclose you some of the flies, the paper, and the leaves sprinkled with honey dew, which I have, by means of a lens, actually seen the flies eject, as any body may readily verify who will take the trouble. These plain facts will, I think, demonstrate the value of Mr. Murray's proposal (originating in the popular, but mistaken, notions of blight), and may, as I trust they will, prevent hop planters from wasting their money on a visionary theory. Lee, Kent, Feb. 26. J. RENNIE. THE HOP FLY. To the Editor of the Times. Sir, Your number of the 4th of March contains an intemperate attack on me, by an individual under the signature " J. Rennie," and I am indebted to a friend for pointing out to me the article in question, 136 without which it might have entered unanswered the cloud of silence. I am disposed to doubt whether a newspaper medium be the proper arena for scientific discussions, though this may, in Mr. Rennie's opinion, be a sic itur ad astro, : I happen, however, to think differently, and am not anxious to court any such notoriety. In many cases I may neither see nor hear of such flippant remarks, and thus the absence of reply might wear the tacit resemblance of acknowledged error. Mr. Rennie seems to be wonderfully anxious to be considered an umpire in the domain of natural history ; but it may not be irrelevant to remind him that there are many others who have investigated its phenomena with as keen and scrutinising an eye as himself: for my own part, I cannot divine why lie should be so caustic and bitter against me, unless it be, indeed, that he finds me so obstinate in maintaining my opinion on the ascent of the gossamer spider, in con- tradiction to Mr. Blackwall's preconcocted idea, and echoed by him in Insect Architecture) which, so far from being unhinged by any thing said by these indi- viduals, is, on the contrary, confirmed by every day's observation. Now, it does occur, that in this very treatise on atmospherical electricity, that subject is, inter alia, discussed, hinc ilia lacrymce. I am no theorist, Mr. Editor : I have been a gleaner of facts all my life long in the harvest-field of science, and with unwearied assiduity endeavour to penetrate the hidden recesses of truth, guided by the lamp of experiment : others may think by proxy, but that charge, at any rate, cannot be brought home to me. Be it known, sir, I never denied that some particular aphides might occasionally excrete a substance analogous to honey dew, and for aught that I know it may be a morbid secretion in them, as diabetes mellitus is in the human 137 subject ; nor do I even doubt that ants may " milk " such aphides, as Major-General Hardwicke tells us he has actually seen them to do, and whose authority I should be the last to dispute. But unless your cor- respondent can prove that plants in no instance, or under any circumstance, transpire such a glutino- saccharine matter, and may not do so in the leaf of the hop, the question remains precisely as it was, and he is floundering in a cloud of his own creation. The tendency of Mr. Rennie's remarks is trifling with the hop-grower's calamity, instead of rousing him to an endeavour to avert it by an experiment as simple in itself as it is trifling in expense. A few shillings would be the amount necessary for making the experiment in an extensive hop plantation ; and at the end of 20 years the copper wires would be worth nearly as much as their original cost. So much for " the waste of money ; " but he had been using the lens, and this seems, too, to have been contemplated through a magnifying medium. You are not to be told, sir, that metallic wires had already been proposed as a support to the hop-bines on a principle of economy. The wires I have proposed would at any rate prove the hop-grower's safeguard against lightning, or the tem- pestuous contents of the storm-cloud, whether in hail or a deluge of rain ; and such a security is certainly no trifle. It cannot be denied, Mr. Editor, that a change in the atmosphere invariably precedes the appearance of the aphis ; and it is equally true and palpable that every such change depends on a modifi- cation of electrical principles. When disease preys on the vitals, whether of vegetable or animal being, the system is more than usually liable to such parasitic attacks, the phthiriasis is a sad example. On such plant? as " glory in their strength " and riot in all the 138 bloom and luxuriance of health, aphides are never found, I mean here, occasional visitations of aphides. It is only under particular circumstances that the aphis is found on the hop, and sometimes the period of sojourn is short and transient; changes in the atmosphere invariably precede their advent or migra- tion, and these are linked as cause and effect. These visits being only special, must, in all probability, be connected with some morbid change in the included juices of the plant, and such will be the invariable consequent on an electric mutation in the ambient air. This position remains the same whether the egesta.of the aphides be honey dew or not, and my recommend- ation of copper wires, on the principle of the paragreles, comes home as forcibly to men's business and bosoms as before. In the physical as well as political world, the weak is the prey of the strong. The aphis may pierce the leaf, whose juices are the produce of decay, and " drink its marrow up," and the coccinella, heme- robius, and syrphus, in their turn, chuckle up the aphides. It is quite amusing to think of Mr. Rennie comparing a sickly chrysanthemum, the young shoots of which have swarmed with aphides all the winter, at this period of the' year, with trees or shrubs luxuriating under the intensity of a July sun, and in extremely sultry weather. Groves of the poplar and willow in hot calm weather transpire from their leaves a clear liquid, which falls like dew. In orange trees it is saccharine ; glutinous in the lime tree ; in the fraxinella it is inflammable, while manna is secreted from the leafage of the ormus rotundifolia. The honey which the bee collects from the nectaria of the flower under- goes little or no chemical change by its transit through the body of the insect, and it may be the same with the aphis. In the second paragraph of Mr. Rennie's IS* memorabilia, we have an elegant illustration of the effect of this excrementitious matter on the foliage of the hop, and which is assimilated to the effect of treacle on the lungs. It seems, by his view of the case, that the aphis thrusts its beak, which it appears is haustellum in Latin, into the leaf, and then there follows an allusion to ^Esop's crane. By the way, it should be stated, that though the said beak is here assumed to be longer than the body, it is only some- times found so, its usual length being only one third that of the body of the insect. If its sucker be inca- pable of lapping honey dew, on what principle does it lap the juices of the plant, for the principle is the same ; or the ruby-crested humming-bird, and many others of the trochili, quaff the nectar of flowers ? I do not think, sir, I have any right to be arraigned before Pliny on this occasion, for I never dreamed that it was either the sweat of the heavens or the saliva of the stars ; indeed, I think we may easily dispense with such obsolete nonsense. His predilection for the other authorities is very natural, for to them he owes nine tenths of Insect Architecture. With these individuals, in general, the question was mere matter of opinion or probable conjecture, and I might array in juxtaposition an equal host on my side of the argument. The late President of the Linnean Society, Sir James E. Smith, drew the same inference from his observations that I have done, namely, that though honey dew might in some cases be proved to be the egesta of aphides, it might, in many instances, be traced to the plant itself. It was a notable and convincing expedient to send you, sir, a leaf and slip of paper imbued with the excrementitious egesta of the aphis ; and I should wish very much to know the extent of information it com- HO municated. On my part I beg, sir, to tender for the honour of your acceptance a copy of my Treatise on Atmospherical Electricity, of which the question of the hop fly only occupies three pages. It has been very handsomely received by the public; and though it may by you be found undeserving of the compliment passed upon it, " a very ingenious and very interesting little work," I trust you will find that it does not merit, even in the section selected, the rude and ill-natured attack of Mr. Rennie. I cannot doubt, sir, but your sense of justice will grant an insertion to this reply, and which has been causelessly elicited. To any counter remarks, I shall be for ever silent. I have the honour to be, Sir, Your very humble Servant, J. MURRAY. To conclude, such a formidable chevaux de frize of pointed electric conductors must be a far more effective shield of safety for our houses and lands than an insulated thunder rod, (which, as generally con- structed, is mischievous in an eminent degree,) besides being much less costly. The one in its best estate possesses only a partial agency, the other embraces a vast range, and is complete and efficient : the latter, in its perfect form, may shield the wing of a building ; the former encompasses the entire domain of our persons and property, and scatters, as it were, the salubrious elements of an ameliorated and chastened clime over our vegetable tribes, as well as our flocks and herds, imparting the softening influence of a better than Italian and insular clime, checking by a mighty counterforte the abrupt transition of its continual HI vicissitudes, and arresting the inroads of disease. So true is it that Omnipotent Wisdom, who " MAKETH LIGHTNINGS WITH RAIN," hath also, in the conducting wire, " PREPARED A WAY FOR THE LIGHTNING OF THE THUNDER." THE END. LONDON : Printed by A. & R. Spottiswoode, N e w-St rcet-Square. In I2mo. Price 7s. A GLANCE AT SOME OF THE BEAUTIES AND SUBLIMITIES OF SWITZERLAND, WITH EXCURSIVE REMARKS ON THE VARIOUS OBJECTS OF INTEREST PRESENTED DURING A TOUR THROUGH ITS PICTURESQUE SCENERY. By JOHN MURRAY, F.S.A. F.L.S. &c. &c. " This is a delightful little volume, which none will repent having pur- chased." Magazine of Natural History. '"A Glance at Switzerland ' is really deserving the notice of a traveller in that country. We can recommend it as containing a great deal of information and pleasant description." Monthly Review, July, 1829. " Mr. Murray is entitled to take an honourable place among the scientific travellers of the day." Edinburgh Literary Journal, April 25. " This is the work of a gentleman who has evidently travelled with a scientific and intelligent eye." Court Journal, May 2. " We have now given extracts sufficient to show the entertainment and instruction to be derived from this pleasant work." Gentleman's Magazine, 1st October. " This work is the production of a gentleman whose scientific attainments are of the first order; and, with an unpretending title, it is a most amusing volume, containing a great variety of information, and blending pleasing description with philosophic observation." Hereford Journal, 21st April. Printed for LONGMAN, REES, ORME, BROWN, and GREEN. Of whom may be had, by the same Author, A MANUAL OF EXPERIMENTS, ILLUSTRATIVE OF CHEMICAL SCIENCE. SECOND EDITION. In 12mo. Price 5s. boards. "This little volume contains a series of interesting experiments, intended to excite the attention of the yousg chemist." Annals of Chemical Philosophy. RESEARCHES IN NATURAL HISTORY. SECOND EDITION, WITH A PLATE. 12mo. 7s. boards. " The author of this little work has chosen some of the most remarkable phenomena in nature for description and illustration, treated with much practical knowledge, gained, it would appear, from extensive and patient in- vestigation." Magazine of Natural History. 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