Popular Science Monthly/Volume 2/November 1872/Miscellany
The Ground Connection of Lightning-Rods.—It is asserted, by all the later authorities on the subject of lightning-rods, that a proper ground termination of the rod is of the very first importance to its efficiency as a protection against accidents by lightning. The electricity of the cloud will select the easiest path into the earth, or, as it is technically stated, follow the line of least resistance; and it is to furnish a path less resisting than the building itself that the lightning-rod is erected. But it is not enough that the rod have a sufficient conducting capacity. The current must be able to leave it, at the place where it terminates in the ground, as fast as it passes along the rod, else there is an accumulation, or damming up as it were, in the rod, which, when it has attained a certain volume or intensity, will relieve itself with explosive violence; and thus the appliance becomes an actual source of danger to the building, rather than a means of protection. Mr. David Brooks, in an able paper on "Lightning and Lightning-rods," published in the August number of the "Journal of the Franklin Institute," says on this point: "I do not say that a greater proportion of buildings having lightning-rods are destroyed or injured than of those not having them, although those making careful observations do give that as a result of their statistics. I shall undertake to show that this difficulty consists in the defective connection of these plates with the earth, and also that with a proper connection with the earth they are almost, if not an absolute, means of protection." Says Prof. John Phin, in his admirable brochure on "Lightning-Rods and how to construct Them:" "Upon the perfection of the ground termination mainly depends the value of the lightning-rod. If this be defective, no other good features can possibly make up for it. And yet, so little is it understood, that a careful examination of a very large number of rods leads us to believe that fully one-half the lightning-rods in existence are defective in this respect, and consequently furnish but an insufficient protection."
All objects may be said to conduct electricity, but they vary greatly in their conducting capacity. Copper conducts six times as well as iron, and iron thousands of times better than water, and water again thousands of times better than dry earth. That is to say, a rod of iron, to have the same conducting capacity as a rod of copper, would require to be of six times the sectional area, while, if a rod or column of water were employed, it would require to be many thousands of times greater in sectional area than the iron, and dry earth again many thousands of times larger than the column of water. In connecting a rod with the ground, allowance has to be made for this difference in conducting capacity, sufficient earth-surface being joined to the rod to give a conducting capacity approaching to or equalling that of the rod. Otherwise the lightning discharge, unable to find a free passage into the ground, accumulates until the tension becomes so great that it bursts from the rod with explosive violence, taking the track which affords the readiest means of escape, and often doing serious damage in its progress.
Accidents of this character are by no means rare. Mr. Henry Wilde, in a communication to the Mechanic s Magazine, gives two cases of fire, resulting from the ignition of the gas by lightning in buildings where it left the conductor and took to the gas-pipes. In one instance, the discharge passed down a wire rope suspended by the side of a tall chimney, and, leaving the lower end of the rope, which was some ten feet from the ground, darted across a space of sixteen feet to a gas-meter in the cellar of an adjoining cotton-warehouse, where it fused the lead-pipe connections, and set fire to the gas. In another instance, that of a church, provided with a lightning-rod, a lightning discharge left the rod at a point in close proximity to the gas-pipes, ignited the gas in the vestry, and the church was consumed. In a third case, the discharge descended a rod on a church-steeple, and, when within five feet of the ground, left the conductor, pierced a wall four feet thick, and disappeared in the gas-pipe under the floor of the church. Sillimau's "Physics" gives a similar example, where, in a church in New Haven, the lightning has twice penetrated a twenty-inch brick wall at a point opposite a gas-pipe twenty feet above the earth, although the conductor, of three-quarter-inch iron, was well mounted, but its connection with the earth was less perfect than that of the gas-pipe.
It being established that the lightning will take the easiest track into the ground, it follows, from what occurred in each of the above cases, that the least-obstructed path was by way of the gas-pipes, with their extended ground connections. In the first example, although there was a lightning-rod on the chimney, the lightning took to the rope, and, instead of leaving it at the lower end for the rod, which was near by, found an easier passage through the air to the gas-pipes of the cotton-factory, which differed from the rod in having an extensive ground contact. The same was true in the other cases the gas-pipes furnishing a readier path to the ground than the rods themselves. On account of the great surface contact with the ground, which gas and water pipes present, it has been recommended that lightning-rods be connected with these, as affording an excellent means for the escape of the electric discharge. At first glance, this might seem a dangerous expedient so far as gas-mains are concerned, the accidents above mentioned pointing to the danger of setting fire to the gas. This accident arose from the use of lead-pipe in making the connections with the meter. Had the gas-pipe throughout been of iron or brass, nothing of the kind could have occurred. Unmixed with atmospheric air, gas will not burn, and it was only through the melting of the lead-connections by the lightning that the gas was liberated and then ignited. Brass or iron pipes would have carried off the discharge without becoming fused, no gas would have been liberated, and no fire could have occurred. Commenting upon these accidents, Mr. Wilde says: "In my experiments on the electrical condition of the terrestrial globe, I have already directed attention to the powerful influence which lines of metal, extended in contact with moist ground, exercise in promoting the discharge of electric currents of comparatively low tension into the earth's substance, and also that the amount of the discharge from an electro-motor into the earth increases conjointly with the tension of the current and the length of the conductor extended in contact with the earth. It is not, therefore, surprising that atmospheric electricity, of a tension sufficient to strike through a stratum of air several hundred yards thick, should find an easier path to the earth by leaping from a lightning-conductor through a few feet of air or stone to a great system of gas or water mains, extending in large towns for miles, than by the short line of metal extended in the ground which forms the usual termination of a lightning-conductor."
But in the country no such system of gas and water pipes is at hand the connection of the rod with the earth must therefore be made in some other way. On this point Mr. Brooks remarks: "Unless a hundred square feet of metal can be laid in the bed of a spring or body of water, I believe the building is safer without the lightning-rod." The advice generally given is to bury the lower end of the rod in charcoal or coke. Prof. Phiu says, use coke, not charcoal; and, "whether iron or copper is employed, it will be well to sprinkle the coke copiously with a strong solution of washing-soda, for the purpose of neutralizing any acids that might corrode the metal. If a trench ten feet long be sunk to the depth of permanent moisture, and filled to a depth of twelve inches with coke, it will be ready to receive the end of the rod, and will furnish a path for all the electricity that will ever tend to escape from the clouds to the earth."
Foul Air.—The condition of the air commonly breathed in the workshop and school-room is fairly indicated by the following statistics, the result of a large number of observations made by Mr. Richard Weaver in the schools and manufactories of Leicester, England: As carbonic-acid gas is usually the chief impurity in rebreathed air, being produced in large quantities by both breathing and combustion, Mr. Weaver takes it as the measure of aerial contamination, the amount present under ordinary circumstances enabling us to judge of the degree of vitiation caused by the other products of respiration and combustion. Setting out with the established fact that free or what is commonly called pure air contains, for every thousand parts, very nearly four-tenths of one part of carbonic acid, Mr. Weaver found in the air of a room where six persons worked at boot and shoe finishing, each person having 51 cubic feet of space, that the proportion of carbonic acid was 5.28 parts per thousand, or more than thirteen times as much as Nature, when let alone, allows. In another instance, where the air-space to each of fourteen individuals was 186 cubic feet, with fourteen gas-lights burning, the amount of carbonic acid, to a thousand parts of air, was 5.32. In a class-room of one of the national schools, and the science class-room at that, seventeen pupils, each with 200 cubic feet of space, were breathing an atmosphere containing 2.41 parts per thousand of carbonic acid, or six times as much as the air contains in exposed situations. In no case examined was the proportion of carbonic acid as low as one part in a thousand of air; the average in fifteen places being 3.14 per thousand, or nearly eight times as much as in pure air. It is hardly necessary to add that the provisions for ventilation, where any thing of the kind was attempted, were of the most imperfect character. But what may be effected by ventilation was strikingly shown in the instance of a boy's day-room in one of the national schools, where there were one hundred pupils, each with 236 cubic feet of air-space. The ventilators were placed in the roof, and, though very far from perfect, the air in the room contained only 1.16 parts of carbonic acid to the thousand, the lowest proportion observed in any of the fifteen cases examined. Mr. Weaver states that the atmosphere in several of the rooms was very offensive, and in every case a pleasurable sense of relief was experienced on entering the outer air. Large space, without ventilation, he considers of little avail, as it has no advantage over a small room except that the air is a little longer in attaining the same degree of contamination.
Careless Disinfection.—In cleansing and disinfecting rooms that have been occupied by persons sick with contagious diseases, mere exposure to disenfecting vapors is not enough to thoroughly rid the apartment of danger to future inmates. The floors and wood-work require thorough scouring with some disinfecting fluid, and the walls and ceiling should also be carefully cleaned. If the walls are covered with paper, nothing short of its removal will be effectual, as it unquestionably has the power of absorbing and retaining contagious matters, that are not reached by the ordinary processes of disinfection. And its removal is all the more necessary where several thicknesses are plastered on the wall, for then the deeper layers are quite beyond any possibility of being cleansed; and, apart from the danger of contagion, the presence of paste in such quantities, as several thicknesses of paper involve, liable in warm weather to ferment and decompose, and at all times furnishing a nest for hosts of vermin, is certainly most objectionable. That wallpaper does actually furnish lodgment for contagion, and the paste with which it is stuck on food for vermin, is proved by the following cases reported in the Lancet: The workmen engaged in stripping the paper from the walls of a house in Manchester, that had previously been occupied by persons ill with fever, nearly all came down with the same fever, although previous to their visit the house had been disinfected with chlorine and carbolic acid. In the Knightsbridge barracks, where numerous layers of paper and paste had been allowed to accumulate, the walls when examined were found to be literally swarming with maggots, that were leading a most flourishing existence while subsisting on the paste between the several thicknesses of paper. The practice of freshening the walls of rooms by covering up, instead of removing the filth, has become extremely common, hundreds of houses in this city being yearly rejuvenated in this way, to the serious injury, no doubt, of their subsequent inmates.
Trees and Rain.—A correspondent writes thus to the Bulletin of the Torrey Botanical Club: "The influence of trees upon rain and the general moisture of the atmosphere, which has been much discussed of late, receives a strong illustration from the island of Santa Cruz, West Indies. A friend who spent the months of February, March, and April last, upon this island, informs me that, when he was there twenty years ago, the island was a garden of freshness, beauty, and fertility. Woods covered the hills, trees were everywhere abundant, and rains were profuse and frequent. The memory of its loveliness called him there at the beginning of the present year, when, to his astonishment, he found about one-third of the island, which is about twenty-five miles long, an utter desert. The forests and trees generally had been cut away, rainfalls had ceased, and a process of desiccation, beginning at one end of the land, had advanced gradually and irresistibly upon the island, until for seven miles it is dried and desolate as the seashore. Houses and beautiful plantations have been abandoned, and the people watch the advance of desolation, unable to arrest it, but knowing almost to a certainty the time when their own habitations, their gardens, and fresh fields, will become a part of the waste. The whole island seems doomed to become a desert. The inhabitants believe, and my friend confirms their opinion, that this sad result is due to the destruction of the trees upon the island some years ago."
Poisonous Paper-Hangings.—In his valuable paper "On the Evil Effects of the Use of Arsenic in Certain Green Colors," published in the third annual report of the Massachusetts State Board of Health, Dr. Frank W. Draper gives the following, among other startling cases of arsenical poisoning from green-colored paper-hangings:
In 1862, a case of fatal poisoning under the conditions in question occurred in the suburbs of London, the victim being a child. The cause of death was made the subject of an investigation before a coroner's jury. In the course of the evidence, it transpired that the deceased was the last of four children who had died within a period of two months, under exposure to the poison contained in the paper-hangings of the room they habitually occupied. They had all been attacked in the same manner, the prominent symptoms being referred to the throat. The color was loosely applied, having no glazing. It was very deliquescent; at 50 it was quite damp, and the stain came off on the hand like paint. Three grains of arsenic were found in a square foot of the paper. The symptoms were attributed by the surgeon in attendance, Mr. Orton, and by Dr. Letheby, who made the post-mortem chemical examination, to arsenical poisoning.
But greens are not the only colors which contain arsenic, nor wall-paper the only fabric colored with arsenical pigments. A correspondent of the Chemical News, who is in a position to know, states that the French use the following-named pigments, containing arsenic, in calico-printing, and that they are equally suitable, and doubtless used, in the color of paper-hangings: Light scarlet pigment contained alumina, arsenious oxide, and aurine; scarlet ponceau contained carbonate of lime in addition to above ingredients; dark green, a preparation of aniline green and arsenious oxide; steam chocolate, and catechu pigment, both contained arsenious oxide. Hallwachs has demonstrated the presence of arsenic in red, as well as in green-colored wall paper.
Volcanic Dust.—The dust discharged at the last eruption of Vesuvius, though very heavy, was carried in one direction to a distance of twenty-five miles, where it fell in quantities sufficient to cause great annoyance to the inhabitants. It consisted of aggregations of crystallized quartz, dotted over with the magnetic oxide of iron. The grains were very uniform in size, and would pass through a wire gauze the apertures of which measured the sixteen thousandth of a square inch. By boiling in hydrochloric acid, the whole of the iron can be removed, and nothing but crystals of fine white quartz remain. Its composition is the same as that of the iron-sand which is found in the soil in some parts of the country round Vesuvius, and which is the product of former eruptions; the latter, however, contains a larger relative proportion of iron, and the grains show a water-worn appearance under the microscope. Neither of the Vesuvian specimens contains titanium, which is found in the magnetic iron-sand of New Zealand, which has most likely been ejected from the great volcano of Mount Egmont.
Transfusion of Blood.—Dr. Aveling reports in the Lancet a case where life was saved by the transfusion of blood, by what is known as the "immediate" method. The patient was a lady dying from hæmorrhage. Her pulse had become imperceptible both at the wrist and in the temporal arteries; the heart's action was very feeble, and steadily growing more so; she was insensible, with dilated pupils that refused to contract on the approach of a light; the extremities were cold, and the lips and face blanched. Blood was pumped, by means of a suitable apparatus, directly from a vein in the arm of a man, into a vein of the lady's arm, without exposure to the air, and in a duly-regulated stream. Some eight ounces of blood were thus transfused. As the operation proceeded, the pulse at the wrist became perceptible, the lips less blanched, and warmth returned to the hands. In a few hours consciousness returned, the patient took nourishment, and afterward fully recovered.
Habits of the Opossum.—We gather from the American Naturalist, for September, the following interesting particulars concerning the habits of the opossum: The animal is widely distributed in the United States. It dwells in hollow logs, stumps, and in holes at the roots of trees, does not burrow, but takes possession of holes that it finds ready made. Into these it will carry leaves—using its tail for the purpose—and provide itself with a comfortable bed, when bad weather threatens. It does not hibernate, but hunts its food at all seasons, is slow of foot, and not very wild. It will eat bacon, dry beef, carrion, any kind of fowl, rabbits, any sort of small game, almost all the insects, and fruits of every variety, being especially fond of muskmelons; and is eaten in turn by many people, the flesh being considered delicious. This has a flavor resembling that of the flesh of the young hog, but is sweeter and less gross. Negroes and others are exceedingly fond of it; dogs, however, hold a very different opinion, and will sooner starve than consume it. The animal is habitually incautious, and when attacked seems to possess little power of resistance; literally suffering itself to be eaten alive by the turkey-buzzards, while it lies on its side and protests against the proceeding by a succession of grunts. Exceedingly tenacious of life, it will survive a vigorous crunching by the dogs, when it seems as though every bone in its body had been cracked. Although sometimes found concealed under the floors of houses and out-buildings, it refuses to be domesticated, and is believed to dwell but a short time in any one place.
Dr. Carpenter against Materialism.—Dr. Carpenter, having been charged with attacking the philosophy of Profs. Huxley and Tyndall in his late address, replies, in a letter to the London Echo, as follows:
"Nothing was further from my intention than either to give a theological turn to my address, or to make any attack upon the philosophy of my two valued friends, whom I believe to be, in regard to most, if not all, of the philosophical questions I have treated, at one with me.
"But I did set myself to combat a mode of thought on scientific subjects which I know to be very prevalent among half-educated scientific men, who have never studied the constitution and working of their own minds, and which has been carried out most fully by a certain school of (so-called) Nature Philosophers in Germany. Of the tenets of this school, a small work by Dr. Buchner, entitled 'Kraft und Stoff'—Force and Matter—which has run through many editions, and has been translated into French, may be considered an exponent. The tenets are (I write from recollection, not having the book at hand) somewhat as follows:
"1. That we know, and can know, nothing of the external save matter, and the laws of matter.
"2. That these 'laws' are fixed, unchangeable, and self-acting.
"3. That there is consequently no necessity for a God, since Nature can do very well without one.
"4. That, if there be a God, he is limited in his action—just as man is—by the 'laws of matter,' which he can no more control than man can; and that he is, therefore, in his relation to Nature, only a higher kind of man.
"Now, my object was to show:
"1. That what we call 'laws of Nature' are simply our own expressions of the orderly sequence which we discern in the phenomena of the universe; and that, as all the history of science shows how erroneous these have been in the past, so we have no right to assume our present conceptions of that sequence to be either universally or necessarily true.
"2. That these so-called 'laws' are of two kinds, one set being mere generalizations of phenomena, of which Kepler's 'laws of planetary motion' or the 'laws of chemical combination' are examples, while another set express the conditions of the action of a force, of which the existence is, or may be, made known to us by the direct and immediate evidence of our own consciousness—our cognition of matter being indirectly formed through the medium of force.
"3. That 'laws' of the first kind (which we may for convenience term phenomenal) do not really explain or account for any thing whatever. Nothing is more common than to hear scientific men speaking of such laws as 'governing phenomena,' or of a phenomenon being 'explained' when it is found to be consistent with some one of such laws; though the fact is that the law is a law merely because it is a generalized expression of a certain group of phenomena; and to say that any new phenomenon is 'explained,' by its being shown to be in conformity to a 'law' is merely to say (as Prof. Clifford well put in his lecture) that a thing previously unknown is 'explained' by showing it to be like something previously known.
"4. That, on the other hand, every 'law 'of the second kind (which we may distinguish as dynamical) is based on the fundamental conception of a force or power; so that if the existence of such a force (as that of gravity or electricity) be admitted, and the conditions of its action can be accurately stated, then the law which expresses them may be said to 'govern' the phenomenon; and any phenomenon, which can be shown to be necessarily deducible from it, may be said to be 'explained,' so far as science can explain it. But the utmost that science can positively do, as I stated toward the conclusion of my address, is to demonstrate the unity of the power of which the phenomena of Nature are the diversified manifestations, and to trace the continuity of its action through the vast series of ages that have been occupied in the evolution of the universe.
"5. I expressed the opinion that science points to (though at present I should be far from saying that it demonstrates) the origination of all power in mind; and this is the only point in my whole address which has any direct theological bearing. When metaphysicians, shaking off the bugbear of materialism, will honestly and courageously study the phenomena of the mind of man in their relation to those of his body, I believe that they will find in that relation their best arguments for the presence of infinite mind in universal Nature.
"Now, the only expression I have ever met with, in our own language, of the philosophy which (as I have said) worships the order of Nature as itself a God, was uttered by Miss Martineau, in the book on 'Man's Nature and Development,' which she produced some twenty years ago in conjunction with Mr. Atkinson. Not having the book at hand, I cannot cite any passage from it; but I well remember the general drift of its argument (putting aside mesmerism, phrenology, etc.) to have been that, whereas mankind formerly believed the phenomena of Nature to.be expressions of the will of a Personal God, modern science, by reducing every thing to 'laws,' had given a sufficient 'explanation' of these phenomena, and made it quite unnecessary for man to seek any further account of them.
"This is precisely Dr. Buchner's position; and it seems to me a legitimate inference from the very prevalent assumption (which is sanctioned by the language of some of our ablest writers) that the called laws of Nature 'govern' the phenomena of which they are only generalized expressions. I have been protesting against this language for the last quarter of a century; and, as I know that Dr. Buchner's views are extensively held among the younger thinkers of Germany and France, and have reasons to fear their extension to this country, I thought it well to take the opportunity which has been recently afforded me of calling the attention both of scientific men and of the general public to what I consider the true functions of man as the scientific interpreter of Nature. It was not because I had any thing to say on this subject that would be new either to men of science or to theologians, who have already gone through a like course of thought with myself, but because I hoped to lead some to think upon it who have never so thought before, and to help others to a clearer view of it than they might have themselves attained, that I chose it as the topic of my address. And, so far as I have the opportunity of judging, my hope is being fully realized."
Artificial Butter.—At the request of the victualling department of the French Navy for some wholesome substitute for butter that would keep well, Mege Mouriez, after a long course of experiments, has succeeded in producing an excellent substitute for genuine butter, that does not become rancid with time, and is otherwise highly recommended. Experiments made with cows, submitted to a very severe and scanty diet, led to the discovery that they continue to give milk, though in greatly diminished quantity, and that this milk always contains butter; whence it was inferred that this butter was formed from fat contained in the animal tissues, the fat undergoing conversion into butter through the influence of the milk-secreting glands. Acting on this hint, Mouriez's process begins with splitting up the animal fats. Finely divided fresh beef-suet is placed in a vessel containing water, carbonate of potash, and fresh sheep's stomachs, previously cut up into small fragments. The temperature of the mixture is then raised to about 112° Fahr., when, under the joint influence of the pepsin and the heat, the fat becomes separated from the cellular tissue. The fatty matter floating on the top is decanted, and after cooling submitted to very powerful hydraulic pressure. The semi-fluid oleo-margarine is thus separated from the stearine, and becomes the basis of the butter to be afterward produced. One hundred pounds of this oleo-margarine, along with about twenty-two quarts of milk and eighteen quarts of water, are poured into a churn, and to this mixture are added a small quantity of annatto and about three ounces of the soluble matter obtained by soaking for some hours in milk cows' udders and milk-glands. The mixture is then churned, and the butter obtained, after being well washed with cold water and seasoned, is ready for use. If required to be kept for a long time, it is melted by a gentle heat in order to eliminate all the water.
Ventilation and Warming.—In a lecture on ventilation, lately delivered before the Franklin Institute, Mr. L. W. Leeds, after detailing the abominations he encountered in his examination of the ventilating arrangements of the Treasury Building at Washington, gives the following practical directions concerning provisions for ventilation and warming in the construction of buildings. First, never have long underground fresh-air ducts. Second, never allow a sewer, soil-pipe, foul-air flue, or smoke-flue, to come near the fresh-air supply-flue, for fear of some connection being made between them by carelessness or accident. Third, never heat a building exclusively by currents of warm air. Fourth, always put the heating flues on the outside walls instead of on the inside walls. Fifth, endeavor strenuously to avoid the fresh-air chamber becoming a common receptacle for all the rubbish of a filthy cellar.
Sardines.—Mr. N. S. Dodge has given a very complete and interesting account of the "Natural History and Preparation of Sardines" in Hearth and Home, from which we gather the following: In natural history the sardine is the young of the pilchard, a fish resembling the herring in size, but thicker. They get the name of sardines, from having been formerly found in great quantities off the coast of Sardinia. They make their appearance about the coast of the Armorican Peninsula early in spring, and succeed each other in countless shoals throughout the summer months. These shoals are marvellous for their size and the number of fish they contain. Each one takes the shape of a huge fish, bulging out toward the middle and tapering toward either end. The shoals vary from ten to thirty yards in width and from fifty yards to half a mile in length. The fish are sometimes so closely packed that numbers are constantly being shoved out of water. They are caught with nets, much in the same way as herrings, only the nets are provided with much smaller meshes. Although nets are employed, bait is also used. This bait is called rogue; and is imported in barrels from Norway.
In catching the fish, several boats go together, a man standing in the bow of each to give notice of the approach of a shoal. Upon the cry of "Voila!" the boats make for the head of the shoal, the nets are cast, and bait is thrown overboard. The fish in their eager pursuit after the bait get entangled in the net, when a second net is thrown out and the first one hauled in. When a boat is loaded, the fish are taken ashore and immediately sold. The process of preserving is as follows: As soon as the sardines are landed the greatest activity is necessary to get them "sain et sauf," since exposure to the air depreciates their freshness and much handling impairs their flavor. First, the fish are thoroughly washed and scraped, so as to free them from every impurity. They are then sprinkled with fine salt which crystallizes upon the surface and is almost immediately removed. Heads and gills are then taken off, a new washing undergone, and the fish laid to dry in the sunshine, on frames of wire or green withes. After drying they are thrown into caldrons of boiling olive-oil and cooked for two hours, when, after a second drying, they are transferred to the tables to be packed. Here women only do the work. To put the fish nicely in their places, to smother them with boiling oil, to fit the lid of the tin box, turn a jet of hot steam on the joints, and toss it hermetically sealed to the inspector, is but the work of a moment. Perhaps the one essential element in the curing of sardines is perfect olive-oil. If it be not entirely tasteless, it destroys what the Sardinians call the "aramato," the delicate, volatile flavor of the fish.
Sprats, shiners, roach, herrings, dace, and carp, when young, and with their heads off, have sufficient resemblance to sardines to pass for the genuine article. They are put up at various places on the southwestern coast of France, and are largely exported, probably comprising three-quarters of all that are sold in the United States under the name of sardines. When well cured, preserved in good oil, and hermetically sealed, these small fry are savory and palatable, but they lack the delicate volatile flavor of the real fish.
Ancient Engineering Among the Chinese.—The most remarkable evidence of the mechanical science and skill of the Chinese so far back as 1,600 years ago is to be found in their suspended bridges, the invention of which is assigned to the Han dynasty. According to the concurrent testimony of all their historical and geographical writers, Sangleang, the commander of the army under Baou-tsoo, the first of the Hans, undertook and completed the formation of the roads through the mountainous province of Shense, to the west of the capital. Hitherto its lofty hills and deep valleys had rendered the communication difficult and circuitous. With a body of one hundred thousand laborers he cut passages over the mountains, throwing the removed soil into valleys, and, where this was not sufficient to raise the road to the required height, he constructed bridges which rested on pillars or abutments. In another place he conceived and accomplished the daring project of suspending a bridge from one mountain to another across a deep chasm. These bridges, which were called by the Chinese writers, very appropriately, flying bridges, and represented to be numerous at the present day, are sometimes so high that they cannot be traversed without alarm. One still existing in Shense stretches four hundred feet from mountain to mountain, over a chasm of five hundred feet. Most of these flying bridges are so wide that four horsemen can ride on them abreast, and balustrades are placed on each side to protect travellers. It is by no means improbable (as M. Panthier suggests), as the missionaries to China made known the fact more than a century ago that the Chinese had suspended bridges, that the ideas may have been taken thence for similar construction by European engineers.