Expansion of Mineral Oils. MESSRS. EDITORS :—I inclose an extract from the Tkliovte (Pa.,) Journal, in relation to the paper of M. Deville, on the " Expansion of Petroleum," commented on, in your issue of 17th in St., by Prof.Vander Weyde and yourselves. The article, as it states,agrees in its conclusions with practical observations on from 10,000 to 30,000 bbls. of crude oil, in iron and wooden storage tanks, car tanks, and barrels : " A Frenchman, with the very aristocratic name of Henri Saint Claire Deville, has lately presented to the Academy of Sciences, at Paris, a paper—thp third of a series—on the ' Physical Character of Mineral Oils,' in which he mentions the increase in bulk occasioned by an elevation of temperature, as a prominent cause of danger by fire where petrolenm may be stored. Prom long experience, oil dealers in this country have come to be well aware of the fact of such expansions, although without, in most cases, any idea of its amount. This is odd enough, too, when we consider the constant use made of oleometers, measurers of the density of oil.' For this reason, the following remarks may not be inappropriate : " The scale of Saume's hydrometer, or oleometer, or densi-tometer, a wholly arbitrary one, represents for each degree within the usual limits of crude American petroleum,as nearly as may be, four and a half thousandths of the density of water at 60 Pah. As every increase of temperature of 10 Fah. equals a decrease in density of 1 B., the expansion of oil may be taken, without sensible error, to be '00045 of its bulk for each degree of Fahrenheit's thermometer. Allowance for expansion is always made in shipping oil, except in the old-fashioned wooden tank cars, where the oil is permitted to force its way through the hatches, roof, and sides of the tanks. In shipping in barrels, it is customary to leave about one gallon ' outage,' as in 50 (which may be considered the extreme variation in temperature likely to occur while the oil is in transit,) 44 gallons would become 45. It would be safer and more economical to allow yet greater room, were it not for the advantage, in that case, apt to be taken of the shipper by the consignee. The allowance for expansion in Empire Line iron cars is very large, consisting of a cylindrical dome, about 40 inches in diameter, and 30 inches high—the capacity of which is about 4 per cent of the whole car—50 of temperature representing an expansion of but 2 per cent, it is evident that these Empire iron cars are as safe and economical as they are convenient. The writer has no knowledge of the empty space left in the five gallon cans so largely used for exported refined, but 5 inches square by 1 inch high would be sufficient. " The increase in bulk, in the summer, of oil stored in iron tankage in winter,is of considerable importance in these times of high prices. A twelve thousand barrel tank is 60 feet in diameter,and 24 feet high", and holds in each inch of its hight 176256 gallons. The mean temperature of oil here in Tidi-oute is, in winter, about 20, and in summer 70—both very nearly. The range being thus 50, the volume of oil to each inch, at 20 Fah., is increased 39'66 gallons; but as the tank has, also, grown larger,this amount is not shown by measure. Iron expands '000006964 for each degree, or for 50, about three and a half ten thousandths; so that the circumference of the tank is increased '7917 of an inch—the diameter by 252 of an inch; and the capacity for each inch of hight by 62 of a gallon. Therefore the apparent gain is only 3904 gals, for each inch of the tank at 20. It is to be noted, however, that no allowance is here made for the fact, that the temperature of the tank is always higher or lower than that of the oil; that the yearly mean is greater than 50 Fah., and that nothing was said of the increased hight of the tank. All, of course, for the reason of their insignificance, and because the the expansion of the iron was taken as not interfering with the figures of the tank. " The above results agree with the writer's experience of oil stored in this vicinity." Tidioute, Pa. Rights of Inventors. MESSRS. EDITORS :—I so fully believe in the rights of inventors, that I am sorry to see them hazarded by any attempt to urge them to an extreme and ridiculous extent. I therefore have little sympathy with the criticisms of your correspondent, G. W. P., who objects not merely to Mr. Greeley's argument in defense of the idea of protection for a term of years, as distinct from perpetual protection, but to the idea itself, as embodied in our Patent Laws. It seems to me that Mr. Greeley and G. W. P. have both made a serious mistake in regarding an invention as ordinary property. The particular machine one may build is ordinary property, and may be so held. But the principle of its construction is not a piece of property. An invention is not a creation,—it is a discovery. When one invents lie simply takes a principle which is as old as the laws of nature. The laws which apply to property do not forbid one to imitate another in his transactions. They only prevent him from taking the material thing which the other has secured, whether it be land, or a gold nugget, or a machine. But the Patent system has its foundation in the idea that a man may not only hold a machine which he may build, but that he may also forbid any one to imitate that machine. The Australian miner, referred to by G. W. P., had a right to the gold nugget, just as an inventor has a right to his particular machine. But no law forbids another to imitate his example and " strike his pick a few inches into the earth," in the hope of finding, and holding for his own; another $50,000 nugget. The proper defense o f the Patent system is found only when one views it as a system of rewards.offered by the community, for the unfolding of natural principles to meet the community's needs. If one does not like the rewards offered, he need not do the work. If the community does not want the work, it need not offer the reward. But every community does greatly need this service, and so cannot afford to neglect to offer the reward. But talk about " innate and perpetual right" is entirely out of place. The Patent system is for the good of the whole community, and is not legislation in behalf of a particular class. Let every wise man defend it upon the ground of what is for the good of the community. Let attention be called to the fact that a people cannot prosper except as it shall employ some persons to unfold and wisely apply the as yet hidden laws of nature. Let there be the most resolute opposition to any suggestion to abolish the Patent Laws, in view of the fact that the community cannot afford to dispense with that service which the Patent Laws invite by offering to that service suitable rewards. If the rewards now offered are not sufficient, let that be shown, and a people, having even the beginnings of wisdom, will anxiously seek the increase of these rewards. But why should one talk about " innate and perpetual right," unless it be with the idea of bringing the whole system into contempt? J. D. B. Clinton, Mass. Nocturnal Hail storms. MESSR?. EDITORS :—In response to your request in issue of July 10, concerning " the occurrence of hail storms between sunset and sunrise," I will state that probably the greatest hail storm that ever transpired in this section of country, occurred here two years ago this summer. An intensely hot day was succeeded by a beautiful evening, pleasantly tempered with gentle southerly breezes. At half past eight, a large black cloud moved heavily toward the zenith from the west; its interior blazing continuously with red lightning, while the increasing reverberations of heavy thunder, appar-eutly shook the earth to its very center. Domestic animals were unmanageable, and the human mind was fraught with awe and apprehension. Occasionally, gusts of chilling air swept from the northeast, bearing fragments of fleecy vapor, which manifested electrical excitement upon nearing the great cloud. After a few seconds of ominous silence, the storm burst forth. An avalanche of hail of immense size, driven by a furious gale from the west, denuded trees of twigs and foliage, and did immense damage to property; in many instances killing fowls and small animals, and leaving scarcely a pane of glass in windows exposed to its fury. The Erie Railway company alone lost several thousand panes from the skylights of their machine shops. At the conclusion of the storm, which lasted fifteen minutes, I picked up hail of an oblate spheroidal form, measuring two inches in diameter and three fourths of an inch axially. The storm limited its fury to a district four miles in length by one mile in width. P. Susquehanna Depot, Pa. Mr. J. J. Weber, of St. Clair, Schuylkill Co., Pa., writes that a hail storm occurred at that place, May 13, about 10 o'clock, P.M. " The windows of houses, on the northwest side, were, in some instances, broken, though the hailstones were small. They came down very thick and with tremendous velocity. " We had another hail storm here about seven or eight weeks ago. On this occasion the hail stones came thicker and faster than on the previous one, the ground being yet covered with them in some places, half an hour after the storm had subsided. " I have noticed that hailstones never fall when the clouds are low; that whenever they fall you cannot see a distinct outline of a cloud, all being dark overhead, showing that hailstones come from an immense hight, through the cold current of air running from the north pole to the equator. I have often noticed three or four currents of air running one under the other in opposite directions, and my belief is that whenever the vapor is carried up to, or beyond the cuirent of air coming from the pole, hailstones are formed; if not carried so high, it descends again in the form of rain." How to Make Good Bread. MESSRS. EDITORS :—Liebig justly complains of the stationary character of bread-making; but in recommending the use of chemicals only, that by the generation of carbonic acid gas in the oven render the dough spongy, he loses sight of the general demand for good fermented bread, and that the fermentation should be accelerated, improved, and rendered reliable to insure a good product. The desired pleasant taste and flavor of good bread are due to vinous fermentation, in which sugar and alcohol are formed from starch, and carbonic acid gas directly evolved, which, in this manner, remains more intimately combined with the dough. While the soft dough is constantly stirred, air should be introduced from below to accelerate and insure the process of fermentation, which only requires about two h'urs, or less if the ferment was sufficiently vigorous, to be ready for molding, and shortly after for the oven. This has been practically demonstrated. The phosphoric acid, to increase the nourishing property, could be added while the fermentation proceeds, and thus the advantages claimed by Prof. Horsford's baking powder, combined with those by thorough fermentation, are economically and safely obtained. The fermentation by air-treatment is patented, but the patentee gives it free for family use. reserving to himself the right to the manufacture of articles when engaged in by bakers and manufacturers of fermented beverages, etc. He will cheerfully give further information to parties interested. The Same process holds good for purifying drinking water, by 87 injecting air into private cisterns, wells, or other receptacles. E. D'HEUEEUSE. P. 0. Box 6,844, New York city. Anthracite Ashes for Earth Closets. MESSRS. EDITORS :—In the SCIENTIFIC AMERICAN for July 17, page 36, your article on " Moule's Patent," speaks of the ashes of anthracite coal as a deodorizer. The suggestion is of great importance; for even in the country, one cannot always get earth without disfiguring his ground, or sending, with expense, to a distance. And it is quite convenient to find.a new place for the disposition of coal ashes. But an important question has occurred to me—the value of composition of night soil with ashes of anthracite coal as a fertilizer. I have looked in vain, through some cyclopaedias, to discover the element* of these ashes. If Mr. Waring, or if the company whose advertisement you publish, could give a favorable answer to the question of the value of the mixture, the introduction of the earth closets might be much facilitated, and the health and lives of the community, as well as the household convenience, be very greatly acknowledged. May my question be answered ? E. BUCKINGHAM. Deerfield, Mass. [The fertilizing value of night soil, mixed with anthracite coal ashes, compared to that mixed with dry earth, in both cases the proper proportions being observed, we estimate roughly at about as three to four, taking the average character of soils into consideration. On stiff clay soils it would be better than this, and in any case it would be a valuable compost.—EDS. What Chemistry Tells us of Life. The following closing remarks of the Faraday lecture, delivered by M. J. Dumas, June 17th, before the Chemical Society of London, are worthy the attention of those who are striving after ultimate causes. Their eloquence and force are especially striking, while the sound philosophy they embody teaches the inutility of vain speculation upon matters that must ever be taken on faith. " If the discoveries which we have witnessed during the last half century do not justify pride, they at least excuse it. But, to bring back man to our appreciation of truth, it suffices to tell him that—if he has become more expert in the art of observing, if he employs with more certainty the art of experimenting, if the logic proper to the sciences leads him more surely to the discovery of the laws of nature—he has not as yet advanced one step towards the knowledge of causes. " Let us consider, in particular, what he knows on the subject of the materials which his life sets in motion in its development, and the contrast will be striking. " If I question the physiologist, on the subject of these millions, or milliards, of compounds, misnamed organic, of which the chemist transforms, reproduces, or creates at pleasure the species, he will reply to the three following questions :—Are these compounds living ?—No ! Have they lived ?—No ! Are they capable of living ?—No ! " If I ask the chemist himself if these compounds belong to mineral chemistry—to the chemistry of raw (brut) substances—he will reply, Yes! " Organized matter, not capable of being crystallized, but destructible by heat, the only matter which lives, or has ever lived—this matter, a subordinate agent of the vegetating power in plants, of the motion and sensation of animals, cannot be produced by chemistry; heat does not give birth to it; light continues to engender it under the influence of living bodies. " Let us not be disturbed by a quibble. The ancients admitted that nature alone produces organic matter, and that the art of the chemist is limited to transforming it. To-day we might, perhaps, even pretend that chemistry is powerful enough to replace, in all respects, the forces of life, and to imitate its processes; let us keep to the truth. " The ancients were mistaken when they confounded, under the name of organic matter, sugar and alcohol, which have never lived with the living tissue of plants or the flesh of animals. Sugar and alcohol have no more share of life than bone-earth, or salts contained in the various liquids. These remnants, or rubbish of life, placed amidst organic matter, are true mineral species, which must be brought back to, and retained among, ' brut' bodies. Chemistry may produce them in the same sense that she manufactures sulphuric acid or soda, without, for all that, having penetrated into the sanctuary of life. " This subject remains what it was—inaccessible, closed. Life is still the continuation of life; its origin is hidden from us as well as its end. We have never witnessed the beginning of life : we have never seen how it terminates. "The existing chemistry is, therefore, all powerful in the circle of mineral nature, even when its processes are carried on in the heart of the tissues of plants or of animals, and at their expense; and she has advanced no further than the chemistry of the ancients, in the knowledge of life and in the exact study of living matter; like them, she is ignorant of their mode of generation. " Where, then, is true organized matter, or matter susceptible of organization ? What is its chemical constitution ? What is its mode of production ? What is its manner of growth ? " Instead of myriads of species, one would feel disposed to recognize but eight or ten at most, if one may be allowed to consider elementary types of organization as chemical species. Be this as it may, in the origin of beings which have life we see cells appear, and in the heart of their types we find cells or organic elements, and, still beyond these, germs of cells* " In these cells, or in the spaces between them, we observe inert products, aliments, excretion, substances stored up. It is the cell, it is the germ3 which proceed from life, which live, which engender life, and then die. The substances which are contained in, or which surround these organs, are subordinate accidents, products rejected by organization, or destined to its use, but distinct from life. " Every organized being is born of a germ; every plant from a seed; every animal from an egg. The physiologist has never seen the birth of a cell, excepting by the intervention, or as the produce, of a mother cell. "The chemist has never manufactured anything which, near or distant, was susceptible even of the appearance of life. Everything he has made in his laboratory belongs to ' brut' matter; as soon as he approaches life and organization, he is disarmed. " Thus for a century past, the empirical elements of matter have been recognized and separated; their combinations have been multipliei to infinity; physical forces have been brought back to a common origin—motion—and one has been at pleasure changed into the other; and yet— " Is the intimate nature of matter known to us —No ! Do we know the nature of the force which regulates the movement of the heavenly bodies and that of atoms —No ! Do we know the nature of the principle of life —No ! " Of what use, then, is science ? What is the difference between the philosopher and the ignorant man ? " In such questions the ignorant would fain believe they know everything; the philosopher is aware he knows nothing. The ignorant do not hesitate to deny everything; the philosopher has the right and the courage to believe everything. He can point with his finger to the abyss which separates him from these great mysteries—universal attraction which controls ' brut' matter, life which is the source of organization and of thought. He is conscious that knowledge of this kind is yet remote from him, that it advances far beyond him and above him. " No : life neither begins nor ends on the earth; and if we were not convinced that Faraday does not rest wholly under a cold stone, if we did not believe that his intelligence is present here among us and sympathizes with us, and that his pure spirit contemplates us, we should not have assembled on this spot, you to honor his memory, I to pay him once more a sincere tribute of affection, of admiration, and respect ! " An Imported Steam Plow. A steam plow and accompanying apparatus, imported by Colonel Wm. E. Patterson from Leeds, England, was lately put in operation on the recent purchase of that gentleman in New Jersey. Colonel Patterson's large tract of land is to be devoted to the culture of sugar beet. As the soil is a sandy loam, closely akin to that in which the French have been so successful in sugar beet culture, Colonel Patterson sees no reason why a profit cannot be realized in this country in the same direction. The test of this steam plow was made in the presence of a considerable number of people, including General Capron, of the United States Agricultural Bureau at Washington. This gentleman, having beaten his sword into a plowshare, has, from the first, taken active interest in the subject of relieving horses from this arduous and exhausting labor. Through his intervention, the apparatus, which cost $13,000, was admitted free of duty, and, at its successful operation on TueB-day, no one evinced a higher degree of satisfaction. The machinery is by no means complicated. At opposite sides of the space to be plowed are two steam engines upon wheels. On the trial on Tuesday they stood three hundred yards apart. The plow has six shares. It is a distinct piece of mechanism, and is fastened to a steel wire cable extending between the two locomotives across the ground to be turned over. It is literally a shuttle cock between two steam battledores. It moves at the speed of a hundred yards a minute, turning six furrows a foot each in width, and eight inches in depth. Its average work, therefore, is twenty acres per day. The locomotives are snug machines, capable of being applied to many useful purposes independent of duty as steam plow-ers. A man rides on the plow as it crosses the soil. General Capron essayed a trip or two, guiding the machine like an expert upon a velocipede. One of the experts who mounted it just after him, had less good fortune. One of the diggers struck a buried boulder. When an irresistible body in motion strikes against an immovable one, a rumpus must be the result. In this case the man upon the machine wag slung high into the air. The concussion broke off two of the teeth of the digger, but as a new one immediately replaced it, the accident was a matter of little consequence. Of this large track of ground much is virgin soil. The trunks of many cedars, showing slight evidences of decay, were brought to light by the steam plowshares. These were crunched up by them as if they were mere touchwood. The soil above them is largely made up of decayed vegetable mat ter, and, in the opinion of all who were present, the sugar beet will produce in it enormous crops. A digging machine accompanies the plow, intended for use in soils where roots and stones are obstacles to the course of the plowshare. This is a wonderful apparatus. It so triturates the stiffest soil that a Yankee might put it into bladders and vend it as a substitute for snuff. To work the machinery costs extremely little. Anything anwers as fuel, and, at the rate of twenty acres a day, a large estate is soon put under cultivation. Th; locomotives are then ready for ordinary duty as steam i.ngines, either to grind or thrash, Bew or mashi—Journal of Franklin Institute. Glycerin and Distillation. We think, says the Druggist's Price Current, the time has come when the use of any glycerin having the least impurity, should be abandoned, as the price of the pure article is so low that there is but a slight difference between it and that of impure. For medical purposes, for extracts, as a substitute for sugar in medicinal sirups, pure glycerin only should be used, and will specially be valuable in warm weather, as glycerin does not ferment, and the sirups will hence keep much better than sugar would. The perfumer will find it to his advantage to use a pure glycerin, as it requires less perfume. We would particularly warn against the use of an impure article for hair-oils or hair-tonics, as the lime or lime salts cause an irritation of the scalp and the consequent falling out of the hair. Glycerin having any odor is not fit to be usei for these purposes, even if the odor be covered by perfume, as the perfume will volatilize first and leave the rancid smell. For the benefit of those not versed in chemistry, we give a few simple and practical tests, to detect impurities in glycerin : 1. Specific gravity. Employ Baume's hydrometer. Glycerin, weighed at the temperature of 60 Fahrenheit, should have no less than 29 B.; if it contains lime or alkalies, one degree should be deducted, as these substances make it heavier. 2. Odor. Rubbed on the hand, it should be perfectly inodorous. Impure glycerin, under this test, has a disagreeable smell. The impurity causing this odor is mostly butyric acid, as by contact with the glycerin, it forms a very volatile glycerole. Such an article will always grow worse by age. 3. Lime, or salts of lime. Take a solution of oxalic acid, add some spirits of ammonia, and mix this with a small portion of glycerin; if the mixture remains limpid, the glycerin is free from lime; if a white precipitate forms, then lime is present. 4. Chlorine, or chlorates. Add a few drops of solution of nitrate of silver to the glycerin; if a white percipitate forms, the above impurities are present. 5. Sugar, grape or cane, is an adulteration which is sometimes found in foreign glycerin. Cane-sugar can be detected by the taste, as glycerin is not as sweet as sugar; but grape-sugar can be discovered by the polarization of light, which requires a costly apparatus, or by caustic potash, which requires an expert. Hence, when glycerin is expected to contain sugar, it should be given to an experienced chemist. One of the most recent improvements in the distillation of glycerin is the process patented through the Scientific American Agency, by O. Laist, of Cincinnati, Ohio, and heretofore noticed in our columns. The glycerin is heated in the still by means of fire, to the point required; but, as glycerin is liable to decompose on being heated in a vessel filled with air, a small j et of steam is introduced into the still to expel the air, and, as the steam condenses in the condenser, a vacuum is thus created. The condenser is so arranged that the gylcer-in condenses while the water and volatile impurities evaporate; a draft being created to prevent their condensation. As the glycerin is liquid at over 300 Fahrenheit, no loss by evaporation need be feared. Of course all mineral (not volatile) impurities remaining in the still, while all volatile impurities evaporate, the glycerin must come out entirely pure, and must be of the highest specific gravity, as no water can condense. Glycerin made by this process was found to be inodorous, colorless, and of a specific gravity of 1'253, being more than the United States Dispensatory requires, besides being free from all mineral impurities. New Dose for Hogs. A singular discovery, says the Druggist's Circular, has just been made at Cincinnati. It seems that a man upset his kerosene lantern into his meal bin, and he noticed afterwards that his hogs ate the damaged fodder with avidity. This gave him an idea, and by experiment he found that five weeks' feeding with the kerosene mixture made one of his hogs so fat that it could scarcely stand. The animal was then fried into lard with the following result: When cool, the lard did not congeal, but the addition of a certain amount of potash resolved the contents of the kettle into three distinct substances—the first, a light, transparent oil, better than kerosene or sperm oil; the second, a jelly-like substance, which turned to soap; and last, a small residuum of insoluble muscle. The quality of the meat as food not being mentioned, we may infer that kerosene pork is not considered a delicacy. NEW TEST FOR BLOOD STAINS.—Upon the authority of the London Lancet, an important test for blood had been discovered in Australia; consisting of the application of tincture of guaiacum and ozonized ether, which produces a beautiful blue tint with blood or blood stains. The test is excessively delicate; and we happened to be present at a lecture given by Mr. Bloxam, in which he showed some experiments with it, and added that, in the case of a blood stain twenty years old, he had extracted a single linen fiber with an almost inappreciable amount of stain on it. The characteristic blue color was immediately induced by the test, and readily detected by microscopical examination. The testimony of so able a chemist leaves no doubt as to the value of the discov ery. Ozonized ether, we may remark, is merely a solution of peroxide of hydrogen in ether. M. ARAGO was the first to observe that a wire, when traversed by a powerful current, and plunged into iron filings, retained around it considerable quantity—a mass of the thickness of a quill. # 88 Device for Tightening Tires of Wagon Wheels. The purpose of this invention is to produce means whereby tires maybe set cold, properly tightened, and held without the usual rivets or bolts. Kg. 1 is the representation of a portion of a wheel with this device attached. The two ends of the tire to be joined are provided with two right angular pieces of metal, A, welded to the tire, as shown in the engraving. A screw bolt passes from one of these angular pieces, or blocks, through the other, and is drawn up to any required extent by turning the nut, B, upon it This tightens or sets the tire. When the tire is sufficiently tightened a metallic box, C, Figs. 1 and 2, is placed over the pieces, A, and the other attachments described, and is held to place by the nuts and bolts, D, Figs. 1 and 2. This box is intended to strengthen the rim of tle wheel enough to compensate for the cutting away of the rim, and to protect the inclosed parts from injury and exclude dirt. The inventor claims for this invention simplicity, strength, and economy. Heating is avoided by it's use in the setting of tires, and the required degree of tension can be attained with accuracy. Patented through the Scientific American Agency, January 5,1869, by Harris and Hai-vey Pearson, of Depeyster, N. Y. A part, or the whole of the right for the United States will be sold. For further particulars address as above. To Measure Hights. A very compact and useful instrument, called the "Apome-cometer," that can be carried in the waistcoat pocket, for ascertaining the vertical hights of towers, spires, and other buildings, has been invented in England. It cannot be better explained than by quoting the description given by Mr. Millar, the inventor : " The 'Apomecometer' is constructed in accordance with the principles which govern the sextant, viz., as the angles of incidence and reflection are always equal, the rays of an object being thrown on the plane of one mirror are from that reflected to the plane of another mirror, thereby making both extremes of the vertical hight coincide exactly at the same point on the. horizon glass; so that, by measuring the base line we obtain a result equal to the altitude." The Emperor Napoleon III. as a Man of Science. The Emperor Napoleon III., sayB a contributor to the London Scientific Review, has frequently been before the public in the capacity not only of an ardent promoter of scientific research, but also as an original investigator in some of the most interesting branches of physical science. His little work on The Gannon met with considerable success, and at the time at which it appeared was calculated to throw much light upon this dreadful engine of war. But his physical and mechanical investigations have been moBt often directed to the development of the peaceful arts. At the time that FrangoiB Arago was secretary of the Academy of Science in Paris, the Emperor (then Prince LouiB Napoleon) presented a very interesting paper on the disturbances of the magnetic needle—the reBult of some investigations carried on at Ham, in which it waB remarked that the iron bars at the windowB interfered very much with the oscillations of the needle. This paper found its place in the Gomptes Bend-us of the Academy, where it may be consulted with interest by those who follow up the gradual development of magnetic science. Some years ago the emperor was aBtonished at the great space occupied by flour when packed in Backs in the usual manner, and imagined that it might be compressed into a much smaller bulk, and be thus rendered of much easier transport. He at once authorized some experiments to be made on the subject, which resulted in the flour being submitted to powerful hydraulic pressure, and served to the various regiments in tin cases, not only occupying a very small bulk, but protecting the flour from the damp of the atmosphere, and so preventing it from becoming moldy. But, besides his own practical researches, Into the details of which we cannot enter here, the Emperor of the French has distinguished himself most conspicuously as a promoter of scientific research in France, and has thus set an admirable example to the other crowned heads of Europe, eome of whom appear already to see the advantages of following it. Within the last few years, as we have occasionally noticed in this journal, chemical, agricultural, astronomical, and physical researches have been carried on by various eminent men at the Bmperor'B private cost, and have had very considerable influence upon the progress of science in Europe, It was, then, with much pleasure that we witnessed the departure last week, for Paris, of Mr. ChaB. Hutton Gregory, President of the Institution of Civil Engineers, accompanied by several distinguished members, to present to the Emperor Napoleon III. the diploma of honorary member of their institution. The deputation was received most graciously by His Majesty, who requested that his sincere thanks might be conveyed to the members for the honor conferred upon him. The cordiality which marked the official reception, and the special and even friendly hospitality which followed it, showed that the Emperor warmly appreciated the compliment which had been paid to his scientific attainments and to his enlightened encouragemot of scientific- pursuits and public works. The family of the Bonapartes has numbered many very distinguished men of science. Napoleon L, when at St. Helena, remarked that if he had to begin his life again he would follow a scientific career; Prince Lucien Bonaparte has made himself a reputation in science by his chemical researches. Prince Charles Bonaparte was one of the most renowned ornithologists of this century, and the present Prince Napoleon has already distinguished himself by his voyages and travels, undertaken for the purpose of promoting scientific knowledge.
This article was originally published with the title "Correspondence"