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Popular Science Monthly/Volume 49/May 1896/Fragments of Science

< Popular Science Monthly‎ | Volume 49‎ | May 1896

Fragments of Science.

Commerce and Drought.—The serious loss which a prolonged drought may cause, not simply to agriculture, but in an even more marked degree to commerce, is drawn attention to by Prof. L. M. Haupt, in a recent number of the Journal of the Franklin Institute. He says: "One of the most impressive lessons to be derived from the absence of sufficient water for commerce is to be found in the experience of the communities on the upper Ohio River during the past season of exceptional drought. The harbor of Pittsburg, which is made by the movable dam at Davis Island, and the fixed dams of the Monongahela slackwater system, forms a convenient basin in which to make up the tows of coal boats and barges which supply the Mississippi and its tributaries. It is the custom to assemble these tows above the dam and await the pleasure of Pluvius to provide a flood with sufficient depth of water to carry them out. During the past season there has been no coal shipped by river between the 18th of April and the 28th of November (over seven months), and the accumulation of the product had gone on until the tonnage tied up exceeded that of any harbor in the world. For miles on both banks of the river the steamers and their fleets lined the shores, and the danger of their being frozen in all winter was imminent, when a heavy rain released two hundred thousand tons; but a part of these met a watery grave on the shoals of Dead Man's Ripple, a short distance below Pittsburg. The extent of this congestion can not be appreciated by one who has not seen it, and it is far-reaching in its effects, as it directly concerns the industries of millions of people. The actual value of the plant tied up in the harbor of Pittsburg alone, as stated by Hon. John F. Dravo, Secretary of the Coal Exchange, on November 7, 1895, was $6,500,000. At the present time it is costing about two thousand dollars per day to keep this tonnage afloat, besides interest on the investment. This 'tie-up' of Nature has seriously crippled the entire valley, as the railroads can not do more than maintain a partial supply, and the price of fuel has risen in some of the larger cities one dollar a ton." The author cites the above incidents as showing that a more liberal policy in spending public money for river and harbor improvements would, in the long run, be the most economical.

 

The Bamboo as a Food.—Young bamboo shoots are eaten by the Chinese and Japanese as we eat asparagus. Dr. Lamounier, who has a collection in his garden at Verneuil, France, tried two or three species at a right age, and found them excellent. The stalks should be taken very young during the first fortnight of spring growth, and should not be more than fifteen centimetres thick. The outer envelopes of spathes are taken off, and the soft substance is left, crisp and brittle, and yielding easily to the pressure of the finger. Dr. Lamounier says they have the general taste and flavor of Brussels sprouts, and that they are wholesome, easily digestible, and economical. But all depends on the time of cutting and the preparation. Some canned bamboo, exhibited by the Japanese at Paris in 1889, was found hard and flavorless. We have these differences, too, in asparagus and all vegetables, while we judge the quality of the same from their best, not from their worst.

 

Tuberculosis and Meat Inspection.—In a paper presented to the New York Academy of Medicine during last November, Prof. Leonard Pearson, of the University of Pennsylvania, gave a résumé of the recent work of foreign veterinarians on bovine tuberculosis. We take the following points from a reprint of the address in the Dietetic and Hygenic Gazette. "This subject," he says, "has been a live one in Europe for many years, and has received much attention ever since it was shown by Villimen, in 1868, that the disease could be transmitted from one animal to another, and more especially since the discovery of the tubercle bacillus by Koch in 1882 and the consequent establishment of the fact that the tuberculosis of men and the lower animals is the same disease and caused by the same germ. Most of the European countries now have a system of meat inspection, which is carried out most carefully in the great centers of population, and usually assures the consumer against harmful flesh. The question as to what shall be done with tuberculous carcasses has excited much discussion. There is practically unanimity regarding the immediate and entire destruction of the carcasses of animals that show generalized tuberculosis, or tuberculosis with marked emaciation, but the cases of localized tuberculosis are much more common, amounting Ln some places to fifteen or eighteen per cent of all cattle slaughtered. The careful experiments, however, of Chauveau, Nocard, Bollinger, Bang, and McFadyan have shown that the flesh of animals with local tuberculosis is not infectious. It has been shown, however, that if there are any tuberculous spots the butcher is likely to get infected material from this spot on his knife and spread it more or less generally over the carcass. At the International Veterinary Congress held last September in Berne, it was decided by resolution that the flesh of tuberculous animals should be condemned when the carcass is emaciated, when it has a general bad appearance, when tubercles are found in the muscular portions, and when alterations are found in several organs. It was also recommended, in relation to the flesh of slightly tuberculous animals, that it be permitted to go on the market, but that it be sold in special shops or stalls, or sterilized and sold as cooked meat. In Germany the practice is to condemn the worst cases, sterilize those that are less extensive, and to pass as sound the slightly developed cases, after destroying the affected parts. A very important point in connection with this subject is in reference to the payment of indemnity to the owner of the condemned animal or carcass. It is felt that, as the animal is condemned for the good of the public, they should bear part of the loss. Already in France it is the custom to compensate the owners of infected animals which are destroyed. The consideration of the milk from tuberculous cows is also of great importance. Numerous investigations have demonstrated that the milk of cows with tuberculosis of the udder will cause tuberculosis in a very large percentage of the animals fed upon it. Ostertag recommends that the milk from cows with tuberculosis of the udder should be excluded from consumption, and that from cows which react to tuberculin, but show no evidence of tuberculosis of the udder, should be sterilized before sale. In a recent report from the Royal Commission on Tuberculosis in Animals the statement is made that 'the withdrawal from dairies of every cow that has any disease whatever of the udder would form some approach to security against the serious danger incurred by man from the use of tuberculous milk, but it would not be an adequate security.' The presence in a dairy of a tuberculous cow, the report says, is a decided source of danger to the public, especially having regard to what has been learned respecting the rapid development of tuberculosis of the udder. Regarding the value of tuberculin injections as a diagnostic agent, the following resolutions were adopted at the International Veterinary Congress held last September, and hence represent the opinions of the foremost veterinarians of Europe: 'No. 1. Tuberculin is a very valuable diagnostic agent and can yield the greatest assistance in combating tuberculosis. There is no reason for objecting to its general application on the ground that it may aggravate pre-existing tuberculous lesions. No. 2. The congress expresses the desire that governments shall order the employment of tuberculin in herds in which the existence of tuberculosis has been established.' The official veterinarians of Germany are advised to use tuberculin, and are supplied with it at a low cost from the government laboratories."

 

Tibetan Women.—As described by Mr. W. W. Rockhill, the Tibetan women are usually stouter than the men, with fuller faces, and do not entirely lose their good looks before they are thirty or thirty-five years old. They are as strong as or perhaps even stronger than the men, because, being obliged to do hard work from childhood, their muscles are more fully developed than those of the men, who do not carry water on their backs, work at the loom, or tend the cattle. Their hair is long and coarse, but not very thick; it remains black, or only mixed with a little white, to extreme old age; and both men and women with white hair are rarely seen. The skin of the Tibetan is coarse and greasy, light brown in color, frequently nearly white, except when exposed to the weather, when it becomes a dark brown, nearly the color of our American Indians. Rosy cheeks are common among the younger women. The Tibetans' voices are powerful, those of the men deep, those of the women full and not very shrill. Their hearing is good, and they can converse freely from one side of a valley to the other, a distance of half a mile, without ever having to repeat phrases or perceptibly raise the voice. They can endure exposure without any apparent inconvenience, the women doing their work with the right side of the body completely exposed, and small children going naked, or with only a pair of boots on, except in the coldest weather. They can also endure hunger, and are at all times small eaters.

 

A New Glass Construction.—We take the following from a report presented by Dr. Schott to the French Society for the Encouragement of National Industry: For siliceous glasses the expansion increases with the proportion of alkali. Boric acid produces a striking decrease of expansion. In superposing upon each other two glasses of different compositions, it is requisite that there should exist a certain relation between the relative thickness of the two layers of glass and their coefficients of expansion. Thus at Jena they solder normal thermometer glass, the coefficient of cubic expansion of which between 0° and 100° = 0·0000244, to an aluminous sodium borosilicate, the expansion of which = 0·0000177. The former kind of glass must be placed externally and the second internally in order to form a hollow vessel or tube. We may also join together three or more layers of two or more glasses. Of two layers of glass with different expansions after cooling, that with the greatest expansion will be in a state of tension and the other in a state of compression. External layers in a state of compression increase in a striking manner the resistance of glass to mechanical actions and to rapid changes of temperature. Flasks thus manufactured may be strongly heated (to a temperature of 184°), and may then be sprinkled with cold water without injury. Such glasses are not liable to the sudden rupture which is apt to occur in glass tempered by the process of De la Bastie.

 

An African Village Scene.—"I doubt," says Dr. D. Kerr-Cross, "if finer villages or better built houses exist anywhere in uncivilized Africa than are found among the 'Wa-nyakyusa' people" of the district north of Lake Nyassa. Round houses are occupied by the married people, but they also build square houses and long cattle-folds. The walls are of bamboo set into the ground at an angle of about 100°. Small bricks about the size of an ostrich egg are fitted neatly, while plastic, into the framework. The whole is a huge basket of bamboo reeds and mud. The reeds on the roof are tied in wavy lines in the form of a dome, the thatch is laid with great skill, and the house is scrupulously clean. Large villages are uncommon, but on the plains one village is connected with another by banana groves which often extend for miles. Trees are planted for utility and for ornamentation, and are regarded with pride. There are no stockaded villages, but a kind of poisonous cactus is grown as a defense. All manual work in cultivation is done with giant hoes. Their fields look as if they had been deeply plowed, and every furrow is perfectly straight. They are a tall, muscular race, of few wants, desiring nothing of strangers. They appreciate cloth, but have little idea of its value. They are in what one might call the "brass-wire age." That is their medium of exchange, and anything can be bought for it. Iron is found in the King's Mountains, and is extensively wrought. They make iron, copper, and brass belts as thick as one's little finger, and wear them on the waist. Six or more of such belts may be worn on the person of one individual. Their word for riches means iron. The Nkonde spears are famed. Though not so large as those of the Masai, their spears and billhooks are cruel-looking weapons, with long barbs. The shafts are made of a dark, hard wood, and are frequently dyed black. They are ornamented, and often beautifully inlaid with a delicate tracery of brass, copper, or iron. They have fifteen varieties of spears, bearing different names.

 

The Storing of Acetylene.—In a recent letter to the Engineering News, Frederick H. Lewis gives the result of some instructive calculations. It has been claimed, it seems, by several concerns that acetylene gas may be liquefied and stored in metal "bottles," and in this form advantageously handled and transported. "The writer," says Mr. Lewis, "had occasion some time since to ascertain whether a small cylinder of about one half cubic foot capacity could possibly contain the amount of gas that the company's orator in Philadelphia had declared it to hold. A little calculation showed that if the gas was present, as stated, its density must be nearly equal to that of cast iron." Mr. Lewis calculates that a cylinder containing sufficient gas to supply a private house for a month would have to be about eight feet and a half long, and would weigh three hundred pounds. "But," he says, "even this statement of the case is entirely too favorable. The fact which the acetylene-gas people must face is this, that it is entirely unsafe to liquefy gas whose critical point is only 98° F., and subject such cylinders to the incidents of transportation and of ordinary use in dwelling houses. It has been found necessary to adopt this view in the case of nitrous oxide for dentists' use, and it will be necessary with acetylene."

 

Gout and Genius.—From an interesting little essay in the Lancet, by Mr. J. F. Thiselton Dyer, on the folklore of gout, we take the following: Many years ago one Misausus wrote a curious little book in honor of the gout, with the object of proving that it was a blessing for which mankind could not be too thankful, arguing that if Paracelsus could make men proof against death his secret consisted in inoculating them with gout. But when it was suggested that gouty people do die, he replied that men know not when they are well off, but must needs be curing the gout, and therefore deal with death's factor, the physician. It was, however, a popular notion that gout lengthened life, and statistics at the present day show that it is not answerable for more than one death in every seventeen hundred and eighty. For a long time gout had the reputation of being preeminently the rich man's disease, and Sydenham, who, it may be remembered, was the first man minutely to study the disease, remarked that, unlike any other complaint, "it kills more rich than poor; more wise than simple. Great kings, emperors, generals, admirals, and philosophers have died of gout." In one of Pitt's last letters to the Marquess Wellesley, he alludes to his slow recovery from severe attacks of gout, and both the Earl of Chatham and Fox were afflicted by it. Horace Walpole was another victim, and, after comically describing himself as wrapped in flannels, like the picture of a Morocco ambassador, he says: "If either my father or mother had had it, I should not dislike it so much. I am herald enough to approve it if descended genealogically, but it is an absolute upstart in me, and, what is more provoking, I had trusted to my great abstinence for keeping me from it; but thus it is." Sydney Smith, when writing to the Countess of Carlisle in his seventy-first year, speaks of his gout, and humorously says: "What a very singular disease it is! It seems as if the stomach fell down into the feet. The smallest deviation from right diet is immediately punished by limping and lameness, and the innocent ankle and blameless instep are tortured for the vices of the nobler organs." The fact that gout occurs among the poor and temperate Faröe islanders, and that it may be generated by a low diet and abstinence carried to extremes, would seem to indicate that it is not always caused by overfeeding. Among some of the literary men and poets who have suffered from gout may be mentioned Fielding, Newton, Linnæus, Milton, Congreve, and Dryden, and of warriors included among its victims Lord Howe, Marshal Saxe, Wallenstein, and Condé. Dr. Cullen was strongly of opinion that all gout must be considered hereditary. Modern science has somewhat qualified this assertion, maintaining that three out of every five cases may be regarded as inherited. It is worthy of note that where there is a predisposition for gout a fit may be induced by the most opposite causes; and whereas Kingsley's "northeast wind" will excite it in some instances, a mathematical problem has been known to produce it in another. It seems incredible that any one should desire gout, and yet it is said that Archbishop Sheldon not only wished for it, but actually offered as much as five thousand dollars to any person who would keep him to it; for he looked upon gout as "the only remedy for the distress in his head." Gout is not confined to any one class, and has afflicted some of the ablest men in all ages, although, strange to say, it is five times more frequent in men than in women.

 

The Unapproachable Antarctic Continent.—Whether it will ever be possible to make a satisfactory exploration of the antarctic continent is a matter of doubt, on which very little if any light is shed by the reports of Mr. Borchgrevink, the latest navigator who has tried to penetrate the region. The defenses of the shores against approach are considerably more formidable than those of the arctic seas, and consist of the "pack," a moving mass of icebergs of enormous size, and floating ice; within this, a rim of compact ice, fringing the greater part of the shore, and extending out often several hundred miles from the land; and the ice barrier of the land itself. Captain Cook did not believe that any man would venture farther toward the pole than he had gone; but in 1823 a Captain Weddell found an unusually extended break in the ice fringe, and reached 74° 15' S., but not the mainland. Yet he found the antarctic islands almost inaccessible, constantly covered with snow, except some perpendicular rocks, and nearly destitute of vegetation. Sir James Ross sailed in sight of the antarctic mountains, a hundred miles away, but was not able to make a landing. Wilkes saw land at several points, but could not pierce the ice barrier. Even if a landing were made, the country does not seem to afford even the poor facilities for exploration which the arctic regions furnish; it has few known animals and no inhabitants, of which arctic travelers are often able to make considerable use.

 

Metallic Iron In Water Purification.—Mr. F. A. Anderson recently delivered an interesting address before the Society of Arts on the purification of water by means of metallic iron. While this method is not a new one, and has been in use in various English towns for some years, Mr. Anderson's paper is worthy of attention as giving a very clear description of the apparatus and methods of the process. He says: "The idea of purifying water by agitating it with metallic iron is due to Sir Frederick Abel. The revolving purifier is a cylindrical vessel, supported horizontally upon hollow trunnions, through one of which the water to be purified enters; after traversing the cylinder it leaves by the other trunnion. The cylinder is caused to rotate about its axis by means of a gearing. A number of curved shelves running longitudinally are fixed inside of the cylinder. The iron may be in any convenient form, but the most commonly employed in practice is the burrs or punchings from plates. The charge varies, of course, with the size of the cylinder, a purifier capable of treating a million gallons of water in twenty-four hours requiring about two tons. When the machine is set in motion, the curved shelves scoop up the charge of iron and shower it down through the water, thus causing a constant falling of iron across the current of the water. The effect upon the water of the agitation with iron is simply to cause a email quantity of iron, from one tenth to one fifth of a grain per gallon, to be dissolved. The water emerges from the purifier and passes to settling tanks, where the ferrous hydrate, which has been formed, is oxidized into ferric hydrate, and settles to the bottom of the tank. From the settling arrangement the water passes on to the filters, which are sand beds of ordinary construction; through these filters the water passes at the rate of from eighty to one hundred gallons per square foot per twenty-four hours, and emerges pure and free from any trace of iron. It was formerly considered that the iron had a more or less pronounced chemical action upon the dissolved organic impurities of the water; the oxide formed was considered to act as a carrier of oxygen, by means of which the organic matters were actually burned up and destroyed. It is tolerably certain now, however, that the real action is one of coagulation; the formation of a precipitate in the water tending to throw out of solution the dissolved organic substances, which form with the ferric hydrate insoluble compounds, so to speak, which are removed from the water by settlement and filtration. This view of the action of the iron upon the organic impurities of a water applies equally well to its action upon microbes. The germs are entangled in the gelatinous precipitate, and either subside with it to the bottom of the settling tank, or remain behind on the surface of the filter. Moreover, the film of oxide which covers the surface of the sand appears to act like a Chamberland-Pasteur filter, retaining the microbes while allowing the water to pass freely. A very important feature of the iron process consists in the rapidity with which perfect results are secured. A sand filter of ordinary construction will remove a very large proportion of the microbes in a water when its surface has become sufficiently blocked by the layer of matter, living and dead, separated from the water being filtered. To obtain this result, however, it is necessary to work the filter for days, delivering all the while imperfectly filtered water, until this layer has time to form. With the iron process, however, no such thing occurs. The practice is, when a filter is restarted after cleaning, to refill it from below with purified water from another filter until the surface of the sand is submerged; and then to admit from above water direct from the outlet of the purifiers, containing in suspension the whole of the iron oxide supplied to it. This turbid water as it settles immediately forms the desired film. Then the filter is set to work, and yields, from the first, water containing the minimum number of germs. The film thus formed is quite clean, and is never slimy or offensive.

 

Recent Experiments in Flying.—In an interesting article in Nature describing and picturing the flying appliances of Herr Otto Lilienthal, who has been experimenting for some time past near Berlin, it is said that his experiments "have from the very beginning been rewarded with a distinct success; and it seems that, given time, he may present us if not with a method of flying, then with an approximation to it, which perhaps at some later date may be more fully developed." He has already succeeded in making fairly long flights with perfect safety. His present apparatus consists of two parallel planes one above the other, the upper being about three fourths of a wing breadth above the lower. Each plane has an area of nine square metres. The planes are slightly concave on the lower side, and each one is divided into two wings by a fore-and-aft hinge. There are two rudders at right angles to each other fastened to the rear end of the lower plane. With this new apparatus Herr Lilienthal has already found that a step in the right direction has been made. The energetic movement of the center of gravity, and the consequent more safe management of the apparatus, had led him to practice in winds blowing at times over ten metres per second. "These experiments," he says, "have given the most interesting results that I have arrived at since I began." With a wind velocity of six or seven metres per second, the sailing surface of eighteen square metres carried him against the wind in a nearly horizontal direction from the top of the hill without even having to run at the start, as is generally necessary. In a stronger wind he allows himself to be simply lifted by the wind from the hilltop and sail slowly against it. As experiments have shown, the sailing path is directed strongly upward by increasing wind force, and this fact causes him sometimes to be higher in the air than he was at his original starting point. In this position his apparatus has occasionally come to a standstill; and this leads him to make the following interesting statement: "At these times I feel very certain that if I leaned a little to one side, and so described a circle, and further partook of the motion of the lifting air around me, I should sustain my position. The wind itself tends to direct this motion. I have made up my mind by means of either a stronger wind or by flapping the wings to get higher up and farther away from the hill, so that, sailing round in circles, I can follow the strong uplifting currents and have sufficient air space under and about me to complete with safety a circle, and lastly to come up against the wind again to land."