Popular Science Monthly/Volume 47/September 1895/Popular Miscellany

From Wikisource
Jump to: navigation, search
Popular Science Monthly Volume 47 September 1895  (1895) 
Popular Miscellany
 

POPULAR MISCELLANY.

The Red Cross.—The organization known as the Red Cross is the result of the international treaty of Geneva, and has for its object the prevention or amelioration of suffering incurred in war. All military hospitals under its flag are neutral, and can not be attacked or captured. Surgeons, nurses, chaplains, attendants, and all non-combatants wearing its badge, all supplies, and whatever else, under its care, are likewise protected. In this country it has a civil branch, known as the "American Amendment," which other countries are adopting, and which provides relief against woes arising from fire, flood, pestilence, and other national calamities. As late as the Crimean War, civil help for military necessities was unknown, and Florence Nightingale walked into a pathless field. In our own civil war relief was afforded by the Sanitary and Christian Commissions. The Red Cross became active first in the Franco-German War of 1870-'71, and the annals of that war were not stained by any record of needless inhumanity or cruelty to wounded or sick. Since then no war between nations within the treaty has taken place in which the Red Cross has not done its work, maintained its position, and been respected. Under the "American Amendment" it has had a share, according to Miss Clara Barton, its originator and leading spirit, in relief work in the case of the forest fires of Michigan in 1881; the overflow of the Mississippi in 1882; the drought in Texas in 1886; the relief of the sufferers from the Mount Vernon cyclone in 1888; the yellow-fever epidemic in Florida in 1888; the Johnstown disaster in 1889; the Russian famine in 1891-92; and the hurricane and tidal wave of the South Carolina sea-island coast in 1893-'94. It has also, during that time, taken part in several international movements.


Unsolved Problems in the Manufacture of Light.—In a lecture before the Royal Society of Canada, on Unsolved Problems in the Manufacture of Light, Prof. John Cox showed that in practice not more than from seven to sixteen per cent of the energy stored in the coal can be extracted by the steam engine, and theoretical considerations fix an absolute limit to the perfection of that machine, so that we can never hope to convert so much as thirty per cent of the coal by any form of heat engine. This is one of the unsolved problems—unsolved, but still capable of solution if some means of extracting energy from coal otherwise than by heat, and more like the methods used in burning zinc in a battery, can be discovered. In the second stage of the process for producing the electric light, the dynamo is already nearly perfect, and hardly any heat is lost in its conversion into an electrical current. We reach the third stage, the lamp, with some seven per cent of the original energy still available. In this stage our only means of producing luminous energy is to heat the molecules of some substance, whereby we are compelled to waste the greater part of our efforts in producing heat, which is worse than useless, before we obtain the light rays. "Here, then, is the second unsolved problem, since even in the incandescent lamp and the arc lamp not more than from three to five per cent of the energy supplied is converted into light. Thus of the original store in the 710

��THE POPULAR SCIENCE MONTHLY.

��coal less than three parts in a thousand ulti- mately become useful. In the last six years, however, some hint of means to overcome the difficulty has been obtained from the proof by Maxwell and Hertz that light is only an electric radiation. Could we pro- duce electric oscillations of a sufficient ra- pidity, we might discard the molecules of matter and directly manufacture light with- out their intervention. To do this we must be able to produce oscillations at the rate of four hundred billions per second. Tesla has produced them in thousands and millions per second, and Crookes has shown how by means of high vacua to raise many bodies to bril- liant fluorescence at a small expense of en- ergy. . . . These are hints toward a solution of the problem, but give no solution as yet. Prof. Langley states that the Cuban firefly spends the whole of its energy upon the visual rays without wasting any upon heat, and is some four hundred times more effi- cient as a light producer than the electric arc, and even ten times more efficient than the sun in this respect. Thus, while at present we have no solution of these important prob- lems, we have reason to hope that in the not distant future one may be obtained, and the human inventor may not be put to shame by his humble insect rival."

Friends of the Farmer. The common white grub, the larva of the June bug, well known as a destroyer of potatoes and the roots of corn, is eaten by a considerable number of small animals. Among thosB mentioned in the eighteenth report of the State Entomologist of Illinois are thrushes, blackbirds, bluebirds, owls, hawks, the cat- bird, robin, and some other birds, also pigs, moles, ground squirrels, skunks, toads, and frogs. It is probable that snakes also eat them. Several of the above-named creatures are too destructive themselves to be encour- aged on farms, but others either do no dam- age at all or a trifling amount compared with the service they render. Poultry might have been added to the list given in the report.

Significance of Unman Variation. The

Shattuck Lecture, delivered by Prof. Thomas Dwight at a recent meeting of the Massa- chusetts Medical Society, was on the Range and Significance of Variation in the Human

��Skeleton. In it the author, who is convinced that every bodily difference between man and non-rational animals is of degree and not of kind, expresses himself " astonished and perplexed by the great network of anal- ogies extending throughout Nature. No one can ignore them without willfully shut- ting his eyes. But the very multiplicity of these resemblances assures me that some other law than that of heredity must be in- voked to account for them. They can not' be represented by a treelike figure. They spread out every way. The opinion is daily growing stronger among serious scholars that, if man's body came from a lower form, it was not by a long process of minute modi- fications, but by some sudden, or compar- atively sudden, transition. The fabulous missing link, once so accurately described by Haeckel, is retreating to the limbo of worn-out hypotheses."

Coloration of Birds' Eggs. The expla- nations put forth to account for the varia- tions in color of the shells of birds' eggs are arranged by Dr. R. W. Shufeldt in hia paper on that subject as follows : In many instances the general color and markings were in con- formity with the law of protective coloration. When both sexes are more or less brilliantly colored, the eggs are generally laid where they are not exposed to view, and where the parent hatching them is also concealed to a greater or less extent. This is effected by either the form of nest constructed or by the eggs being laid in burrows or hollow trees. The eggs of such birds are, as a rule, not handsomely marked, or are often only white. When the general tone of the plumage of the incubating parent is in har- mony with its environment, the eggs, as a rule, are laid in open nests or places where they are fully exposed to view ; such eggs are often very handsomely tinted and marked, or the reverse may be the case. Frequently birds that lay eggs in open and exposed places, as directly on the ground, rock, or sand, without any apology for a nest, have eggs that are either tinted, or colored and marked, or both, so as to be in harmony with their surroundings. The earliest forms of birds probably laid white, ellipsoidal eggs, varying in number to the clutch from one to many. Possibly in some of the lower types of exist-

�� � P OP ULAR MIS CULL ANY.

��711

��ing birds such an ancestral trait has persist- ed. In certain instances where birds lay ex- posed to view either white or light-tinted eggs, or those not otherwise protectively colored, they have the habit of covering the clutch over with leaves, etc., when the in- cubating parent temporarily quits the nest. The eggs of birds, irrespective of the char- acter of the coloration of . their plumage, which habitually lay in inaccessible places, are often either white or light-tinted and ex- posed to view. Both the age of the bird and the physical condition of its constitu- tion at the time of laying an egg have their influence upon the coloration of its shell. Changes in the constitution may be due to external causes, as fright, etc. ; or to inter- nal causes, as disease, etc. The richest-col- ored eggs of any species (that lay other eggs than white ones) are laid by that species at its prime. The positions of th egg as it passes down the oviduct, as well as its mo- tions, affect the pattern of its markings.

The Great Siberian Railway. Of the

'total length of nearly four thousand seven hundred miles of the great Siberian Railway, the rails are already laid over one thousand and six miles, or sixty-eight miles more than one fifth of the whole distance. In this are counted the distances built from the eastern end at Samara to the Irtysh opposite Omsk, and at the western end from Vladivostok along the Usuri River. There was some doubt at first whether the road should fol- low the northern route, where a railroad is already built along the old caravan road, through Ekaterinburg to Tyreman, on the Tura, or on the southern line where the ad- vantages of population and traffic in central Siberia are more tempting. The southern route was chosen, and the railway, starting from Samara, passes through the densely peopled parts of south Siberia to Ufa, at the junction of the Byela and Ufa Rivers, thence to Zlatoust, the center of the great iron and gold mining district of the southern Urals, when it crosses the mountains, and to Chlya- bisk, on the borders of the prairies of south- west Siberia ; thence to Omsk, the present terminus, Tomsk, Krasnoyarsk, Irkutsk, Chita, and the southern coast of Lake Baikal. Here a way will have to be cut through the Tocky crags that rise abruptly from the wa-

��ters of the lake ; and between Chita and the Amur a series of parallel ranges will have to be crossed. Owing to the unfavorable char- acter of the region for population, the rail- way between the Amur and the Usuri will probably remain for some time to come a mere strategic line.

Climate of the City of Mexico. A report by the Director of the Meteorological Observ- atory of Mexico, published by the director, Senor M. Barcena, on the climate of that city, gives the mean annual temperature as 59Y, and the monthly means as ranging from 53-6 in December to 64-6 in May. The absolute maxima in the shade vary from 73-4 in December to 88-9 in April, and the absolute minima from 28*9 in December to 46-8 in August and September. The great- est daily range amounted to 41 in the month of March. The mean annual rainfall amounted to 23*8 inches, the wettest months being June and September. The greatest fall in one day was 2 - 5 inches in August, 1888. The prevalent wind is northwest, which blows during most of the year, and that is the coldest and wettest quarter. The strongest wind blows from the northeast. The greatest hourly velocity observed was about fifty-six miles an hour. The report is based upon the hourly observations of the sixteen years, 1877 to 1892.

Lilian Island Snake. Peculiar to the Luchu Islands is the poisonous Trimeresurus snake, called habu by the natives, which is described by Prof. B. H. Chamberlain, of the Imperial University of Japan, as being four or five feet long by two inches in diameter, and u3 an object of universal fear and hatred. It springs out at passers-by from the hedges, where its habits lead it to lie in wait for birds, and actually enters houses, so as to make it perilous during the warm season to walk about the house at night except with a lantern. The general result of bites that do not bring on death is lifelong crippling. Re- wards are offered by the authorities for the bodies of these snakes, dead or alive, and the villagers go out in the woods to secure them. Yet the number does not seem to diminish perceptibly, and at least one case is recorded within recent years of a village hav- ing been abandoned by its inhabitants be-

�� � 712

��THE POPULAR SCIENCE MONTHLY.

��cause they could not cope with these enemies. Sea snakes are common on some of the is- lands, of three species, two of which are harm- less, while the bite of the other is poisonous. These sea snakes are highly prized, as vipers are in Japan, and are used as food by the rich and, to a smaller extent, as medicine by the poor.

Smoke. The following, from the Amer- ican Engineer and Railroad Journal, seems worthy of mention : A mistaken idea exists as to the amount of actual carbon con- tained in those dense masses of smoke which are seen rising from the tall stacks of manufacturing and other large plants. By passing through water the gases aris- ing from a furnace burning bituminous coal, and weighing the solid particles retained or precipitated, it has been proved, it is claimed, that they amount to less than one sixth of one per cent of the total amount of coal consumed. It is not strange that a different idea is entertained of the quantity of actual carbon seemingly going to waste, when the wonderful coloring power of the finely divided particles of carbon is consid- ered. To prove this it is only necessary to try the well-known experiment of smoking a bit of glass with a candle, and then mixing up with a palette knife a portion of the coloring matter thus secured with a drop or two of gum arabic. A very small portion of this mixture will color many quarts of water. The actual carbon contained in the smoke itself is inappreciable, but the unconsumed invisible gases invariably associated with the smoke are considerable in quantity and indicative of a financial loss much larger than is gener- ally known.

Therapeutic Hypnotism. The unmis- takable signs of the failing belief and in- terest in hypnotism as a curative agent, and its relegation to the field of curious if not pathological psychology, is pointed out in the editorial columns of the last Lancet. The two deciding questions, about which controversy has raged, have been, first, Are hypnotic phenomena physiological or patho- logical ? and, secondly, Has the induction of hypnosis any therapeutic value ? A study of the most successful hypnotic subjects seems to indicate that the phenomenon is really a

��morbid one, and "associated with feebleness of will and unusual impressionability," and as regards its therapeutics, while it may be of some value in certain functional nervous diseases, such as hysteria and neurasthenia, there are other methods of producing the same effect which have none of the dangers, both moral and physical, with which hypnosis is fraught.

Diphtheria and Milk. A curious epi- demic of diphtheria following a sore throat, caused by drinking a certain milk, is recorded in the British Medical Journal. On the out- break of the sore throat the milk and its surroundings were closely examined : some of the cows had sore teats ; but no disease in the throats of either cows or milkers could be discovered, and there were no Loef- fler bacilli in the throat scrapings from the patients. Upon boiling the milk before using, the epidemic promptly subsided. But within less than a week a true epidemic of diphtheria appeared among these same peo- ple, and, although careful investigation was made, no source of secondary infection could be discovered. It seems probable that the throat trouble caused by the milk laid the foundation for the diphtheritic bacillus. The outbreak was a very mild one, only one death occurring.

Physical Measurements of School Chil- dren. In J. Allen Gilbert's researches on the mental and physical development of school children, the results in the observations of muscle sense, or sensitiveness to weight, showed a gradual increase in ability to dis- criminate, from six to thirteen years of age. At thirteen there was a gradual falling off and then another gain. Boys and girls, con- sidered together, gradually increase in ability, but when they are considered separately, marked differences of sex appear. At six years the considerable difference is in favor of the boys ; at seven both sexes have the same ability. From this on both gain with equal pace to the age of thirteen, with the ex- ception of an abrupt falling off for boys at eleven. From thirteen to seventeen the dif- ference again becomes manifest in favor of boys. Ability to distinguish different shades of the same color increases with age. The balance of advantage in this test is slightly

�� � POPULAR MISCELLANY.

��713

��in favor of the girls. Voluntary motor abil- ity is measured by the number of taps the child can make in five seconds. The average child at six years taps 20 - 8 times in that in- terval. From this there is a gradual increase till the age of twelve, when the rate is 29 - 9 taps. This is lowered one tap at thirteen after which the increase is resumed and reaches a maximum at seventeen, when the rate of tapping is 33'8 in five seconds. The rate is higher for boys than for girls. After tapping for forty-five seconds fatigue enters into the results very noticeably. The fa- tigue is most marked at the age of eight and least marked at fifteen. Boys tire more quickly throughout in voluntary movement than girls, but as they act more vigorously it can hardly be said that they tire more easily. Boys have a larger lung capacity than girls throughout. Girls become nearly stationary in it at twelve, but boys do not begin their most rapid growth till they are fourteen years of age. The time of simple reaction de- creases with age. The results, when consid- ered for girls and boys separately, show marked differences in sex. The bright chil- dren react more quickly than the dull. But all react in about the same time just before those ages eleven and sixteen in which changes of growth manifest themselves. In the test for reaction with discrimination and choice, ability increased and the length of time required decreased with advance in age. This test implies more complicated mental activity, and the influences that affect mental life show themselves more plainly in the curve representing such development.

Uses of the Sand Blast. It appears from an account of the applications of the sand blast given by Mr. J. J. Holtzapffel, in the English Society of Arts, that glass is almost immediately depolished by the blasts now in use, and only a little time is required to pierce and cut holes through sheet and plate glass. Stone, marble, slate, and granite are equally amenable to its action. Iron, steel, and other metals have their surfaces easily reduced and smoothly or coarsely granulated, according to the force and abrasive powder used. The abrasive need not be harder than the metal to which it is applied. The blast is used for frosting and decorating glass, the labeling of graduated measures, for remov-

��ing hard scale from castings and forgings, for carvings and inscriptions in intaglio or relief on stone, slate, and granite, for delicate draw- ings for lithography, for removing fur and deposits in tubs and tanks, for cleaning off accumulations of paint and dirt within iron ships, for decorating buttons, for piercing the holes in glass ventilators, for marking pottery and ornamental tiles, for refacing grindstones, emery and corundum wheels, for granulating celluloid films for photography, and on wood to bring out the grain in relief, and, latterly, for blocks for printing.

Tnberenlosis in Meat. The Koyal Com- mission appointed in July, 1890, to inquire into the effect of food derived from tubercu- lous animals on human health has reported, as the result of its five years' investigations, that it has obtained ample evidence that " food derived from tuberculous animals can produce tuberculosis in healthy animals. The proportion of animals contracting tuberculo- sis after experimental use of such food is different in one and another class of animals ; both carnivora and herbivora are susceptible, and the proportion is high in pigs. In the absence of direct experiments on human sub- jects we infer that man also can acquire tuberculosis by feeding upon materials de- rived from tuberculous food animals. The actual amount of tuberculous disease among certain classes of food animals is so large as to afford to man frequent occasions for contracting tuberculous disease through his food." The commission thinks it probable that an appreciable part of the tuberculosis that affects man is obtained through the food. Tuberculous disease is observed most frequently in cattle and in swine. It is found far more frequently in full-grown cat- tle than in calves, and with much greater frequency in cows kept in town cowhouses than in cattle bred for the express purpose of slaughter. It is but seldom found in the meat substance, but principally in the organs, membranes, and glands. It is found in the milk of cows when the udder has been at- tacked by tuberculous disease, and seldom or never when the udder is not diseased. In the milk it is exceptionally active in its oper- ation upon animals fed either with the milk or with dairy produce derived from it. Pro- vided every part that is the seat of tubercu-

�� � 7H

��THE POPULAR SCIENCE MONTHLY.

��lous matter be avoided and destroyed, and pro- vided care is taken to save the actual meat substance from contamination by such mat- ter, a great deal of meat from animals af- fected by tuberculosis may be eaten without risk to the consumer. Ordinary processes of cooking applied to meat which has got con- taminated on its surface are probably suffi- cient to destroy the harmful quality. They would not avail to render wholesome any piece of meat that contained tuberculous matter in its deeper parts. The boiling of milk, even for a moment, would probably be sufficient to make it safe.

Similarities in Cnltnre. Prof. 0. T.

Mason closes a somewhat critical discussion of similarities in culture on which, he sug- gests, more is sometimes built than can stand with the conclusion that such simi- larities may arise through a common hu- manity, a common stress, common environ- ment, and common attributes of Nature ; through acculturation, or contact, commerce, borrowing, appropriating, between peoples in all degrees of kinship ; and through com- mon kinship, race, or nationality. Generic similitudes arise by the first cause; special and adventitious similarities by the second cause ; and the more profound, co-ordinated, real, and numerous similarities by the third cause. Similarities are partly natural, such as sounds of animals, forms of pebbles, qualities of stone, clay, and the like, but most of tbem are fundamentally ideal. Where the same idea exists in two areas, a simple one may have come to men independently. One containing two or more elements in the same relation and order is less likely to have so arisen, while a highly organized idea could not often have come to two men far removed from one another. Furthermore, a complex idea is never the progeny of a sin- gle mind, and that embarrasses the question further. The generic and adventitious simi- larities are most striking and most frequently called to notice. The error is in taking them for profound and real similarities. Those similarities that are imbedded in the life of peoples and logically co-ordinated with the annual circle of activities are of the fam- ily and stock, and beyond any reasonable doubt proclaim the people to be one. " Fur- thermore, they exist for the trained and

��patient eye and hand ; they elude the gaze of the superficial observer. The identifica- tion of them is the reward of long years of patient research, and the finder is the dis- coverer of a pearl of great price."

Electric Cooking Vessels. The first at- tempt in practice to devise vessels for cook- ing by electricity was made about four years ago by a Mr. Carpenter, an American, who developed Lane Fox's idea of surrounding the vessel by a coil of insulated wire through which a current should be passed. He at- tached the resistant wires to the surface of cast-iron plates by an enameling process. Some defects appeared in his method, among which was the liability of the enamel to crack, whereby the wire was exposed to the oxidizing action of the air. These difficul- ties have been overcome by the English manufacturers Crorapton & Co., who have found a safer enamel and substituted a nickel-steel wire as being better adapted to endure the action to which it is exposed than the wire that was used before. By specially adapted methods they are able to apply the wire in somewhat complicated patterns to the surface of any metal plate, and to insu- late it therefrom in a very thorough and permanent manner. They exhibit, con- structed on this plan, a simple electric heater a circular plate mounted on short legs, to the under side of which wire is ap- plied and fixed by the enamel, while the upper side is ground flat and polished a frying pan, saucepan, kettle, griller, hot iron, and radiator. The radiators have been found convenient, safe, and economical for heating theaters and efficient in preventing the deposition of frost on shop windows.

Formation of Stalactites. Describing the deposition of carbonate of lime in stalactites and stalagmites, Mr. George P. Merrill, of the United States National Mu- seum, says that water filtering through a rock roof, by virtue of the carbonic acid it contains, is enabled to dissolve a small amount of the lime carbonate, which is again de- posited when the excess of carbonic acid escapes either through relief from pressure or through the evaporation of the water. Conditions favorable to either process are furnished by the water filtering through the

�� � POPULAR MISCELLANY.

��7'5

��roof of a cave and dripping slowly to the floor beneath. In cases where the water filters sufficiently slowly or evaporation is cor- respondingly rapid, the deposit of lime car- bonate from the roof takes at first the form of a ring around the outer portion of the drop, a natural consequence of the evapora- tion of a suspended drop of liquid. This process may go on until the ring becomes prolonged into an elongated cylinder or tube, the diameter of which may not exceed five millimetres, though usually ranging from five to ten, and of all lengths up to fifty centi- metres. In exceptional cases this length may be exceeded, but owing to the delicacy of the material the stalactite usually breaks from its own weight and falls to the floor before the length of -even ten or fifteen cen- timetres is reached, to become imbedded in the stalagmitic material there forming. Lengths of even these dimensions are com- paratively rare, for the reason that the tube becomes shortly closed, either as its upper or lower end, usually the upper, and all growth from the extremity alone ceases, sub- sequent depositions being wholly exterior and taking place in the form of concentric coatings of the carbonate on the outer sur- face and at the same time from the top. There is thus formed around the original tube a compact cylindrical mass, in its typical form, constricted at the point of attachment, but thickening rapidly and then tapering gradually into an elongated cone. The ma- terial of the stalactites is not always wholly carbonate of lime, but in some cases thin intervening coats of iron disulphide are met with. Through a kind of crystallization the material sometimes undergoes a distinctly fibrous arrangement, but oftentimes the structure is granular throughout.

Snake-bite Antitoxine. At a recent meeting of the Royal Society of Edinburgh Prof. Fraser delivered a lecture embodying some extremely valuable and interesting data obtained by him during several years of ex- perimental work on an antidote for snake poisons. The principles utilized by him are similar to those employed in the antitoxine treatment of diphtheria and in vaccination for smallpox. He first immunized an animal by repeated small doses of the snake poison, slowly increasing the quantity, until the ani-

��mal was taking at a single dose many times the minimum lethal amount for a non-im- munized individual. He then injected into another animal some of the blood serum from the immunized case, and found that this prevented any ill effects from a subse- quent injection of venom. Still a third ani- mal was given an injection of pure venom, and, when distinct symptoms of poisoning appeared, was treated with the immunizing serum, with the result that the symptoms of poisoning disappeared and no ill effects fol- lowed. When it is remembered that in British India alone there are each year from eighteen to twenty thousand deaths caused by snake-bite, the great beneficence of this discovery is apparent. Prof. Fraser is at present immunizing a horse, but is having some trouble, owing to the difficulty of pro- curing the snake- poison in sufficient quantity.

Unsanitary Filters. For many years be- fore any positive connection was established between typhoid fever and a specific micro- organism it was known that this and other diseases were in some way connected with the composition of the drinking water pre- viously consumed by the patient. By chem- ical analysis it was found that in almost all such cases the water contained an excess of organic matter ; it was accordingly inferred that removing the organic matter would cor- rect the trouble and obviate any further danger; and filters were made with this end in view. It is now known, however, that the danger from waters containing much organic matter lies not in the organic matter per se, but arises from the fact that a large amount of organic matter attracts and feeds a pro- portionately large number of bacteria. It has been proved experimentally that after a filter of this class has been in use for some time, water, in passing through it, becomes much richer in bacteria, and even that ster- ilized water passed through it is found swarming with micro-organisms. The filter collects the organic matter from the water and with it some of the bacteria. This mass of organic matter serves as an admirable culture medium ; as the bacteria multiply, they are taken up by the water as it passes through the filter, so that, instead of serving as a safeguard against disease, such filters are really disease breeders. In order to be

�� � 716

��THE POPULAR SCIENCE MONTHLY.

��effective, a filtering apparatus must either remove or destroy any micro-organisms con- tained in the water.

Color Photography. At a recent soiree of the Royal Society, in London, Dr. Joly, of Dublin, exhibited some photographic trans- parencies upon glass plates representing va- rious objects in their natural colors. The subjects photographed were especially chosen because of variety of color and delicate shading, and were reproduced with great naturalness and fidelity. The results were accomplished by the use of a finely ruled glass plate, two hundred to three hundred lines to the inch, each three lines being a complete color series, consisting of an orange- yellow line, a greenish-yellow line, and a blue-violet line, these colors being repeated over and over again. The lines are ruled with colored inks, made up of gum and gelatin mixed in certain proportions, on a gelatin-coated plate. The plate to be ex- posed is placed in contact with this color- screen, and only exposed to light which has passed through the latter ; an extra-long exposure is necessary, owing to the partial opacity of the color-screen. The plate is then developed in the ordinary way. The color-screen is now again placed against the negative, and when the two are held up to the light, if the color-screen is placed just as it was when the exposure took place, an accurately colored reproduction of the origi- nal scene appears. The process is so simple and inexpensive that it will probably come rapidly into general use.

The Yalne of Object Lessons. In a re- cent educational circular we find the follow- ing on object teaching : " To sum up the main value of object teaching, there are three principal uses : The first and most im- portant is to teach the children to observe, compare, and contrast ; the second is to im- part information ; and the third is to re-en- force the other two by making the results of them the basis for instruction in language, drawing, number, modeling, and other handi- work. There are, however, other important uses of good object teaching. It makes the lives of the children more happy and inter- esting by opening up an easily accessible and attractive field for the exercise of brain,

��hand, and eye; it gives the children an op- portunity of learning the simplest natural facts ; and directs their attention to external objects, making their education less bookish. It further develops a love of Mature and an interest in living things, and corrects the tendency, which exists in many children, to destructiveness and thoughtless unkindness to animals, and shows the ignorance and cruelty of such conduct. The value of the services which many animals render to man should be dwelt upon, and the importance of kindly treating them and preserving them should be pointed out. By these means, and in other ways, good object teaching may lay the foundation for the right direction of the activity and intelligence of the children throughout the whole school."

Sunlight and Pictures. The question of preventing or mitigating the fading of pic- tures and pigments has been attacked in earnest and in a practical way by Captain W. de W. Abney, who finds that fading in the course of time is one of the inevitable effects of the operation of ordinary sunlight. Pictures can not well be taken from the light, so the next best thing is to discover which of the solar rays do the most damage, and to mitigate their effects as far as pos- sible. The violet rays prove to be most ac- tive in producing fading. If we can elimi- nate the majority of these rays from white light without appreciably altering the fresh- ness of the colors viewed in such light, we shall practically have prolonged the life of a picture. A variety of experiments made with different pigments tell us that the loss of the violet of the spectrum is practically no loss at all. Even with white light the loss is unnoticeable. If we form a patch of light composed of all the colors except the violet, we shall notice but little change from the pure white that is alongside of it. The case becomes simpler yet when we find that the blue-green light and the yellow light of the spectrum superposed give substantially white. A blue-green glass and a yellow glass interposed against the sunlight practi- cally cut off all the violet, while they give passage to the rays that form white. Cap- tain Abney therefore solves his problem by using glasses of these colors for the window- glazing of hjs gallery. Making the windows

�� � POPULAR MISCELLANY.

��717

��and skylights with alternate strips of these colors, he has a light which when diffused blends into a practical white that allows the pictures to be seen as under usual conditions, while the danger of fading is made the smallest possible.

Pimento. Pimento, allspice, or Jamaica pepper is the dried berry of the pimento tree of Jamaica, which grows to the height of twenty or thirty feet ; and the markets of the world are wholly supplied from this source. The tree will not grow on the coast lands, but flourishes best on the mountains of the interior of the island. The tree from the leaves of which the aromatic principle of bay rum is extracted (Pimento acris) is also a native of Jamaica, but its cultivation has been neglected. * The pimento tree is a plant of paradoxes. It is not friendly to cultiva- tion, so that it has not been found possible to rear healthy plants from the seeds by arti- ficial planting ; and the stock can not be successfully increased by slips. The seed- lings thrive, however, when the seed has been digested by a bird, and this source of supply is largely relied upon. When it is desired to stock land with pimento, the trees growing upon it are cut down and their trunks are left lying where they fell. The bushes and the brush are burned, and the ground is planted with provision crops. Aft- er the lapse of some months, young pi- mento plants may be seen springing from the soil in various places. Care must be taken to keep cattle from them, for they are very fond of the spicy leaves and would de- stroy the young plants. After two or three seasons cultivation is stopped and the grass is allowed to grow. Cattle are permitted to pasture on the land after the trees have grown out of their reach. The planter has now only to keep the land clear of brush and to gather his crops. The harvest begins in August, just before the berries turn black. One of each party of pickers climbs the trees, breaks off the berry-bearing branches, and throws them down to his com- rades, who strip off the berries. The tree is left in a ragged condition, and the process seems to be a barbarous one, but it is said to be best for the trees. If they are pruned, the branches cut die to the main stem ; while if the limbs are broken off they shortly send

��forth new shoots ; and it is claimed that the year's yield depends largely on the extent to which the limbs have been broken the pre- vious season. The crop is next cured by drying, winnowed, and prepared for the market. Pimento holds the fifth place of importance in the exports from Jamaica, being exceeded in value only by sugar, rum, coffee, and fruit ; but the demand for it is declining, and its importance is therefore growing less.

The Tricks of Worthless Companies.

A report lately published by the English Board of Trade on the working of the Com- panies Winding-up Act during 1893 reveals some startling facts indicating mismanage- ment. Winding-up proceedings were begun during the year against more than a thou- sand companies out of a total of 16,104 in England and Wales, while 2,332 new com- panies were started. The whole number of liquidations during the two years 1892-93 was nearly equal to one half of the number of companies formed during the same peri- od. Besides these, a large number of new companies annually prove abortive and cease to exist, or, if their names are not taken from the register, remain there as moribund companies. From the figures of the past year it would appear that nearly two thirds of the companies formed fail to establish themselves as permanent enterprises. The report exposes the manner by which fraudu- lent or mistaken estimates have enticed sim- ple and believing investors to risk and lose their savings. Malpractices begin with the prospectus and continue till liquidation. One case is cited in which the property sold to the company for two hundred and fifty thou- sand dollars had been bought a few months before by the promoter for three thousand dollars. In another case the interest in the publication of a periodical was bought by the promoter in June for fifteen hundred dollars in cash, and was sold in August to a company, practically consisting of himself, for fifteen thousand dollars in cash and fif- teen thousand dollars in debentures, with a view of ultimately disposing of it to the public at a price based upon these figures. In another instance a small and worthless business was represented as a business in the various centers of industry in England

�� � and Ireland, firmly established and very lucrative, and, a safe investment, which would, according to the report of an expert sent out with the prospectus, return, taking the previous year's business as a criterion, a profit of fifteen per cent. The worst of the matter is that the report confesses that the statements, false as they were, were not of such specific character that they could be made the subject of criminal indictment.