Popular Science Monthly/Volume 2/March 1873/Miscellany

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Antiquity of Civilization.—M. Oppert read an essay at the Brussels Congress, to show, from the astronomical observations of the Egyptians and Assyrians, that 11,542 years before our era man existed on the earth at such a stage of civilization as to be able to take note of astronomical phenomena, and to calculate with considerable accuracy the length of the year. The Egyptians, says he, calculated by cycles of 1,460 years—zodiacal cycles, as they were called. Their year consisted of 365 days, which caused them to lose one day in every four solar years, and, consequently, they would attain their original starting-point again only after 1,460 years (365 x 4). Therefore the zodiacal cycle ending in the year 139 of our era commenced in the year 1322 b. c. On the other hand, the Assyrian cycle was 1,805 years, or 22,325 lunations. An Assyrian cycle began 712 b. c. The Chaldeans state that between the deluge and their first historic dynasty there was a period of 39,180 years. Now, what means this number? It stands for 12 Egyptian zodiacal cycles plus 12 Assyrian lunar cycles.

These two modes of calculating time are in agreement with each other, and were known simultaneously to one people, the Chaldeans. Let us now build up the series of both cycles, starting from our era, and the result will be as follows:

Zodiacal Cycle. Lunar Cycle.
1,460 1,805
1,322 712
———— ————
2,782 2,517
4,242 4,322
5,702 6,127
7,162 7,932
8,622 9,737
10,032 11,542

At the year 11542 b. c. the two cycles came together, and consequently they had on that year their common origin in one and the same astronomical observation.

A Plant-Battery.—Under the heading "Arceuthobium shedding its Seed," L. A. M., in the Bulletin of the Torrey Botanical Club, gives the following account of what deserves to be called a vegetable mitrailleuse: "I visited the swamp in Warrensburg, the first week in October. I found its female plants of Arceuthobium nearly all gone. Every effort that I made to cut twigs from the matted clumps, where the colonies of these strange parasites grow, brought them down in showers. Fearing that I should fail to get plants with full seed-vessels, I picked a single plant with vessels much swollen. While holding it gently between my thumb and finger, to observe it more closely, I felt the tiniest recoil of the capsule, and the seed struck me a smart blow in the face. I gathered another, and another, and each pretty little bomb went off with a force that must have carried it several feet away. The seed flies out of the base of the capsule, instead of the top; but its position on the plant makes that the top, as, when ripe, the vessels hang with the true summit turned downward. I found the seeds and empty seed-vessels lodged all about on the branches. The plants which have ripened seed fall off nearly all together: those which have not blossomed, or have failed to be fertilized, probably remain for another year. When the seeds are being sown, there must be quite a brisk bombardment going on for several days. Isolated colonies of Arceuthobium in forests may have been planted by seed adhering to the feet of birds."

Government Telegraphy.—The first number of the London Telegraphic Journal, in a leading article on Government telegraphy, has some very pointed criticisms on the working of the new system in England. The end sought by the Government in assuming control of the telegraph interests of the country was, by cheapening the rates and extending the lines, to bring the advantages of the system within the reach of a larger number of people, expecting thereby, just as in the case of the post-office, to derive sufficient income for the maintenance of the lines by the increased patronage that cheap rates would secure. As was anticipated, a large increase of business has resulted; but this very increase promises to defeat the chief advantage which the telegraph is designed to afford, viz., speed of communication. "Speed," says the Journal, "is the very essential of the telegram; it is its raison d'être; therefore, there is no good in reducing the charge for this convenience, if the convenience itself vanishes. It becomes, in fact, much more expensive. We now pay a shilling for a telegram, when a penny stamp, or even a half-penny card, would have sufficed. In former days a telegram was an outlay, certainly, but we paid much for a speed that we obtained. Many would still pay as much for the same advantage, but find they pay a reduction for a ghost of it." The writer does not despair of a remedy for this state of things, but says that the reticence of the authorities concerning the details of their management prevents the suggestion of any means of relief. The case adds one more to the already long list of examples where the Government plays the part of an obstructive.

Silica as a Basis of Paint.—There was lately discovered in North Wales a deposit of almost pure silica, several feet in depth, which on analysis shows the following constitution: silex, 79 parts; water, 13; oxide of iron, 3; alumina, 4; magnesium, 1. In the manufacture of crystal glass and porcelain this discovery is of considerable interest, but it is perhaps still more valuable as furnishing an excellent fire-proof and water-proof paint. When taken from the bed the silica is freely washed in water, and on being dried it becomes brilliantly white, and is then an impalpable powder. In preparing it as a base for paint, the water is dried out. It mixes readily with pigments and oils, is worked with the greatest ease, and resists the action of acids and of heat. When perfectly dry, the paint is extremely hard and polished on the surface. Applied on the inside or outside of houses, it excludes damp.

White Spots on Photograph Proofs.—Ever since the invention of photography on paper, says the Moniteur Scientifique, photographers have been trying to discover the cause of those white points which so frequently appear on their proofs, destroying their value as works of art, and rendering them unsalable. It is commonly supposed that these spots are owing to a defect in the paper—the presence in it of hypochlorite of soda, used by the paper-maker for bleaching purposes. But, as the manufacturers claim that chemical analysis fails to detect in their goods the faintest trace of the hypochlorite, M. Ernest Baudrimont set himself to discover where the fault lay. He first made a thorough analysis of the paper and the size used in taking photographs, but without finding there the cause of the spots. One thing, however, he did discover, which helped him to find the true solution of the problem, and this was that the spots always occurred on the face of the picture, but never on the back. He next artificially produced some spots on a perfect proof, by the employment of the hypochlorite of soda, the hyposulphite of soda, and the cyanide of potassium. After drying the pictures, he applied to the spots a solution of nitrate of silver. It was found that the white spots produced by the hypochlorite and by the cyanide remained totally unchanged, whereas those produced by the hyposulphite very rapidly changed, first to a yellow, then to a brownish tint. M. Baudrimont next touched with the silver solution spots appearing spontaneously on some pictures, and the result was, that at first a yellow point, which soon turned to brown, appeared in the centre of the spots, finally extending over their entire surface. Hence, the author concludes that the white spots occurring in photograph proofs are entirely owing 10 the hyposulphite of soda, used to fix the positive impression. If the proof is not thoroughly washed after the application of the hyposulphite, or if it is dried between sheets of blotting-paper, which are impregnated with the hyposulphite, from having served the same purpose before, the white points will inevitably make their appearance.

Ancient Ferns.—At a late meeting of the Torrey Botanical Club of this city, Dr. J. Newberry exhibited a fossil fern which he had obtained from the Miocene formation in the western part of the continent. It was an Onoclea, and was not distinguishable from the recent Linnæan species, Onoclea sensibilis. This certainly carries back the lineage of our common sensitive fern to a very ancient period.

At the same meeting of the club, there was also exhibited a fine specimen of that singular plant which grows parasitic on the roots of the pine-tree, and is hence called, in the Eastern States, pine-drops. The plant is rare at the East, and seldom attains the height of two feet. The specimen exhibited was four feet high.

Our Native Birds acquiring New Habits.—In a late number of the American Naturalist, Prof. Samuel Lockwood gives an interesting account of that beautiful bird known as the golden robin, or Baltimore oriole, in connection with one of our carpenter-bees. He states that last June large numbers of these bumble-bees were found under the horse-chestnut trees, then in full bloom, in the campus of Rutgers College. The strange fact was, that every one of these insects was decapitated, and the heads were lying around with the bodies; further, it appears that every one of the headless bees was a stingless male. The professor worked out the case with much patient perseverance, and found to his surprise that this wholesale slaughter was the work of four orioles. Another fact which astonished him was, that the bodies of all these insects were empty, the viscera having been drawn out at the ring-like opening where the head had been neatly snipped by the birds. The process was to catch the bees while hovering at the ball-like opening of the flowers. After severing the head, they extracted the viscera for the sake of the honey-sac. Several very interesting considerations are brought out in the course of the article—such as the acquired taste; the birds had found out that honey was nice. Was it not singular, too, that they had learned that it could be got in such a manner? And there was also the curious fact that the bird confined its marauding to the white-headed bees, the stingless males—thus carrying on his terrible work with impunity, and almost wantonness, as it contented itself with simply the honey-bearing sac.

Prof. Lockwood also notes a curious change of habit in the kingbird. Speaking of the wonderfully plucky manner of this courageous little bird in attacking crows and other large birds, as securing the general admiration, he says that for himself that admiration has gone down to zero, as he has noticed that the bird has not any true knightly qualities, but can do some very mean things. The professor then instances a case in which a pair of robins had built a nest in a tree so near by that the process could be watched from the house. A pair of kingbirds kept all the time near, and watched progress with genuine royal indolence, and, when all was finished, with kingly impudence took possession. The rightful owners made but a feeble effort to resist this invasion. The kingbirds retained possession until their young were raised.

More than a year ago, Prof. Lockwood likewise called attention to the fact that the great butcher-bird, or Northern shrike, contrary to all precedent, had begun to visit in winter the cities where the European sparrows have become naturalized. The bird in summer collects grasshoppers, small lizards, etc., and impales them on the spines of the locust or other trees, eating them at its leisure. He notices the case in which a shrike in its winter visit gibbeted a sparrow in, the city by putting its neck in the crotch of a small branch of a larch, and then, having knocked in the top of its head, the bird extracted its victim's brains.

Paper as a Building-Material.—An English company prepare a water-proof material out of paper-pulp, or any fibrous substance, by saturating it with ammoniated copper solution—a digest of copper scraps in concentrated ammonia. This treatment dissolves the fibres and renders the paper impervious to water. A number of sheets of paper are moistened on the surface, placed on each other, and thoroughly pressed. They thus are made to adhere firmly together, and are then fashioned into the various forms required. The product may replace corrugated iron for roofing, or it may be made into columns and flutings for internal decoration. It is said to be a very durable material even when exposed to air and rain.

Bowlder-like Masses of Clay in the Long Island Drift.—An extensive excavation in the side of Harbor Hill, near Brooklyn, Long Island, has revealed the presence of detached bowlder-like masses of clay embedded in the drift. Mr. Elias Lewis, of Brooklyn, who has examined these objects, writes that they lie unbroken like bowlders of granite, and have the same rounded outline. One mass, consisting of a tough, fine-grained bluish-gray clay, was eight feet in vertical diameter, and seven feet through from side to side. Mr. Lewis is of the opinion that these masses were transported by ice and deposited in a frozen state, but adds that it is difficult to understand how they should have retained their form beneath moving water during the long time necessary for the accumulation of the layers of gravel and sand which surround them; nor is it clear how stratification of deposits could occur in water deep enough to float icebergs.

Will some one familiar with glacial deposits inform the readers of The Monthly whether similar masses of clay or earth of any kind are common in the recognized glacial drift?

Fuzi-Yama and Hakusan.—These, the two highest and most famous mountains of Japan, have lately had a new determination of their respective heights. A British officer made the ascent of Fuzi-Yama, on the 9th of September, and found, by approved and carefully-conducted methods, the height to be 13,080.32 feet, which is less than its accepted altitude, namely 14,177 feet. This same officer ascended Hakusan, being the first foreigner that has done so. His measurement makes this mountain higher than the accepted figures, which Stieler sets down at 8,178 feet. The new measurement gives 9,200 feet. Both these mountains are held sacred by the Japanese, Fuzi-Yama perhaps being specially so, as its singular name would imply, which means the "No-two-mountain;" that is, the none-such, the peerless, the inimitable. They are both volcanic mountains, with vast craters. Hakusan is snowcapped the whole year, while it may be called a snow-mountain for two-thirds of the year. It is some-times called "Siro-Yama," White Mountain, and is truly the Mont Blanc of Japan. Both mountains are yearly visited by many thousand pilgrims. This last explorer describes Fuzi-Yama as an ash-heap, with a cone of lava and clinker. The only vegetation at top were lichens. "The crater, by approximate measurement, was found to be 2-miles in circumference, and its depth about 440 feet." As the mountain is a cone, and stands by itself, it is regarded as the most beautiful mountain in the world. It would be rare to find a Japanese landscape in which the artist has not by some ingenuity introduced the peerless Fuzi-Yama.

Combustion under Pressure.—It is shown from the observations of James B. Eads, C.E., as given in the Journal of the Franklin Institute, that combustion goes on at the same rate in compressed as in free air. There is, however, this difference between the phenomena of combustion under the two conditions, that a flame is more readily extinguished in free than in compressed air. This is demonstrated by Mr. Eads's experiments with the flame of a candle under varying pressures. Thus, at the depth of 108½ feet in a shaft, the flame having been blown out thirteen times in rapid succession, it reappeared at the wick each time, except the last. At a somewhat greater depth, and under 52 lbs. pressure to the square inch, the flame was in the same way extinguished fifty-two times, with the same result. Mr. Eads's explanation is, that the abnormal pressure brings the oxygen of the air into close contact with the incandescent body, and so tends to keep up combustion; but the process is not more rapid than under ordinary circumstances, for the reason that the increased density of the air retards the movement of the gases resulting from combustion and surrounding the flame.

A Spider's Engineering.—A writer in Hardwicke's Science-Gossip saw a spider's web stretched across a small mill-stream, and attached on either side to stems of grass and other herbage. The stream was about three feet in width, and the web resembled a cart-wheel in general outline, having a diameter of at least six feet. The writer asks how "an animal that neither flies, leaps, nor swims," could accomplish such an engineering feat. But is it true that the spider does not swim or leap? In fact, the animal can run on the surface of water, can leap from place to place, and can float after the manner of Mr. Home the medium. It can even dive in water. But, further, it can swing like a pendulum, suspending itself like a thread from some elevated point. The writer in Hardwicke does not tell whether there was any object near the web on either margin of the stream of sufficient height to allow of the animal's so swinging from one side to the other.

Geology of the Great Plain of Morocco.—The Journal of the Geographical Society (British) has a paper by George Man, F.G.S., on the geology of Morocco, of which we give the substance. The plain of Morocco rises 1,700 feet above the sea-level, and is covered with a tufaceous crust, from a few inches to three feet thick, which is burnt for lime near the city of Morocco. The underlying rock is of similar composition but not so hard, and is called by Mr. Man a "cream-colored limestone and gray marl of cretaceous or tertiary age." Midway between Mogador and Morocco are flat-topped hills 200 or 300 feet high, covered with tabular masses of chalcedony. This suggests an enormous erosion of the plain. The author contradicts Rolfe and others who assert that snow remains upon Mount Atlas during the entire year, and says that in the first week of May snow was to be found only in deep gullies and in drifts. The mass of the Atlas range is mainly composed of porphyrites and porphyritic tufas, overlaid by cretaceous rocks, with basalts rising in erupted dikes and masses evidently post-cretaceous. Metamorphic rocks appear in rugged hills near Morocco, and white limestone on the high Atlas. Glacial moraines may be seen on this range nearly 8,000 feet above the sea, forming gigantic ridges and mounds of porphyritic blocks, in some places damming up the ravines; and at the foot of Atlas are enormous mounds of bowlders. These mounds often-times rise 2,000 feet above the level of the plain, and according to Mr. Man were produced by glaciers. Of marine drift no trace is visible.

Cross between the Zebu and European Cattle.—The organ of the Royal Prussian Agricultural Department contains a notice of some experiments on the cross between the zebu, or Indian ox (Bos Indicus), and European cattle, by W. Nathusius-Konigsborn. The doubts that have existed in regard to the fecundity of this cross led to the experiments which, the writer thinks, must forever set the question at rest. The male zebu made use of was a yearling calf from the Zoological Gardens, of the peculiar bluish-white color characteristic of the zebu race. Four heifers of Holland stock were got with calf by this animal, and produced two heifers and two bull-calves, all of which were successfully raised. Though the dams were variously colored, all the calves had white stars in their foreheads. When they arrived at suitable age, they were bred with each other and with other cattle, and both sexes proved in every respect capable of propagating their race. The amount of milk given by the half-bloods was about 500 quarts per annum. This was so much below the ordinary average as to prevent all hope of their being a desirable breed. In addition, the oxen, from which much was expected in speed and endurance, proved so incorrigibly obstinate as to defy all efforts to train them for the yoke, lying down on the smallest provocation, and in one case, where it was necessary to lead one of them a short distance, the animal died the next day, it was supposed from the effects of anger and excitement. They acted much more like half-tamed wild-beasts than like domestic cattle. The only redeeming feature was the quality of their flesh, which, in those that were sent to the butcher, proved to be excellent.

Solidifying Petroleum.—The Journal de Eclairage au Gaz describes as follows a process invented by Jordery and Paschkoff for the solidification of petroleum, thus making it more easily and more safely transportable: "First make a decoction of the root or leaves of the Saponaria officinaria, quillay, or any other substance possessed of saponific properties. Then an amount of this decoction or extract, equal to one-twentieth of the petroleum to be solidified, is placed in a vat, and the petroleum suffered to flow in upon it slowly, the whole being constantly stirred in the mean time. This process may be followed with oils in general, and with volatile oils it will prevent loss from leakage and obviate many of the dangers now attending their transportation."

Curious Phenomenon in Vegetable Physiology.—It has long been known to botanists that, occasionally, after the felling of pine and fir trees, their stumps would continue to increase in diameter, i. e., form new woody layers for several years. Dutrochet mentions some cases of extraordinary longevity in the stock of Pinus picea after the trunk had been felled. He says that, in the year 1836, a stock of Pinus picea, felled in 1821, was still alive, and had formed 14 thin new layers of wood—that is, one each year; and another, felled in 1743, was still in full vegetation, having formed 92 thin layers of wood, or one each year. This singular phenomenon was long a puzzle to botanists and vegetable physiologists. Over thirty years ago Goeppert, an accomplished botanist of Breslau, undertook an investigation of the subject. The result is published at large in the "Annales des Sciences Naturelles" for 1843. It appears that in all the cases examined by Goeppert there was a union of the roots of the fallen trees with the roots of living trees growing in the immediate vicinity, and his explanation of the phenomenon was that the stumps maintained their growth by drawing their supplies of sap from the trees with which they were thus connected. The union of roots in these cases was sometimes woody, and sometimes only by the bark of the roots. So far as observed, this anastomosis, or natural grafting, is confined to coniferous trees, and to only a few species of them, chiefly the silver-fir, the spruce, and occasionally the Scotch fir. In the London Gardeners' Chronicle of August 31st is an account of an instance of this kind of anastomosis of the roots of a larch, and a figure is given of the specimen, in which the stump and its root-connections are exhibited. The cut stump shows rotten wood in the centre, with the new wood at the circumference surging over the edges of the wound.

Although the discovery of this root-union explains some of the questions involved in this curious phenomenon, it does not explain them all; for instance, why does not the sap, which is thus robbed from the roots of the nurse-tree, pass up in the usual channels and overflow at the top of the stump, as is the case when a grape-vine or deciduous tree is cut during the active ascent of the sap? As the growth of new wood in exogenous trees takes place from the cambium, and the cambium is supposed to be the sap which has been elaborated in the leaves, what is the source of the cambium in these stumps?

It would seem as if there was here a complete contradiction of the ingenious theory of some of the French botanists that wood growth begins in the leaves or leaf-buds, and descends continuously thence to the roots, so that, in fact, wood may be considered the united mass of roots which emanate from the leaves of the plant.

The theory of De Candolle is, that the woody and cortical layers originate laterally in the cambium furnished by preëxisting layers, and nourished by the descending sap. To use the words of De Candolle, "The whole question may be reduced to this: either there descend from the top of a tree the rudiments of fibres which are nourished and developed by the juices springing laterally from the body of the wood and bark, or new layers are developed by preëxisting layers which are nourished by the descending juices formed in the leaves." The latter part of this statement, though somewhat vague and unsatisfactory, probably involves the true theory of the formation of wood. The preëxisting layers mentioned in De Candolle's statement include the medullary rays which reach the circumference. These medullary rays are composed of cellular tissue derived from the pith, and, like it, are capable of indefinite extension by cell-multiplication.

The primary state of all the tissues of the plant is the condition of simple cells, each of which is, in a certain sense, an independent body, having its own life-work and history in the complicated mass of which the tree is composed. All extension of the tree in any direction is made through the medium of cell-growth and cell-modifications, and, wherever there is cellular tissue in a state of vitality, there may be cell-multiplication whenever material for growth, i. e., sap in different stages, is brought into contact with such tissue.

In the case of the pine-stumps alluded to, the medullary rays of the recent wood retain their vitality, and, when the sap rises, it is transmitted through these rays and through the interspaces of the woody matter to the surface beneath the bark, these being appropriated to the organization of new cells whose walls are thickened by continuous secondary deposits, as in the normal formation of woody tissue. Of course, the amount of this woody formation will be limited, from the deficient supply of sap and want of concentration which it would obtain by passing through the leaves.

Puncturing the Pericardium.—The pericardium, or membranous sac surrounding the heart, sometimes becomes so filled with liquid that the movements of that organ are impeded. This is called dropsy of the heart. The surplus fluid may be relieved by the introduction of a trocar into the sac, but the operation is regarded as extra hazardous. Dr. Chairou, of the Paris Academy of Medicine, has tried a new method of treating the disorder in question. A young soldier just recovered from a pleurisy was found presenting all the symptoms of dropsy of the heart. The physician made a puncture into the pericardium with a capillary needle, and sucked out a considerable quantity of thick sero-sanguineous liquid, which soon became coagulated. The following morning the patient was pacing the corridors of the hospital in the very best of spirits.

Slag as a Building-Material.—"What shall be done with the slag?" is always a very urgent question for the proprietors of iron-works. Many are the plans which have been proposed for the utilization of this waste material, but, if we are to judge of their value by the amount of slag utilized, it must be confessed that they do not help to answer the iron-manufacturers' question. And yet many of the processes for the conversion of slag into a material for building would seem to promise very fair results. Mr. S. Egleston lately read a paper before the American Institute of Mining Engineers, in which he gives a history of these processes, stating at the same time, in a few words, the salient peculiarities of each. After recounting the failures which attended the first efforts, the writer sets forth the process followed in Königshütte, Silesia. There the slag is run from the furnace into a hemispherical basin on wheels, the bottom being strewed with sand or fine coke-dust to the depth of an inch. It is then drawn to the place where it is moulded into bricks. The slag and sand having been mixed together till most of the gases have escaped, the whole is pressed into a mould, and punctured frequently to let out the gas. A close-fitting cover then compresses it. The red-hot brick is next taken to the kiln, covered with powdered coal, and left to anneal. Four men make 500 bricks in five hours. In Silesia these bricks cost 25 per cent, less than ordinary bricks. The lead-slag of the furnaces in the Hartz Gebirge gives bricks of inferior quality, being very brittle. A Belgian engineer, M. Sepulchre, was the first to successfully transform slag into a stone which could be generally used. He caused the slag-channels to terminate in an excavation, the sides of which had an inclination of 30°. This steep inclination causes the section of the pits to increase very rapidly, allowing the solid crust on the surface of the liquid slag to rise with it without being attached. The mass takes from five to ten days to cool. The product is a stone which, rather soft at first, grows hard on exposure to air. Slag suitable for such treatment should contain from 38 to 44 per cent. of silica. Experiment shows that stone of this kind made from the slag coming from white iron can bear a pressure of 242 kilogrammes (500 pounds) to the square centimetre (one-third of an inch) without fissure. If from gray iron, it will not crush at a pressure of 405 kilogrammes. It is, therefore, stronger than the best marble.

Antiquity of Man in America.—The discoveries that are constantly being made in this country are proving that man existed on this continent as far back in geological time as on the European Continent; and it even seems that America, really the Old World geologically, will soon prove to be the birthplace of the earliest race of man. One of the late and important discoveries is that by Mr. E. L. Berthoud, which is given in full, with a map, in the "Proceedings of the Philadelphia Academy of Sciences for 1872," p. 46. Mr. Berthoud there reports the discovery of ancient fireplaces, rude stone monuments, and implements of stone in great number and variety, in several places along Crow Creek, in Colorado, and also on several other rivers in the vicinity. These fireplaces indicate several ancient sites of an unknown race differing entirely from the mound-builders and the present Indians, while the shells and other fossils found with the remains make it quite certain that the deposit in which the ancient sites are found is as old as the Pliocene, and perhaps as the Miocene. As the fossil shells found with the relics of man are of estuary forms, and, as the sites of the ancient towns are on extended points of land and at the base of the ridges or bluffs, Mr. Berthoud thinks the evidence is strongly in favor of the locations having been near some ancient fresh-water lake, whose vestiges the present topography of the region favors.—American Naturalist.

Effects of Coal-Gas on Plants.—Some of our readers will remember that, in Philadelphia, a few years ago, a florist, Mr. Thomas Robertson, had his plants destroyed by gas escaping from the street mains. He applied to the city for damages, but judge and jury decided that coal-gas would not injure plants. Since that time reports have been given of experiments by some learned Frenchman, who also decided that no injury resulted, and now it is said experiments have recently been made in Berlin to ascertain the effect of coal-gas upon the roots of trees exposed to its influence. Three trees were selected, two limes and a maple, and, after seventy days, the gas was cut off, to see whether the trees which had become blasted would recover. One of the lime-trees again put forth foliage, but exhibited evidences of ill health, while the remaining two trees were killed. That part of the earth which was compacted around the roots appeared to transmit most rapidly the poison of the gas. We suppose there is no one who has had any unbiased experience in the matter but knows that coal-gas will destroy plants in the manner stated. Those who have had no experience had better take care to guard against it.—Gardener's Monthly.

Cromlechs in Algeria.—The Cromlechs (dolmens) of Algeria was the subject of an address made by General Faidherbe at the Brussels International Congress. He considers these structures to be simply sepulchral monuments, and, after examining five or six thousand of them, maintains that the dolmens of Africa and of Europe were all constructed by the same race during their emigration from the shores of the Baltic to the southern coast of the Mediterranean. The author does not, however, attempt to explain the existence of these monuments in other countries—Hindostan, for instance, and America. In Africa, he says, cromlechs are called tombs of the idolaters—the idolaters being neither Romans, nor Christians, nor Phœenicians, but some antique race. He regards the Berbers as the descendants of the primitive dolmen-builders. Certain Egyptian monuments tell of invasions of Lower Egypt 1,500 years before our era by blond tribes from the West. The bones found in the cromlechs are those of a large and dolichocephalous race. General Faidherbe gives the average stature (including the women) at 1.65 or 1.74 metre, while the average stature of French carabineers is only 1.65 metre. He did not find a single brachycephalous skull. The profiles indicated great intelligence. The Egyptian documents already referred to call the invaders Tamahu, which must have come from the invaders' own language, as it is not Egyptian. The Tuaregs of the present day may be regarded as the best representatives of the Tamahus. They are of lofty stature, have blue eyes, and cling to the custom of bearing long swords, to be wielded by both hands. In Soudan, on the banks of the Niger, dwells a negro tribe ruled by a royal family (Masas), who are of rather fair plexion, and claim descent from white men. Masas is perhaps the same as Mashash, which occurs in the Egyptian documents applied to the Tamahus. The Masas wear the hair in the same fashion as the Tamahus, and General Faidherbe is inclined to think that they, too, are the descendants of the dolmen-builders.

Deep-Sea Photometer.—A deep-sea photometer, or instrument for measuring the chemical power of the solar ray at great depths in water, was shown at the late London Exhibition by Mr. C. W. Siemens. A roll of sensitive paper, hermetically closed in a glass tube, is placed in a thick disk attached to the bottom of an iron frame to be dropped by a wire into the sea. In the frame is an electro-magnet. The tube is held in a dark recess till the magnet is formed, and then it springs into the light, but is withdrawn again when the electric current ceases. The actinic force of the rays is, of course, determined from the amount of darkening produced on the paper in a given time.

Cheap Hydrogen Gas.—The statement comes from Paris that a Mr. Giffard has devised a process for the rapid production of hydrogen from water, which promises to make its use as an illuminator more economical than that of ordinary coal-gas. It is claimed that by this method hydrogen may be generated on a large scale, 18,000 cubic feet per hour, at a cost of from fifteen to thirty cents per thousand cubic feet, so that by combustion with solid refractory substances, such as magnesium, platinum, lime, marble, etc., it may advantageously compete with coal-gas for illuminating purposes.

Building-Stone and Fire.—Dr. Adolph Ott, in the Engineering and Mining Journal, treats of the resistance offered to fire by the various kinds of stone employed in building. According to this author, the presence of magnesia in limestone (magnesian limestone, dolomite) hastens the decomposition of the mass under the action of heat, the magnesia parting with its carbonic acid at the comparatively low temperature of 600 Fahr. Common limestone will stand a higher temperature without decomposition. As our Westchester and also Vermont marble is a magnesian limestone, this fact is of very considerable interest for this city. It appears that, in Chicago, as also probably in Boston, the sandstones made the most obstinate resistance to the heat. This is explained by the fact that the chief ingredient in stones of that class is quartz, a substance remarkable for its infusibility. As for granite, gneiss, mica-slate, and other rocks of the primary formation, which are commonly esteemed indestructible, Dr. Ott shows that they can make but very feeble resistance to heat. The water enclosed in such rocks accounts for their bursting and exploding when heated. Portland cement-stone is said to show extraordinary resistent power, almost equalling sandstone in this respect. Of brick walls the author is disposed to think well, provided they be honestly built of hard material throughout, and of the requisite degree of thickness.