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ually cooled down to its present condition, 'the mineral substances composing the planet must at some time have been pretty well mixed together. How then, in the process of cooling, did they come to separate, so that we find in one place masses of marble, in another place granite, and so on? It is a rather puzzling question—one of the most important questions, in fact, that confront the experts of the Carnegie establishment. So far as they have gone, they are inclined to think that, after the first thin crust of the globe had hardened, liquid rockstuffs from below were forced up through weak spots, and that the masses thus extruded, being of different compositions, formed rocks of many different kinds of one kind in one locality, of another kind in another.

Granite is one of the most familiar of rocks. Some day the experts may try to make it artificially; but certainly not for a good while yet. It is too complex,

and for this reason presents too difficult a on the spectra of distant stars. But for problem. Tiny crystals of many colors its expensiveness—for it is likely to con- and textures, from bright quartz to tinue to be extremely dear—it would feldspar, contribute to its make-up, with doubtless soon replace common glass little flakes of mica scattered through. wherever heat-resistance was wanted. It would be much easier to manufacture

To return, however, to the Geophysical marble, which is only carbonate of lime. Laboratory, it may be said that, the earth Marble is a limestone rock which has unhaving been originally molten, and grad- dergone metamorphosis under conditions

HUGE ELECTRO-MAGNET FOR TESTING MAGNETISM OF

MAGNETIC IRON ORES.
Its grip has the strength of four locomotives.

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of heat and pressure. These conditions get at the bottom of the puzzle. Oxide could be imitated in the electric furnace, of aluminum sometimes crystallizes as exposing lime at a high temperature to ruby, sometimes as sapphire, and somecarbonic acid gas.

times as plain, unornamental emery. A good deal remains to be ascertained . Why? Nobody can say, but an effort about the effects of steam, under high will be made to ascertain. And, speakpressure," upon ores of the valuable ing of volcanoes, at what temperatures metals. Indeed, one may say that are minerals of various kinds separated nothing is known as yet on the subject. out of the stuff ejected by burning When the desired information has been secured, something at least will have been learned of the secret of the rich deposits which contribite so much to the wealth of this country. The ores of all these metals were at one time dissolved in water. There is copper, for example. Water evidently had much to do with the making of the great copper deposits. But in what way? Nobody can

ONE OF THE LARGEST METEORITES Ever KNOWN say exactly ; it is one of the things that the Geo

Mexico, by Professor Ward, of Rochester, N. Y. physical Laboratory is anxious to determine, if possible.

mountains, so as to cool in the forms of The experts will try to make precious different species of rocks? It is a quesstones—diamonds, rubies, sapphires, em- tion to which as yet no answer can be eralds, and other kinds of gems. Not for given. commercial purposes, however. It is a When the matter comes to be conscientific problem, pure and simple, that sidered, it is really astonishing how they are attacking Microscopic dia- little we know about the way in which the monds have already been produced in the crust of the planet on which we dwell electric furnace by Crookes and De Mois- was formed. We recognize, here and san, and quite recently real rubies have there, various kinds of rocks; but we been crystallized from corundum by simi- have no very definite notion of the way in lar means—worthless, alas! by reason of which they were made. Many useful their poor color and the thinness of the metals we dig out of the earth, but we crystals. But the Geophysical Labora- cannot tell how they got there. In fact, tory has resources of energy and appara- what we know seems to be only a small tus at its command such as nobody else fraction of what there is to be known. has hitherto possessed ; it may yet smash We are only on the edge of acquaintance the gem market to "smithereens” by dis- with the subject necessarily so interestcoveries novel and spectacular.

ing to all mankind, and for its further Diamonds are known to be a volcanic illumination we must look to the scienproduct. So much is certain ; but the tists in Washington who have newly manner of their formation is in dispute. taken up this original and picturesque The Carnegie folks are going to try to 'branch of investigation.

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A contribution from the sky to the crust of our planet. Found at Bacubirito,

New Marvels in Physics

By Ben Winslow

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HAT the average Q.-Why do the inhabitants of cold

student knows cor- climates eat fat? How would you find,
rectly after his first experimentally, the relative quantities of
quarter in the study heat given off when equal weights of sul-
of physics, would phur, phosphorus, and carbon are thor-
make very dry read oughly burned?
ing; but what he
knows incorrectly is A.-An inhabitant of cold climates eats
extremely interest- fat principally because he can't get no
ing. Probably not lean, also because he wants to raise its

more than one stu- temperature. But if equal weights of dent out of twenty, when he passes sulphur, phosphoorus, and carbon are into the preliminary study of physics, burned in his neighborhood, he will give escapes the danger of too little off eating quite so much. The relative knowledge. He gains but a smat- quantities of eat given off will depend tering of the subject; learns a few upon how much sulphur etc. is burnt and primary principles that are new and how near it is burned to him. If I knew strange to him ; and straightway falls into these facts, it would be an easy sum to the belief that his knowledge is equal to find the answer. any occasion. Even before he has fairly entered upon the elementary stages of

Q.-An iceberg floats with one milthe study. he begins to put his new lion tons of ice above the water line; how knowledge to work. To what extent he many tons are below the water line? can go wrong, is shown by the following

A.-The iceberg Aoats on top because specimens of examination answers. These

it is lighter, hence no tons are below the answers were taken from fifty or more

water line. Another reason is that an examination papers written by first year

iceberg cannot exceed one million tons students, on acoustics, light, and heat. Of

in weight; hence if this much is above course, no one paper contained all the

water, none is below. Ice is exceptional blunders; and in fact, many of the papers

to all other bodies except bismuth. All were practically perfect.

other bodies have one thousand and 9.-What are the conditions favorable

ninety feet below the surface and two for the formation of dew?

feet extra for every degree centigrade. If it were not for this, all fish would die,

P. S. When I say one thousand and A.—A body of gas as it ascends, ex

ninety feet, I mean one thousand and pands, cools, and deposits moisture; so if

ninety feet per second. you walk up hill the body of gas inside you expands, gives its heat to you, and Q.How has the velocity of light . deposits its moisture in the form of dew been measured? or common swet. Hense these are the favorable conditions; moreover, it ex A.—An atheistic scientist (falsely soplains why. you get warm by ascending called) tried experiments on the staela hill, in opposition to the well-known lites of Jupiter. He found that he could law of the conservation of energy.

delay the eclipse sixteen minutes by

going to the other side of the earths would be a perfect vacuum. The ball orbit; in fact, he found he could make would then bust, but you would not be the eclipse happen when he liked by sim- aware of the fact on account of the loudply shifting his position. Finding that ness of a sound varying with the density credit was given him for determining the of the place in which it was generated, velocity of light, by this means, he re- and not on that on which it is heard. peated it so often that the calendar began to get seriously wrong and there were 0.Why do water pipes burst in cold riots, and Pope Gregory had to set things weather? right.

A.—People who have not studied Q.How would you disprove, experi- acoustice think that Thor burst the inentally, the assertion that white light pipes, but we know that it is nothing of passing through a piece of colored glass the kind for Proffessor Tyndall has burst acquires color from the glass? What is the mythologies and has tought us that it that really happens?

it is the natural behavior of water (and

bismuth) without which all fish would A.—To disprove the assertion that die and the earth would be in an iron “white light passing through a piece of grip. glass acquires color from the glass," I would ask the gentleman to observe that Q.What is the difference between a the glass has just as much color after the "real" and a "virtualimage? Give a light has gone through as it had before. drawing showing the formation of one of That is what really would happen. each kind.

0.-A hollow india rubber ball full of A.—You see a real image every mornair is suspended on one arm of a balance ing when you shave. You do not see a and weighed in the air. The whole is virtual image at all. The only people then covered by the receiver of an air- who see virtual images are those who pump. Explain what will happen as the are not quite right. Vertual images are air in the receiver is exhausted.

those things which do not exist. I cannot

give you a reliable drawing of a virtual A.—The ball would expand and en image, because I never saw one. tirely fill the vessel, driving out all before it. The balance being of greater density It is interesting to analyze these anthan the rest would be the last to go, but swers of blundering students, and enin the end its inertia would be overcome deavor to discover by what mental proand all would be expelled, and there cess they arrived at their conclusions.

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World's New Treasure-Box

By O. J. Stevenson

NE of the most interesting places. The

nteresting places The little town from which the region in America is the Cobalt mining is named, is not yet two years old, and district in northern Ontario —

yet it contains, besides its transient popinteresting on account of the ulation, some two or three thousand inwonderful richness of its mineral wealth,

habitants, and is, to say the least, unique as well as the peculiarly rapid growth

in its appearance-a city of shacks, huts, of Cobalt and the adjacent mining towns.

and tents mingled in delightful confusion, with here and there a sprinkling of modern houses, theaters, banks, and hotels, to give it an up-to-date appearance, the sign of civilization in the wilderness.

To reach Cobalt, on leaving North Bay, a junction point of the Grand Trunk and Canadian Pacific railroads, on the northern shore of Lake Nipissing. you pass through a hundred miles and more of wilderness, forest, rock, lake, and stream, with nowhere a clearing, and

seldom a human habitation. In the fall

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ONE OF THE ORIGINAL HOUSES AT COBALT.

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