Various

“ How many, of engineers even, can explain where the electricity comes from, or how the mechanical power is converted into electrical energy, or what the magnetism of the iron magnets has to do with it all? Take any one of the dynamo-electric machines of the present date--the Siemens, the Gramme, the Brush, or the Edison machine--of each of these there exist descriptions excellent in their way, and sufficient for men already versed in the technicalities of electric science. ”

“ In the silk districts of Europe, agricultural machinery is very much less employed than with us, and in general every woman who can possibly be spared from other work is a field laborer and valuable as such. So that time taken for raising silk must be deducted from her other productive work and charged to the cost of the silk crop. I think that there can be no doubt that this one fact is quite sufficient to make the question of the cost of caring for the worms really as much in favor of the United States as at first glance it appears to be the other way ”

“ Even supposing the ship to be one of our magnificent ironclads, solid, steady, yielding little to the motion of the water, yet she is under steam, the aim of her guns is altered every moment, some oscillation is unavoidable, and she can only estimate the range of her adversary. ”

“ Let us leave the earth for a few minutes and examine the past history of the moon. We have seen the moon revolve around the earth in an ever-widening orbit, and consequently the moon must, in ancient times, have been nearer the earth than it is now. No doubt the change is slow. There is not much difference between the orbit of the moon a thousand years ago and the orbit in which the moon is now moving. But when we rise to millions of years, the difference becomes very appreciable. Thirty or forty millions of years ago the moon was much closer to the earth than it is at present ”

“ But the lines of force crossing through a circuit are not the same thing as the current of electricity that flows round the circuit. You may take a I loop of wire and put the poles of magnets on each side of it so that the lines of force pass through in great numbers from one face to the other, but if you have them there even for months and years the mere presence of these lines of force will not create an electric current even of the feeblest kind. There must be motion to induce a current of electricity to flow in a wire circuit. ”

“ Friction has nothing to do with the matter. The old-fashioned spark-producing "electrical machine" of our youthful days, in which a glass cylinder or disk was rotated by a handle while a rubber of silk pressed against it, has nothing in common with the dynamo-electric generator, except that in both something turns upon an axis as a grindstone or the barrel of a barrel-organ may do. In the modern "dynamo" we cannot help having friction at the bearings and contact pieces, it is true, but there should be no other friction. ”

“ The state of hibernation is not the direct result of an extreme of heat or cold, but rather is caused by a departure from the optimum. In the snail its normal temperature is about the same as the water, and being a poor heat producer it is not surprising that when the water grows colder the animal is forced to succumb; but it is a remarkable fact that warm-blooded animals like many of the above-mentioned, whose bodies are maintained by internal processes at a high temperature of 26° to 38°, are incapable of resisting the lowering influence of cold. The fall in temperature in some is wonderful ”

“ In this producer a current of heated air is introduced into the heart of a body of kindled fuel, and the gases produced--partly by distillation and partly by imperfect combustion of the fuel--are conveyed to the gas inlet of the cylinder or pump of the engine. As the gas in leaving the producer is hot, it is caused to pass through regenerating apparatus, to which it delivers a large portion of its heat before it reaches the engine, and the air which supplies the producer is made to pass through this regenerating apparatus so as to take up the heat abstracted from the gas. ”

“ Taking all these facts into consideration, I am convinced that that there will be no difficulty in raising cocoons for the same cost in labor in the United States as in Europe, and I am inclined to think that the work can be much more cheaply done.
It is true that the United States is not an especially good market for cocoons; in fact up to this time there has been scarcely any market at all for them; but with the organization of the industry and the introduction of reeling machinery, the market will be at least as good there as elsewhere. ”

“ If we draw nearer, this shore is seen to be entirely covered in places with little snails, that, left by the tide, are forging through the mud to regain the water, and the sunlight striking on them is reflected by the glass-like secretion with which they are covered, producing the curious effect noticed. ”

“ As, however, an understanding of the how and the why of the dynamo-electric machine or generator is the very A B C of electrical engineering, an exposition of the fundamental principles of the mechanical production of electric currents demands an important place in the current science of the day. It will be our endeavor to expound these principles in the plainest terms, while at the same time sacrificing nothing in point of scientific accuracy or of essential detail. ”

“ It must not be overlooked that a gun is a machine which has to perform a certain quantity of work of a certain definite kind, and, like all other machines, must be formed specially for its purpose. The motive power is gunpowder, and the article to be produced is perhaps a hole in an armor-plate, perhaps a breach in a concealed escarp, or perhaps destructive effect on troops. ”

“ When the gun is fired, the strain is transmitted at once, or nearly at once, to the breech coil, and thence more slowly to the outer one. Now, as the duration of the pressure increases, owing to the use of larger charges of slower burning powder, it is evident that the more complete and effective will be the transmission of the strain to the exterior, and, consequently, the further into the body of the gun, starting from the bore, and traveling outward, does it become advantageous to employ the stronger material. ”

“ The amount of work performed by gunpowder, when exploded in a gun, is a subject which has engaged a vast quantity of attention, and some highly ingenious methods of calculating it have been put forward. Owing, however, to the impossibility of ascertaining how fast the combustion of large grains and prisms proceeds, a very considerable amount of experience is required to enable the gunmaker to apply the necessary corrections to these calculations; but, on the whole, it may be said that, with a given charge and weight of shot, the muzzle velocity may now be predicted with some accuracy. ”

“ If a trace of protoxide of iron remains in the solution another cubic centimeter of nitric acid ought to be added and the boiling continued so long as any reddish-yellow vapors are visible, more hydrochloric acid also being added to keep the solution from being dried up. The process is continued in this way until two tests have given no reaction of protoxide of iron, when the solution is diluted with water; but no dilution should take place until the oxidation is complete, because in the course of it the solution ought to be kept as concentrated as possible. ”

“ Specimens which I kept exposed to direct sunshine for days together in a shallow vessel placed on a white slab, soon acquired a dark, unhealthy hue, as if being oxygenated too rapidly, although I protected them from any undue rise of temperature by keeping up a flow of cold water. So, too, I found that Radiolarians were killed by a day's exposure to sunshine, even in cool water, and it is to the need for escaping this too rapid oxidation that I ascribe their remarkable habit of leaving the surface and sinking into deep water early in the day. ”

“ When we compare the formula of water with that of hydrochloric acid, we find that there is twice as much hydrogen combined with one atom of oxygen as there is combined with one atom of chlorine; and in a great many other instances, we find that we can replace two atoms of chlorine by one atom of oxygen, so that we get an idea of the exchangeable value of these elements, and we say that one atom of oxygen is worth two of chlorine, or is bivalent ”

“ Gunpowder is commonly termed an explosive, but this hardly represents its qualities accurately. With a true explosive, such as gun-cotton, nitro glycerine and its compounds, detonation and conversion of the whole into gas are practically instantaneous, whatever the size of the mass; while, with gunpowder, only the exterior of the grain or lump burns and gives off gas, so that the larger the grain the slower the combustion. The products consist of liquids and gases. The gas, when cooled down to ordinary temperature, occupies about 280 times the volume of the powder. ”

“ Would it be true to assert that the finger of the rifleman which pulls the trigger supplies the energy with which the rifle bullet is animated? Of course it would not. The energy is derived from the explosion of gunpowder, and the pulling of the trigger is merely the means by which that energy is liberated. ”

“ But it is frequently overlooked that the victory of a plate is a complete victory. If the shot does not get through, it does practically nothing. On the other hand, the victory of the gun is but a partial triumph; it is confined to a small arc. I mean that, when the plate is struck at an angle exceeding 30° or so, the shot glances harmlessly off; while, even when perforation is obtained, it is at the expense of the more deadly qualities of the projectile, which must be a nearly solid bolt, unable to carry in with it heavy bursting charges of powder or destructive masses of balls. ”

“ Architects would gladly resort to the last-named material if it could be procured in sufficient size and mass without the difficulties attendant upon shrinkage in the burning, and the winding and unevenness of the lines thereby caused. They have also an even more tractable material in concrete ready to their hand, if they would seriously bring themselves to the task of stamping an expressive art upon it, instead of going on designing concrete houses as if they were stone ones. Cast iron has the advantage of being a tried material ”

“ To use a rough comparison, I should esteem it as wasteful, even if possible, for each grower to attempt to reel his own cocoons as for each farmer to grind his own wheat upon his farm and endeavor to sell the flour. ”

“ I may here remark, that the increased length of gun necessary to produce the best effect is causing even those who have possessed breech-loaders for many years to rearm, just as completely as we are now beginning to do. All the old short breech loading guns are becoming obsolete. Another great advantage of breech-loading is the facility afforded for enlarging the powder chamber of the gun, so that a comparatively short, thick cartridge may be I employed, without any definite restriction due to the size of the bore. ”

“ A piece of round section, only one thirty-fifth of an inch in diameter, will just sustain a heavy man.
If, now, a steel tube, suitable for the lining of a gun, be prepared by having wire wound round it very tightly, layer over layer, it will be compressed as the winding proceeds, and the tension of the wire will act as shrinkage. You will readily understand that a gun can be thus formed, having enormous strength to resist bursting. Unfortunately, the wires have no cohesion with one another, and the great difficulty with construction of this kind is to obtain what gun-makers call end strength. ”

“ To be able, then, to reel silk by the ordinary reels, it would first be necessary to find a sufficiency of highly skilled operatives willing to labor in a factory thirteen hours per day for twenty cents each. I sincerely believe and hope that this can never be done. I have enlarged somewhat upon this difficulty for the purpose of showing that the growers, or at any rate individual growers of cocoons, should not attempt to do the reeling, but by no means with an idea of discouraging the raising of silk worms, which is and should be an entirely separate matter. ”

“ Thus, while not exceeding the intended pressure at the breech, the pressure toward the muzzle is kept up, and the velocity very materially increased. Following this principle to this conclusion, it will be found that the perfect charge for a gun will be one which exactly fills the chamber, and which is composed of a powder rather too slow to give the pressure for which the gun is designed, supposing the shot to move off freely. The powder should be so much too slow as to require for its full development the holding power of a band which is just strong enough to give rotation to the shot. ”