Chapter 8

In conclusion, I wish to draw attention to an important discovery I have made in reference to blackened ceilings, for which, up to the present time, gas has been chiefly blamed. I have long entertained the belief that with a proper burner it is possible to obtain perfect combustion, without any smoke; and a series of experiments with white porcelain plates hung over some burners used in my own house proved conclusively that the discoloration which spread itself all over my whitewashed ceilings arose from the state of the atmosphere, which in all large towns is largely mixed with heavy smoky particles, and from the dust or dirt created in rooms by the use of coal fires as well as from the smoke which, more frequently than one is at first supposed to imagine, escapes from the fire-place into the room. I therefore, in two of my best rooms, which required to have the ceilings whitened every year, substituted varnished paper ceilings (light oak paper, simply put on in the usual way, and varnished) instead of whitewash. I also changed the coal fires for gas fires. These alterations have gone through the test of two winters, and the ceilings are now as clean as when they were first done. The burners have been used every night, and the gas fires every day, during the two winters. No alteration has been made in the burners employed, and no "consumers" have been used over them. If the varnished paper ceilings are tried, I am sure that every one will like them better than the time honored dirty whitewash, which is simply a fine sieve. This fact is clearly shown by the appearance of the rafters, which, after a short time, invariably show themselves whiter than the spaces between.

* * * * *

ANDERS' TELEPHONE.

Mr. G.L. Anders' telephone, shown in the accompanying cut, combines in a single apparatus a transmitter, A, a receiver, B, and a pile, C. The transmitter consists of a felt disk, a, containing several large apertures, and fixed by an insulating ring, c, to a metallic disk, d, situated within the box, D. The apertures, b, are filled with powdered carbon, e, and are covered by a thin metal plate, f, which is fixed to the insulating ring, c, by means of a metallic washer, g. Back of the transmitter is arranged the receiver, B, which consists of an ordinary electro-magnet with a disk in front of its poles. The pile, C, placed behind the receiver, consists of a piece of carbon, h, held by a partition, i, and covered with a salt of mercury, and of a plate of zinc, l, which is held at a distance from the mercurial salt by a spring, m, fixed to the insulating piece, n.

When the button, o, which is a poor conductor, is pressed, the zinc plate, l, comes into contact with the mercurial salt, and the circuit is closed through the line wire 1, the pile, the receiver, the transmitter, and the line wire 2, while when the button is freed the current no longer passes. The apparatus, then, can serve as a receiver or transmitter only when the button is pressed.--_Bull. de la Musee de l'Industrie_.

* * * * *

BROWN'S ELECTRIC SPEED REGULATOR.

When the sea is rough, and the screw leaves the water as a consequence of the ship's motions, the rotary velocity of the screw and engine increases to a dangerous degree, because the resistance that the screw was meeting in the water suddenly disappears. When the screw enters the water again, the resistance makes itself abruptly felt, and causes powerful shocks, which put both the screw and engine in danger. Ordinary regulators are powerless to overcome this trouble, since their construction is such that they act upon the engine only when the excess of velocity has already been reached.

Several remedies have been proposed for this danger. For example, use has been made of a float placed in a channel at the side of the screw, and which closes the moderator valve by mechanical means or by electricity when the screw descends too low or rises too high.

Mr. Brown's system is based upon a new idea. The apparatus (see figure) consists of two contacts connected by an electric circuit. One of them, b, is fixed to the ship in such a way as to be constantly in the water, while the other, a, corresponds to the position above which the screw cannot rise without taking on a dangerous velocity. In the normal situation of the ship, the electric circuit, c (in which circulates a current produced by a dynamo, d), is closed through the intermedium of the water, which establishes a connection between the two contacts. When the contact, a, rises out of the water, the current is interrupted. The electro, d, then frees its armature, f, and the latter is pulled back by a spring--a motion that sets in action a small steam engine that closes the moderator valve. When the contact, a, is again immersed, the electro, e, attracts its armature, and thus brings the moderator valve back to its normal position. It is clear that the contact, a, must be insulated from the ship's side.

Several contacts, a, might be advantageously arranged one above another, in order to close the moderator valve more or less, according to the extent of the screw's rise or fall.

* * * * *

MAGNETO-ELECTRIC CROSSING SIGNAL.

We illustrate to-day a new application of electricity to railroad crossing signaling which the Pennsylvania Steel Company, of Steelton, Pa., has just perfected. By its operation an isolated highway crossing in the woods or any lonely place can be made perfectly safe, and that, too, without the expense of gates and a man to work them or of a flagman. It is surely a great improvement over the old methods, and it is likely to have a large sale. In addition to considerations of safety, possible saving in salaries to railroad companies by its use will be great. This device is more reliable than a human being, and can make any crossing safe to which it is applied. Its operation is described as follows:

The illustration shows the device as used on a single track railroad, where it is so arranged as to be operated only by trains approaching the crossing (i.e., in the form illustrated, from the right). A similar box on the other side of the crossing is used for trains approaching in the other direction. Two plates connected by a link, and pivoted, are placed alongside of one rail, close enough to it to be depressed by the treads of the wheels. By another link, one of the plates called the rock plate (the one to the right) is connected to a rock shaft which extends through a strong bearing into the heavy iron case or box shown, at a suitable distance from the rail, within which an electric generator is placed; the whole being mounted and secured upon the ends of two long ties framed to receive it.

The action of this rock plate is peculiar. It is pivoted at the rear end, not to a fixed point, but to a short crank arm, the bearing for which is inclosed in the small box shown. As the first wheel of a train which is approaching in the desired direction (from the right in the engraving) touches it, it will be seen that it must not only depress it, but produce a slight forward motion, causing a corresponding rotary motion in the rock shaft which actuates the apparatus. On the other hand, when a train is approaching from the other direction, or has already passed the crossing, its wheels strike first the curved plate to the left of the illustration, and by means of the peculiar link connections shown, depress the rock plate so as to clear the wheels before the wheels touch it, but the depression is directly vertical, so that it does not give any horizontal motion to it, which would have the effect of actuating the rock shaft. Consequently, trains pass over the apparatus in one direction without having any effect upon it whatever, the different point at which the same force is applied to the rock plate giving the latter an entirely different motion.

The slight rotary motion which is in this way communicated to the rock shaft, when a train is approaching in the right direction, compresses a spring inside the case. As each wheel passes off the rock plate, the reaction of the spring throws it up again to its former position, giving additional speed to the gearing within, which is set in motion at the passage of the first wheel, and operates the electric "generator." The spring is really the motive power of the alarm. A small but heavy fly-wheel is connected with the apparatus, the top of which is just visible in the engraving, which serves to store up power to run the "generator," which is nothing more than a small dynamo, for the necessary number of seconds after the rear of the train has passed. The dynamo dispenses with all need for batteries, and reduces the work of maintenance to occasionally refilling the oil-cups and noticing if any part has been broken.

A suitable wire circuit is provided, commencing at the generator with insulated and protected wire, and continued with ordinary telegraph wire, which can be strung on telegraph poles or trees leading to the electric gong, Fig. 2, which rings as long as the armature revolves. It is a simple matter so to proportion the mechanism for the required distance and speed that the revolutions of the armature and the ringing of the gong shall continue until the train reaches the crossing; and as each wheel acts upon the apparatus, the more wheels there are in the train the longer the bell will ring, a very convenient property, since the slowest trains have nearly always the most wheels. The practical limits to the ringing of the gong are that it will stop sounding after the head of the train has passed the crossing and before or very soon after the rear has passed. A "wild" engine running very slowly might not actuate the signal as long as was desirable, but even then it is not unreasonably claimed the warning would probably last long enough for all practical requirements, as a team approaching a crossing at eight miles per hour takes 42 seconds to go 500 feet. All the bearings of any importance are self-lubricated by oil cups, the whole apparatus being designed to require inspection not more than once a month. The iron case when shut is water-tight, and when duly locked cannot be maliciously tampered with without breaking open the case; so that, the manufacturers claim, it will not be essential to examine it more than once a month. The parts outside the case are all strong and heavy, and not likely to get out of order, while easily inspected.

The apparatus can be used for announcing trains as well as sounding alarms, as the gongs can be placed upon any post or building. The gong has a heavy striker, and makes a great deal of noise, so that no one should fail to hear it.--_Railway Review_.

* * * * *

THE SIZES OF BLOOD CORPUSCLES.

Professor Theodore G. Wormley, in the new edition of his work, gives the following sizes of blood corpuscles, as measured by himself and Professor Gulliver. We have only copied the sizes for mammals and birds. It will be seen that, with three or four exceptions, the sizes obtained by the two observers are practically the same:

Mammals Wormley. Gulliver.

Man 1-3250 1-3260 Monkey 1-3382 1-3412 Opossum 1-3145 1-3557 Guinea pig 1-3223 1-3538 Kangaroo 1-3410 1-3440 Muskrat 1-3282 1-3550 Dog 1-3561 1-3532 Rabbit 1-3653 1-3607 Rat 1-3652 1-3754 Mouse 1-3743 1-3814 Pig 1-4268 1-4230 Ox 1-4219 1-4267 Horse 1-4243 1-4600 Cat 1-4372 1-4404 Elk 1-4384 1-3938 Buffalo 1-4351 1-4586 Wolf (prairie) 1-3422 1-3600 Bear (black) 1-3656 1-3693 Hyena 1-3644 1-3735 Squirrel (red) 1-4140 1-4000 Raccoon 1-4084 1-3950 Elephant 1-2738 1-2745 Leopard 1-4390 1-4319 Hippopotamus 1-3560 1-3429 Rhinoceros 1-3649 1-3765 Tapir 1-4175 1-4000 Lion 1-4143 1-4322 Ocelot 1-3885 1-4220 Mule 1-3760 Ass 1-3620 1-4000 Ground squirrel 1-4200 Bat 1-3966 1-4173 Sheep 1-4912 1-5300 Ibex 1-6445 Goat 1-6189 1-6366 Sloth 1-2865 Platypus (duck-billed) 1-3000 Whale 1-3099 Capybara 1-3164 1-3190 Seal 1-3281 Woodchuck 1-3484 Muskdeer 1-12325 Beaver 1-3325 Porcupine 1-3369 Llama, Long diam. 1-3201 1-3361 Short " 1-6408 1-6229 Camel, Long diam. 1-3331 1-3123 Short " 1-5280 1-5876

WORMLEY GULLIVER. Birds. Length. Breadth. Length. Breadth.

Chicken 1-2080 1-3483 1-2102 1-3466 Turkey 1-1894 1-3444 1-2045 1-3599 Duck 1-1955 1-3504 1-1937 1-3424 Pigeon 1-1892 1-3804 1-1973 1-3643 Goose 1836 1-3839 Quail 2347 1-3470 Dove 2005 1-3369 Sparrow 2140 1-3500 Owl 1736 1-4076

The subject of minute measurements was discussed in an interesting manner in an address before the Microscopical Section of the A.A.A.S. last year, an abstract of which was published in this journal, vol. v., p. 181.

The slight differences in size accurately given in this table are not always appreciable under modern amplification, but under a power of 1,150 diameters "corpuscles differing by the 1-100000 of an inch are readily discriminated." For the conclusions of Prof. Wormley as regards the possibility of identifying blood of different animals, the reader is referred to his book on Micro-Chemistry of Poisons.--_Amer. Micro. Jour._

* * * * *

THE ABSORPTION OF PETROLEUM OINTMENT AND LARD BY THE SKIN.

[Footnote: From the _American Druggist_.]

E. Joerss has investigated the question whether ointments made with vaseline or other petroleum ointments are really as difficult of resorption by the skin, or of yielding their medicinal ingredients to the latter, as has been asserted. In solving this question, he considered himself justified in drawing conclusions from the manner in which such compounds behaved toward _dead_ animal membrane. If any kind of osmosis could take place, he argued, from ointments prepared with vaseline, etc., through dead membranes, such osmosis would most probably also take place through living membranes. At all events, the endosmotic or exosmotic action of the skin of a living body must necessarily play an important _role_ in the absorption of medicinal agents; and, on the other hand, it is plain that fats, which render the living skin impermeable, necessarily also diminish or entirely neutralize its osmotic action. To test this, the author made the following experiments:

Bladder was tied over the necks of three wide-mouthed vials, with bottoms cut off, and each was filled with iodide of potassium ointment.

No. 1 contained an ointment made with lard.

No. 2, one made with unguentum paraffini (_Germ. Pharm_.), and

No. 3, one made with unguentum paraffini mixed with 3 per cent. of lard.

All three vials were then suspended in beakers filled with water. After standing twenty-four hours at the ordinary temperature, the contents of none of the beakers gave any iodine reaction. After having been placed into a warm temperature, between 25-37° C., all three showed iodine reactions after three hours, Nos. 2 and 3 very strongly, No. 1 (with lard alone) very faintly.

The same experiment was now repeated, with the precaution that the bladder was previously washed completely free from chlorine. Each vial was suspended, at a temperature of 25-27° C., in 50 grammes of distilled water. After three hours, the contents of No. 1 (containing the ointment made with _lard_) gave _no_ iodine reaction; the contents of the other two, however, gave traces. After eight hours no further change had taken place. The temperature was now raised to 30-35° C., and kept so for eight hours. All three beakers now gave a strong iodine reaction, 0.2 c.c. of normal silver solution being required for each 15 grammes of the contents of the beakers.

In addition to the iodide, some of the fatty base had osmosed through the membrane in each case.

The next experiment was made by substituting a piece of the skin (freed from chlorine by washing) of a freshly killed sheep for the bladder. The ointment in No. 3 in this case was made with 10 per cent. of lard. No reaction was obtained, at the ordinary temperature, after twelve hours, nor after eight more hours, at a temperature of 25-30° C. After letting them stand for eight hours longer at 30-37° C., a faint reaction was obtained in the case of the ointment made with unguentum paraffini; a still fainter with No. 3; but no reaction at all with No. 1 (that made with lard). None of the fats passed through by osmosis. After eight hours more, the iodine reaction was quite decisive in all cases, but no fat had passed through even now. On titrating 20 grammes of the contents of each beaker,

No. 1 required 0.5 c.c. of silver solution. No. 3 " 0.5 c.c. " No. 2 " 0.7 c.c. "

showing that the most iodine had osmosed in the case of the ointment made with unguentum paraffini (equivalent to vaseline).

* * * * *

THE TAILS OF COMETS.

I.--If we throw a stone into the water, a wave will be produced that will extend in a circle. The size of this wave and the velocity with which it extends depend upon the size of the stone, that is to say, upon the intensity of the mechanical action that created it. The extent and depth of the water are likewise factors.

If we cause a cord to vibrate in the water, we shall obtain a succession of waves, the velocity and size of which will be derived from the cord's size and the intensity of its action. These waves, which are visible upon the surface, constitute what I shall call _mechanical waves_. But there will be created at the same time other waves, whose velocity of propagation will be much greater than that of the mechanical ones, and apparently independent of mechanical intensity. These are _acoustic waves_. Finally, there will doubtless be created _optical waves_, whose velocity will exceed that of the acoustic ones. That is to say, if a person fell into water from a great height, and all his senses were sufficiently acute, he would first perceive a luminous sensation when the first optical wave reached him, then he would perceive the sound produced, and later still he would feel, through a slight tremor, the mechanical wave.[1]

[Footnote 1: Certain persons, as well known, undergo an optical impression under the action of certain sounds.]

Under the action of the same mechanical energy there form, then, in a mass of fluid, waves that vary in nature, intensity, and velocity of propagation; and although but three modes appreciable to our senses have been cited, it does not follow that these are the only ones possible.

We may remark, again, that if we produce a single wave upon water, it will be propagated in a uniform motion, and will form in front of it successive waves whose velocity of propagation is accelerated.

This may explain why sounds perceived at great distances are briefer than at small ones. A detonation that gives a quick dead sound at a few yards is of much longer duration, and softer at a great distance.

The laws that govern the system of wave propagation are, then, very complex.

II.--If an obstacle be in the way of the waves, there will occur in each of them an _alteration_, a break, which it will carry along with it to a greater or less distance. This succession of alterations forms a trace behind the obstacle, and in opposition to the line of the centers. Finally, if the obstacle itself emits waves in space that are of less intensity then those which meet it, these little waves will extend in the wake of the large ones, and will form a trace of parabolic form situated upon the line of the centers.

III.--Let us admit, then, that the sun, through the peculiar energy that develops upon its surface or in its atmosphere, engenders in ethereal space successive waves of varying nature and intensity, as has been said above, and let us admit that its _mechanical_ waves are traversed obliquely (Fig. 1) by any spherical body--by a comet, for example; then, under the excitation of the waves that it is traversing, and through its velocity, the comet will itself enter into action, and produce mechanical waves in its turn. As the trace produced in the solar waves consists of an agitation of the ether on such trace, it will become apparent, if we admit that every luminous effect is produced by an excitation--a setting of the ether in vibration. The mechanical waves engender of themselves, then, an emission of optical waves that render perceptible the alteration which they create in each other.

Let a be the position of the comet. The altered wave, a, will carry along the mark of such alteration in the direction a b, while at the same time extending transversely the waves emitted by the comet. During this time the comet will advance to a', and the wave will be altered in its turn, and carry such alteration in the direction, a' b'.

The succession of all these alterations will be found, then, upon a curve a'' d' d, whose first elements, on coming from the comet, will be upon the resultant of the comet's velocity, and of the propagation of the solar waves. Consequently, the slower the motion of the comet, with respect to the velocity of the solar waves, the closer will such resultant approach the line of centers, and the more rectilinear will appear the trace or tail of the comet.

IV.--If the comet have satellites, we shall see, according to the relative position of these, several tails appear, and these will seem to form at different epochs. If c and s be the positions of a comet and a satellite, it will be seen that if, while the comet is proceeding to c', the satellite, through its revolution around it, goes to s', the traces formed at c and s will be extended to d and d', and that we shall have two tails, c' d and s' d', which will be separated at d and d' and seem to be confounded toward c' s'.

V.--When the comet recedes from the sun, the same effect will occur--the tail will precede it, and will be so much the more in a line with the sun in proportion as the velocity of the solar waves exceeds that of the comet.