Messrs. Müthel & Lütche, of Berlin, recommend the following process for the manufacture of varnish: The oils are treated by gases or gaseous mixtures that have previously been submitted to the action of electric discharges. The strongly oxidized oxygenated compounds that are formed under such circumstances give rise, at a proper elevation of temperature, to compounds less rich in oxygen, and the oxygen that is set free acts upon the fatty acid that it is proposed to treat. A mixture of equal parts of chlorine and steam may be very advantageously employed, as well as anhydrous sulphuric acid and water, or oxygen, anhydrous sulphuric acid and protoxide of nitrogen, nitrogen, oxygen, and hydrogen, protoxide of nitrogen and air, or oxygen, and so on.
The apparatus is shown in section in the accompanying engraving; a is a steam-pipe running from the boiler to the motor. From this pipe branch conduits, b, that enter the vessels, B, in which the treatment is effected, and that run spirally through the oil. At the lower part of the vessel, B, there is tube wound into a flat spiral, and containing a large number of exceedingly small apertures.
The oxidizing apparatus is shown at p. The gaseous mixture enters through the tube, n, traverses the apparatus, p, and enters the vessel, B, through the tubes, g and D. Fig. 2 gives the details of the oxidizing apparatus, which consists of two concentric glass tubes, A and F, soldered at x. A is closed beneath and held in a cylinder, C; F contains a small aperture through which passes a tube, E. The gaseous mixture enters through the latter, traverses the annular space between the tubes, A and F, and then makes its exit through H, whence it goes to a similar apparatus placed alongside of the other. The shaded parts of the engraving represent bodies that are good conductors of electricity and that communicate with the two poles of any electrice source whatever.
FIGS. 1 AND 2.
The operation is as follows: After opening the tube, e, linseed oil is introduced into the vessel, B, until the latter is half full, and, after this, e is closed and the worm, S, is allowed to raise the temperature to between 60° and 80°. Then the cock of the tube, d, which communicates with an air pump, is opened, and the pressure is diminished to about 730 mm. of mercury. At this moment the oxidizing apparatus are put in communication with an induction bobbin that is interposed in the circuit of a dynamo, while through the tube, n, there is made to enter a mixture of equal parts (in volume) of sulphurous acid, oxygen, and air. At the same time, the cock of the tube, g, is opened, while the stirrer, T, is set in motion. In this way we obtain, in a much shorter time than by ordinary processes, a very liquid, transparent varnish, which, when exposed to the air, quickly hardens. It is possible, with the same process, to employ a mixture (in volumes) of two parts of protoxide of nitrogen with one and a half parts of atmospheric air, or even protoxide of nitrogen alone.
When it is judged that the operation is finished, the tube, g, is opened, the stirrer is stopped, and the tube, c, is opened after d has been closed. The steam then forces the varnish to pass through the tube, f, and traverse the washing apparatus, which is filled half full of water, that is slightly ammoniacal, and is heated by a circulation of steam, S. Finally, the product, washed and free from every trace of acid is collected upon making its exit from the tube, h.—La Lumiere Electrique.
We borrow from the Elektrotechnische Zeitung the following details in regard to the telephonic installations made by the Brothers Naglo at Berlin. Fig. 1 gives the general arrangement of a station, where J is an inductor set in motion through a winch, K, and a pair of friction rollers; W, a polarized call; U, an ordinary two-direction commutator; B, a lightning protector; and L and T, the two terminals of the apparatus, one of them connecting with the line and the other with the earth. The interesting point of this system is the automatic communication which occurs when the inductor, J, is moved. At the same moment that the winch, K, is being moved, the disk, P, is carried from right to left and brought into contact with the spring, f2. As soon as the winch is left to itself a counter-spring forces the disk, P, to return to a contact with the spring, f1. Figs. 2 and 3 show the details of such communication. The winch, K, is keyed to one of the extremities of a sleeve that carries the disk, P, at its other extremity. This sleeve is fixed upon the axle of the first friction roller, that is to say, upon the axle that controls the motion of the inductor, and is provided at the center with two helicoidal grooves, e, at right angles with one another. In these grooves slides a tappet, n, connected with the axle.
FIG. 1.
Under the influence of the counter-spring at the left of the disk, P, the latter constantly tends to occupy the position shown in Fig. 2, which is that of rest. As soon as the winch, K, is revolved, whatever be the direction of the motion, the axle can only be carried along when the tappet, n, has come to occupy the position shown in Fig. 3, that is to say, when the disk has moved from right to left a distance corresponding to the fraction of the helix formed in the sleeve.
This stated, it is easy to understand the travel of the currents. Fig. 1 shows the station at rest. The current that arrives through L passes through the lightning protector, the body of the commutator, U, the terminal, v, and the call, W, bifurcates at P, and is closed by the earth. The inductor is in circuit, but, as it is in derivation, upon a very feeble resistance, v, nearly the whole of the current passes through the latter. When it is the station that is calling, the call, W, is put in derivation upon the circuit, f2 p, h, so that the portion of the circuit that passes through q W v is exceedingly feeble, and incapable of operating the bell of the post that is calling.
FIGS. 2 AND 3.
Finally, when the telephone is unhooked, the inductor, J, and the bell, W, are thrown out of circuit, and the telephone is interposed between d and i, that is, between L and T.—La Lumiere Electrique.
In the Gerard incandescent lamp the carbons have the form of a V. They are obtained by agglomerating very finely powdered carbon, and passing it through a draw plate. At their extremity they are cemented together with a small quantity of carbon paste, and their connection with the platinum conducting wires is effected by means of a cylinder of the same paste surmounted by a cone. These couplings secure a good contact, and, by their dimensions, prevent the attachments from becoming hot and consequently injuring the carbon at this point. The cone forms a connection of decreasing section, and prevents the carbon from getting broken during carriage.
This process of manufacture permits of obtaining lamps of all intensities, from 3 candles up. The following, according to Mr. Gerard, are the consumptions of energy in each size of lamp:
It will be seen that these lamps require a relatively intense current with much less fall of potential than the Swan, for example—this being due to the diameter of the filament. But, what is an inconvenience as regards mounting, if we wish to supply them by ordinary machines (for they must be mounted in series of 3 on each derived circuit if the machine gives, as most frequently the case, 100 volts), is an advantage as regards the quality and steadiness of the light and the duration of the lamps.
GERARD'S INCANDESCENT LAMP.
The part in which the energy is expended is homogeneous, as might be supposed from the mode of manufacture, and as may be ascertained from a microscopical examination, and it is exempt from those variations in composition that are found in carbons of a vegetable nature, like the Edison. Besides, being of relatively large diameter, the lamp is capable of supporting a very great increase of temperature.
The process employed for fixing the lamps is as simple as can be. Each platinum wire is soldered to a piece of copper that surrounds the base of the lamp and that is fixed to the glass with a special cement. These two armatures intertwine, but at a sufficient distance apart to prevent contact. They carry a longitudinal projection and an inflation that fit by hard friction into two copper springs connected electrically with the circuit. It is only necessary to lift the lamp in order to remove it from the support; and the contrary operation is just as easy.—Le Genie Civil.
Fig. 1 shows an elevation of the instrument and a horizontal section of the bobbins. Two pairs of bobbins, cc, cc, are so arranged that the axes of each pair are parallel and in the same vertical plane. Each pair is supported by a vertical brass plate, and the two plates make an angle of about 106° with each other, so that the planes containing the axes of the bobbins make an angle of about 74°. Two horseshoe magnets, m m, made of 1/25 inch steel wire, are connected by a very light piece of aluminum and placed at such a distance from each other that, on being suspended, the two branches of each of the magnets shall freely enter the respective bores of the two bobbins fixed upon the same plate, and, when the whole system is in equilibrium and the bobbins free from current, the two branches of each of the magnets shall nearly coincide with the axes of such bores. The magnets are not plane, but are curved so as to form portions of a vertical cylinder whose axis coincides with the direction of the suspension wire, and to which the axes of the bobbins are tangent at their center, approximately to the points where the poles of the magnets are situated.
FIG. 1. GRAY'S GALVANOMETER.
The needles have been given this form so that their extremities shall not touch the sides of the bore during considerable deflections.
In the instrument which the inventors, Messrs. T. & A. Gray, used in their experiments upon the resistance of glass, the needles were arranged so that their poles of contrary name were opposite.
FIG. 2.
The system of needles is suspended from the extremity of a screw, p, which passes into a nut, n, movable between two stationary pieces. On revolving the nut, we cause the screw to rise or lower, along with the entire suspended part, without twisting the thread.
The four bobbins are grouped for tension, and have a total resistance of 30,220 ohms. They contain 16,000 feet of No. 50 copper wire, forming 62,939 revolutions, nearly equally divided between the four bobbins. When a current is passing through the bobbins, the poles of one of the horseshoe magnets are attracted toward the interior of the corresponding bobbins, while those of the other are repelled toward the exterior by the two other bobbins. We thus have a couple which tends to cause the system to revolve around the suspension axis. A mirror, which is fixed upon a vertical piece of aluminum, a, gives, in the usual manner, a reflected image upon a scale, thus allowing the deflections to be read. A compensating magnet, M, is supported by a vertical column fixed to the case, above the needles. This magnet may be placed in the different azimuths by means of a tangential screw, t. The extremities of the bobbin wires are connected with three terminals, T, T1, T2, and the instrument may, by a proper arrangement, became differential. These terminals, as well as the communicating wires, are insulated with ebonite.
Thus arranged, the instrument is capable of making a deflection of one division of 1/50 inch upon a scale placed at a distance of a little more than a yard, with the current produced by one daniell of 10 ohms. This is a degree of sensitiveness that cannot be obtained with any of the astatic instruments known up to the present. By regulating the needles properly, a greater degree of sensitiveness may be attained, but then the duration of the needles' oscillation becomes too great. The sensitiveness of the instrument is sufficiently great to allow it to be used in many cases, even with a moderate duration of oscillation.
In their experiments upon the resistance of glass, the inventors employed an instrument that was not arranged for giving great sensitiveness, and one with which resistances of from 104 to 105 megohms could be measured by the use of a pile of 120 daniells.
The instrument can be given another form. The four bobbins may be arranged symmetrically in the same plane, and the two horseshoe magnets be supported by an S-shaped aluminum bar. The latter traverses the plate that supports the bobbins, in such a way that one of the magnets enters one of the bobbins that correspond to it on one side of the plate, and the other on the other side, as shown in Fig. 2. The bobbins are so connected that, when they are traversed by a current, both magnets are at the same time attracted toward the interior or repelled toward the exterior of the bobbins. Such a form of the instrument has the advantage of being more easily constructed, while the regulation of the magnets with respect to the bore of the bobbins is easier.
The chief advantage of the instrument results from the fact that, owing to the arrangement of the magnets and bobbins, a large portion of the wires of the latter is situated very near the poles of the magnets, and in a position very favorable for electro-magnetic action. The instrument presents no difficulties as regards construction, and costs no more than an ordinary one.
We might even arrange a single horseshoe magnet, or an S-shaped one, horizontally, and employ but a single pair of bobbins, and thus have a non-astatic apparatus based upon the same principle. But in astatic instruments it is better to place the magnets in such a way that the two branches shall be in the same vertical plane.
Were the line that joins the two poles vertical, the system would be perfectly astatic in a uniform field, since each magnet in particular would then be perfectly astatic. A pair of horseshoe magnets may thus be regulated in such a way as to form a perfectly astatic system in a uniform field and to preserve an almost invariable zero, this being something that it is very difficult to obtain with the ordinary arrangement of needles, especially when a compensating magnet is used; for, in such a case, one of the needles becomes more or less magnetized, while the other becomes demagnetized, according to the position of the compensating magnet.—La Lumiere Electrique.
A cat, dog, rabbit, or Guinea pig will furnish parts from which sections can be cut for the study of histology. Whichever animal is selected should be young and well developed. Put it under influence of chloroform, and open into the cavity of the chest; make an incision into the right ventricle, and allow the animal to bleed to death; cut the trachea and inject the lungs with a solution of one and a half drachms of chromic acid in one quart of water, care being taken not to overdistend the lung. Tie the severed end to prevent the escape of the fluid, and carefully remove the lung. It is a difficult thing to do this without rupturing it, but with care and patience it can be done. Place the lungs in a solution of the same strength as used for injecting; after fifteen or twenty hours change it to a fresh solution, and allow it to remain for about a month, and then change it to rectified spirits, in which it may remain until required.
Cut the tongue into several transverse and longitudinal pieces, also the small intestines, and put them into a solution of fifteen and one-half grains chromic acid, thirty grammes bichromate of potash, and three pints of water; change the solution the next day, and let them remain two weeks and then place in spirits. Cut longitudinal and transverse portions of the stomach and large intestines, wash in a weak solution of salt and water, and put them in the same solution as used for the lungs, and treat similarly.
Cut the kidneys longitudinally and transversely, and put them in a solution of six and one-half drachms bichromate of potash, two and one-half drachms sodium sulphate, one quart of water; change the solution the next day, and at the end of four weeks transfer to alcohol. Wash the inner surface of the bladder with salt and water, and after cutting it longitudinally and transversely, put the sections in a solution of three drachms bichromate of potash in a quart of water. Cut the liver into small parts, and place in the same solution as used for the kidneys; change the solution after a day, and let them remain four or five weeks, then change to spirits. The spleen and portions of the thin abdominal muscles may be placed in a solution of three drachms chromic acid to one quart of water, and transferred to alcohol after three or four weeks. Carefully remove an eye and divide it behind the crystalline lens, put the posterior portion in a solution made by dissolving fifteen grs. chromic acid in five drachms water, and slowly adding five and one-half ounces alcohol; change to spirits in two weeks. The lens should be put in the same solution, but should remain a few days longer. Open the head, remove the brain, and place transverse and longitudinal sections of it in spirits for eighteen hours, then transfer to a solution of one drachm chromic acid in a quart of water, and let it remain until hard enough to cut. Place the uterus in a solution of one and one-half drachms chromic acid in one quart of water, change to a new solution the next day, and at the end of a month transfer to alcohol.
The bones from one of the legs should be carefully cleaned of its muscles, cut into several pieces, and placed in a solution of fifteen and one-half grains chromic acid, one-half drachm nitric acid, and six ounces water. Change the fluid frequently until the bones are sufficiently softened, and then change to alcohol.
Section cutting machines for cutting sections can be procured of the dealers, but a very simple and effective one can be easily made if one does not wish to go to the expense of buying an instrument.
A strip of wood twelve or fourteen inches long and about two inches wide has attached to its center a bridge-shaped piece of wood, a, Fig. 1. This is covered with a brass plate, c, pierced with a hole one-half of an inch in diameter. This hole extends through the wood, and is fitted with a piston. Two long narrow inclined planes of nearly equal inclination, b, b, grooved to slide on each other, are placed under the bridge; the lower is to be fastened to the board; the end of the piston rests on the upper one. The object from which we desire to cut a section is placed in the hole, in the piston. If the upper plane be pushed in, the piston will be forced upward, and with it the object. As the inclination of the plane is very gradual, the vertical motion will be very slight as compared with the horizontal.
When the object is raised a little above the brass plate, a keen edged razor, thoroughly wet, is pushed over the hole, cutting the object. This gives the section a smooth surface, and even with the plate; now push the plane forward one-eighth to one-quarter of an inch, and cut again; this will give a thin section of the object. The thickness of the section depends, of course, on the distance the wedge is pushed.
With a little practice, much better sections can be cut by the hand than by any machine; this does not apply of course to large sections. A razor of good steel, with a blade thin and hard, are the most essential points in an instrument for hand cutting. For ordinary purposes it is not necessary to have the blade ground flat on one side, although many prefer it. The knife should always be thoroughly wet, in order that the cut tissue may float over its surface. Water, alcohol or salt and water may be used for this purpose.
FIG. 1.
To out a section by hand, hold the object between the thumb and first two fingers of the left hand, supporting the back of the knife by the forefinger. The knife is to be held firmly in the right hand, and in cutting should never be pushed, but drawn from heel to point obliquely through the tissue. The section should be removed from the knife by a camel's hair brush.
When the object is too small to hold, it is usually embedded in some convenient substance. A carrot is sometimes very useful for this purpose. A hole rather smaller than the object is cut out of the middle. Put whatever is to be cut into this, and cut a thin section of the whole. The carrot does not cling to either the knife or the section, and the knife is wetted at every slice by it.
Paraffin is the agent usually employed for embedding purposes. Melt it, and add a little lard to soften it; the addition of a little clove oil renders it less adhesive.
Melt the paraffin at as low a temperature as possible, and pour it into a paper cone. Dip the object into this and remove immediately; as soon as the layer of paraffin surrounding it becomes hardened, replace it in the paraffin; this prevents overheating the tissues.
Where the tissues are too soft to be cut, they may be soaked in a solution of gum arabic and dried; in this condition they can be readily cut, after which the gum can be dissolved off. This is an extremely useful method for cutting the lung or other organs where an interstitial support is needed. For a very thin object, a cork fitting any kind of a tube is to be split, and the object placed between the two parts; the cork is then thrust into the tube, and a sufficient degree of firmness will be obtained to allow cutting. The sections should always be manipulated with camel's hair brushes.
Much practice will be required before dexterity is attained.
Methods of preserving the tissues.—All water must be removed from the tissue, either by drying or by immersing it in rectified spirits, and then in absolute alcohol, and the alcohol driven off by floating it upon oil of clove or turpentine. The substances used to preserve the tissues are Canada balsam, Dammar balsam, glycerine, Farrant's solution, potassium acetate, spirits, naphtha, and creosote.
The section is to be floated on to the slide or placed in position with a camel's hair brush. It should be spread out, and then examined under the microscope for the purpose of improving its position if necessary, or of removing any foreign particles. A drop of the preserving medium is then placed upon it, and another placed on the cover and allowed to spread out. The cover is then taken by a pair of pincers and inverted over the object, and one edge brought to touch the slide at one part of its margin. The cover is then gently lowered, and the whole space beneath the cover filled and the tissue completely saturated. If air bubbles show themselves, raise the cover at one corner and deposit a further quantity of the medium.
The slide should be set aside for a few days. First, the excess of the medium must be removed; if it is glycerine, much of it can be removed by a piece of blotting paper, but the cover must not be touched, for it is easily displaced; that near the cover can be replaced by a camel's hair brush. A narrow ring of glycerine jelly should be placed around the edge of the cover, to fix it before the cement is applied. When this has set, a narrow strip of cement is to be put on, just slightly overlapping the edge of the cover and outside the margin of the jelly. Until it has been perfectly secured, a slide carrying glycerine must never be placed in an inclined position, as its cover will slide off.
Preservative media.—Canada balsam may be prepared as follows: Place some pure Canada balsam in a saucer, and cover with paper to exclude dust; dry it in an oven at a temperature of 150°; when it cools, it will become hard and crystalline. Dissolve this in benzole, and use in the same way as glycerine.
Dammar is now used as a substitute for Canada balsam. By its use the tissues are rendered more transparent. To prepare it, dissolve one-half ounce of Dammar rosin and one-half ounce of gum mastic in three ounces of benzole, and filter. This may be used to mount unsoftened bone and tooth, hair, brain, and spinal column, and most tissues that have been hardened in alcohol or chromic acid, which require to have their transparency increased.
Glycerine is not adapted for white fibrous tissue or blood vessels, unless they have been hardened in chromic acid, as it causes the white fibers to swell up and lose their normal features. Sections of liver, lung, skin, and alimentary canal show better in glycerine unless they have been stained.
Farrant's solution may be substituted for glycerine in many instances, because of its feebler tendency to render the tissues transparent. It consists of equal parts of gum arabic, glycerine, and a saturated solution of arsenious acid. In mounting preparations with this medium, the covered object should be allowed to lie a day before the varnish is applied, so that the cover may be fixed, and thereby prevented from being displaced. Rectified spirits may be used for mounting softened bone and tooth, and naphtha and creosote are useful for preserving urinary casts.
When the section is mounted in Canada or Dammar balsam, no cement is required, but for all other preservative media the margin of the cover must be covered with cement. To do this, dry the edges of the cover thoroughly with bibulous paper, and paint a layer of gold size, allowing it to overlap the cover an eighth or sixteenth of an inch, then cover this with white zinc cement.
Preparation for mounting the different tissues.—To obtain a section of bone or tooth requires a grinding down of the tissue until it is so thin as to be transparent. A section should first be cut as thin as possible by a fine saw. It should be attached by the flattest side to a piece of glass, and then ground down by a grindstone or by very fine emery, on a perfectly flat piece of lead. When sufficiently thin and transparent, mount in rectified spirits or Dammar. Sections of the tongue may be made by embedding in paraffin, and mounted in Farrant's solution or glycerine.
Sections of the stomach may also be made by embedding in paraffin, but better ones can be made by freezing. Farrant's solution makes a good mounting.
The intestines also give a better section from freezing than by embedding, as the paraffin injures the villi; mount in the same medium as the stomach.
The liver may be embedded in paraffin, and the section mounted in Farrant's solution or glycerine. The kidney may be treated in the same way. The cornea of the eye can be readily cut by embedding in paraffin, and the section may be mounted in Farrant's solution. The crystalline lens and retina may be treated similarly.
The brain and spinal cord should be embedded in paraffin or a carrot, and the section mounted in Dammar. Sections of the uterus and ovaries are best mounted in glycerine or Dammar. Sections of lung maybe made by embedding in gum or by freezing, and mounted in Farrant's solution.
Every slide should be of uniform size, and labeled. The usual size is 3×1 inches, and should be of a good quality of glass, free from scratches or air holes. They may be labeled either by writing with a diamond, or a small piece of paper affixed to one end, on which is written what is required.
At a recent meeting in London, of the Royal Miscroscopical Society, Dr. Dallinger gave his annual address to what was probably the largest gathering of Fellows ever assembled on a similar occasion. After briefly referring to the increased interest lately manifested in the study of minute organisms, and recalling the characteristics of the doctrines of abiogenesis and biogenesis, he passed rapidly in review the results of the observations of Tyndall, Huxley, and Pasteur as bearing upon these questions, and called attention to the observations of Buchner as to the transformation of Bacillus anthracis and Bacillus subtilis, and vice versa, and referred with approval to Dr. Klein's criticisms thereon. Having spoken of the desirability of careful and continuous study of this class of organisms, and the importance of endeavoring to establish the relation of the pathogenic form to the whole group, he said he should be better able to deal with the subject by recording a few ascertained facts rather than by making a more extended review, and he therefore devoted the main part of his address to a description of "the life history of a septic organism hitherto unknown to science." In his observations of this form—extending over four years—he had the advantage of the highest quality of homogeneous lenses obtainable, ranging from one-tenth to one-fiftieth of an inch, his chief reliance being placed upon a very perfect one thirty-fifth of an inch; and from the continuous nature of the observations as well as the circumstances under which they were carried on, dry lenses had for the most part to be employed. Having in his possession a maceration of cod-fish in a fluid obtained from boiled rabbits, he found at the bottom of it, when in an almost exhausted condition, a precipitate forming a slightly viscid mass, to which his attention was particularly directed. It was seen to contain a vast number of Bacterium termo, but on examination with a one-tenth inch objective showed that it also contained a comparatively small number of intensely active organisms—one being discovered in about eight or ten drops of the sediment. These measured 1-10,000 of an inch in length by 1-19,500 of an inch in breadth. The fluid had originally been kept at a temperature of 90° to 95° F., and it was noticed that, when placed upon a cold stage under the microscope, the movements of the organisms became, gradually slower, until at last they entirely ceased; the necessity, therefore, arose for the use of a warm stage, and the very ingenious contrivance by which a continuous and even temperature was maintained within the one-tenth of a degree was exhibited. The greatest difficulty in the matter was, however, experienced in obtaining specimens for observation, in order to be able to trace them from their earliest to their latest stage. The President then explained, by means of an admirable series of illustrations projected upon a screen by the oxyhydrogen lantern, the life history of the organism to which he had referred, exhibiting it first as a translucent, elliptic, spindle-shaped body, with six long and delicate flagella, the various positions in which the five specimens were drawn giving a very good idea of its peculiar porpoiselike movements.
The various positions which it assumed in making an attack upon a portion of decomposed matter were also shown, the movements quite fascinating the observer by their rhythmical character. The supposed action of the flagella in the production of the movements observed was explained, distinct evidence being afforded of a remarkable spiral motion, at least of those behind. The process of fission was illustrated in all its observed stages from the first appearance of a construction to that of final and complete separation, the whole being performed within the space of eight or nine minutes. A description of the process of fusion from the simple contact of two organisms to their entire absorption into each other followed, as well as their transformation into a granular mass, which gradually decreased in size in consequence of the dropping of a train of granules in it wake as it moved across the field. The development of these granules was traced from their minute semi-opaque and spherical form to that of the perfect flagellate organism first shown, the entire process being completed in about an hour. Experiments as to their thermal death-point showed that, while the adults could not be killed by a temperature less than 146° F., the highest point endured by the germs was 190° F. Illustrations of a variety of other modes of fission discovered in previous researches on similar forms were given, showing the mode of multiple division and a similar process in the case of an organism contained in an investing envelope. The President concluded his address, which was listened to throughout with the greatest attention, by remarking that, though the processes could be seen and their progress traced, the modus operandi was not traceable. Yet the observer could not fail to be impressed with the perfect concurrent adaptation of these organisms to the circumstances of their being; they were subject to no caprices, their life-cycles were as perfect as those of a crustacean or a bird, and while the action of the various processes was certain, their rapidity of increase and the shortness of their life history were such that they afforded a splendid opportunity of testing the correctness of the Darwinian law.
For a number of years previous to 1878 we had in Pembroke but little or no severe cold, owing to the prevalence of southeast, south, west, and especially southwest winds. In many places, fuchsias that were left in the ground for the entire year had not been frozen to the root within the memory of man. Some of these plants had grown to be trees five or six yards in height, and with a trunk the size of one's leg. Now, during the same series of years, many insects that are common throughout the rest of Great Britain did not cease to be rare with us, or rather were confined to certain circumscribed limits. Thus, the Noctuellæ, with the exception of a few species abundant everywhere, were almost wanting, and I know of no other country where the dearth of common species of nocturnal butterflies was so great. But during the winter of 1878 there supervened a radical change. Persistent winds from the northwest, driving back the currents of warm air from the south, brought on an intense cold that froze everything; or, when some variation occurred in them, clouds formed and dissolved into a rain that immediately froze, so that the large roads remained for weeks covered with a layer of rime from two to four inches thick.
GREEN WOODPECKER SEARCHING FOR INSECTS.
GREEN WOODPECKER SEARCHING FOR INSECTS.
The winters of 1879 and 1880 were equally cold; we may even say that the latter was the severest that had been experienced in fifty years. This year the sea-sand, along with the ice and snow, formed a thick crust all along the tide-line—this being something rarely seen along our coast. The first of these three winters (1878-1879) killed all the arborescent veronicas and a few sumacs. As for the fuchsias and myrtles, they were frozen down to the level of the soil.
I now come to the effects of this severe cold upon the insects.
The Lepidoptera, which before were rare, became more and more common in 1879, 1880, and 1881, and so much so that during the last named year they abounded; and species that had formerly been detected only at certain favored points spread over the entire coast and into the interior of the country. The geometers appeared in numbers that were unheard of. But this change was especially striking as regards the Noctuellæ, in view of the previous rarity of the individuals belonging to this family.
We have here an example of the direct relation of cause to effect, although I am not in a position to assert that the effect is always produced in the same way. To me there is no question as to the fact that the constitution of those insects which nature has accorded the faculty of liberating is strengthened, and that their chances of life are increased, if the cold of winter is intense enough to plunge them into an absolute rest, and is not unseasonably affected by warm, spring-like days. It is certain that such cold is capable of contributing largely to the multiplication of the individuals of such species as hibernate in the egg state, and it also has a beneficent influence upon those species which, like the small social larvæ, pass this season upon the earth enveloped in a silken envelope, or, like the larvæ of the Noctuellæ, between dead leaves or upon the ground itself.
On another hand, it cannot be doubted that mild winters greatly contribute to the bringing about of a destruction of larvæ and chrysalids in two ways: First, they favor the development of mould, which, as well known, attacks the larvæ of insects when these have been enfeebled by an excess of rain or dampness; and second, they permit beasts of prey to continue to exercise their activity. Now, these latter are numerous. Moles, instead of burying themselves deeply, then continue to excavate near the surface, and shrew mice are constantly in search of food. These small mammals, which abound in this district, destroy a large number of chrysalids of Lepidoptera.
It is the same with birds. As soon as severe cold begins to prevail in the north and east, they come in troops to the open fields and the sheltered slope of the hills of our district. But it is scarcely worth while to stop to tell of the skill and perseverance of these destroyer of larvæ. We may mention, the woodpecker, however, as a skillful searcher for insects that lie hidden in places where the sun has melted the snow. The carnivorous Coleoptera and the Forficulæ are likewise generally in motion during mild winters. Doubtless these last-named do not make very large inroads in the ranks of larvæ and chrysalids every day; yet, having no other food, they destroy a goodly number of them. But I believe that the devastations made in the army of insects by all these enemies united do not equal those made by certain crustaceans—the wood lice.
During mild winters these pests multiply, eat, and prosper out of bounds, and to such a point that, in a climate like ours, they become a true scourge that prevails everywhere, out of doors and within. Once in a place, they begin to look for larvæ and chrysalids, which they devour. The severe cold seems to have destroyed a certain number of them, since they are now not so numerous by far; and it has at least certainly put a stop to their devastations at an epoch when the larvæ are more particularly exposed to the attacks of their enemies. It is to this cause, as well as to the preceding, that I am led to attribute the extraordinary multiplication of so many species during the three last summers, which were separated by severe winters. Last winter was mild, and there is therefore no reason to expect that there will be another multiplication; but I hope that the harm done by such a season will be slight. It is the progressive multiplication of the destroyers, joined to the correlative disappearance of the victims caused by a series of temperate seasons, that is to be feared.
In support of the proposition that I maintain, I may mention still another fact. While this district (Pembroke, Wales) is relatively poor in species whose larvæ feed and hibernate in the open air a few species of Noctuellæ, whose larvæ live buried in the earth, are always abundant. The country is relatively rich in spices of Tortrix, which develop and hibernate in the stalks or roots of plants. It is also worthy of remark that very few of our species seem to be incapable of enduring a severe winter.—C.G. Barret, in Science et Nature.
Prof. C.V. Riley, entomologist, announces that the Department of Agriculture, Washington, will purchase during the coming summer such quantities of silk worm eggs as may be deemed necessary for the distribution that it is proposed to make for the season of 1886. So far as found practicable, the eggs will be purchased of American producers. There are certain precautions, however, that must be taken to insure purchase. Eggs of improved races only (preferably of the French or Italian Yellow Races) will be bought, and the producer should send one or two samples of pierced cocoons with the eggs. In addition to this the producer must conform to certain rules to be hereafter explained, so that an examination may be made that will serve to show the degree of purity of the eggs. No silk culturist should use his crop for the production of eggs unless the worms have shown, until they began the spinning of their cocoons, every sign of perfect, robust health. Any indication of the disease called flacherie, from which the worms so often die after the fourth moult and turn black from putrefaction, or of any other disease from which silk worms suffer, should be considered as ample reason for not using the cocoons for the purpose in question. They should, on the other hand, be sold for the filature. If the worms have all the indications of health until the spinning period, then the cocoons may be used for the production of eggs. The following brief instructions will prove of service to those who which to secure sound eggs:
For each ounce of eggs to be produced, about three-quarters of a pound of fresh cocoons from the finest and firmest in the lot should be chosen. These should be strung in sets upon a thread, care being taken not to pierce the chrysalis, and the strings hung in a cool, darkened room. The moths generally emerge from the cocoons early in the morning, and will be seen crawling about over these, the males being noticeable by their smaller abdomens, more robust antennæ, and by their greater activity. The moths should be placed, regardless of sex, on a table, where they will soon find their mates and couple. As soon as formed, the couples should be removed to another table, that they may not be disturbed by the flutterings of the single moths.
There should be prepared for each ounce of eggs to be produced, about one hundred small bags of fine muslin, made in the following manner: Cut the cloth in pieces 3×6 inches. Then fold one end over so as to leave a single edge of about three-quarters of an inch, as shown in the accompanying cut. This should be sewn up into a bag with the upper end open, and then turned inside out, so that the seams will cause the sides to bulge. Thus completed they are called "cells." The cells should be strung on a cord stretched across the room.
The moths couple as a rule about eight o'clock in the morning. About four in the afternoon they should be separated by taking them by the wings and drawing them gently apart. Each female should now be placed by herself in a cell, which is then closed by a pin as shown in the figure. Here she will lay her eggs and in due time die. The males may as a rule be thrown away, but it is wise to keep a few of the more active ones, in case there should be a superabundance of females the following day.
When the females have finished laying their eggs, which operation occupies about thirty-six hours, they are ready to be shipped to this office. The cells, with their inclosed moths and eggs, should be placed in a strong box of wood or tin, being packed in such a manner that they will not be crushed, and mailed to the entomologist at the department. By using the inclosed return penalty slip, payment of postage may be avoided. The name of the sender should be placed in each box. The moths, as soon as received, will be examined microscopically, and the eggs of those which are found to be free from disease will be weighed and paid for at the rate of $2.50 per ounce of 25 grammes (about 6-7 of an ounce avoirdupois). Silk culturists are advised not to attempt the production of eggs unless they are adepts at the industry, and have had at least one season's experience. We would advise each person desiring to sell, to send a sample first, with a statement of the quantity offered.
Dr. Zintgraff of Bonn has taken a phonograph with him to Africa. He intends to bring home phonograms of the savage dialects which he will hire the natives to speak into the machine.
In Nature for March 5 (p. 408) Prof. Mayer suggests an improvement in our method of determining the mean density of the earth, from which it appears that our plan has not been properly understood. This misunderstanding, no doubt, has arisen from the incomplete description of our method given in the Nature (Jan. 15. p. 260) report of the Proceedings of the Berlin Physical Society, which report was probably the only source of information accessible to Prof. Mayer. We are led therefore to give a short description of our method.
Let H I K L represent a section of a cubical block of lead, about two meters in the edge, and weighing 100,000 kilos. The balance, A B C, is placed in the middle of the upper horizontal surface. It bears the scale-pans, D and E. Under these scale-pans the block is bored vertically through, and two other scale-pans, F and G, are suspended below the block, attached to the balance by means of rods passing through these openings.
A weight D is brought into equilibrium by weights in G. The weight in D is acted upon by the earth's attraction + that of the block, and that in G by the earth's attraction - that of the block. The weights in G are then greater than that in D by twice the attraction of the block. The weight in D in now removed to F, and counterbalanced by weights in E. The weight in E will be less than that in F by twice the attraction of the block. The difference of the two weighings gives therefore four times the attraction of the block. A correction must be introduced for the variation in the earth's attraction due to the different heights of D, E and F, G.
In order to obtain as great a deflection of the balance by the method suggested by Prof. Mayer, each of the mercury spheres must exert the same attraction as our lead block. This would require spheres having radii of about one meter. The length of the beam of the balance would be necessarily at least two meters. Besides, each mass of mercury, would exert some attraction on the weight on the other side, and thus lessen the deviation of the balance.
The method given by Prof. Mayer, except for the suggested employment of mercury, is then no improvement on ours. If we should use mercury, we would construct a cubical vessel to contain it, and use it as we propose to use the lead block. The advantage of using mercury is, however, counterbalanced by the difficulty of obtaining it in such large quantities as would be necessary.
ARTHUR KONIG.
FRANZ RICHARZ.
Berlin, Physical Institute of the University, March 15.
The Porosity and Permeability of Bodies.—Take two tumblers of the same size, place one of them upon a table, and pour into it a small quantity of nearly boiling water. Cover this glass with a sheet of cardboard, and invert the other one upon it. This second tumbler must be previously wiped so as to have it perfectly dry and transparent. In a few seconds the steam from the lower tumbler will traverse the cardboard (which will thus exhibit its permeability), and will gradually fill the upper tumbler, and condense and run down its sides. Wood and cloth may be experimented with in succession, and will give the same results; but there are other substances that are impermeable, and will not allow themselves to be traversed. Such, for example, is the vulcanized rubber of which waterproofs are made. This experiment explains to us why fog is, as has been well said, so penetrating. It traverses the tissue of our overcoat and of our flannel, and comes into contact with our body. On the contrary, a rubber coat preserves us against its action.
Fig. 1.—EXPERIMENT UPON THE PERMEABILITY OF BODIES.
Fig. 1.—EXPERIMENT UPON THE PERMEABILITY OF BODIES.
A Hot Air Balloon.—Make a hollow cylinder of small diameter out of a sheet of paper such as is used for cigarette packages, and turn in the ends slightly so that it shall preserve its form. If the cylinder seems too difficult to make, a cone may be substituted. Now set fire to the cylinder or cone at its upper part. The paper will burn and become converted into a thin sheet of ashes, which will contract and curl inward. This light residuum of ashes, being filled with air rarefied by combustion, will suddenly rise to a distance of two or three yards. Here we have a Montgolfier balloon.—La Nature.
Fig. 2.—PRINCIPLE OF THE HOT AIR BALLOON.
Fig. 2.—PRINCIPLE OF THE HOT AIR BALLOON.
The little city is situated about half way between Nizza and Mentone, and it formerly was the chief city of a principality that belonged to the family Grimaldi. Prince Florestan sold in 1860 his royal prerogatives to the Emperor Napoleon, for three million francs, consequently the land came under the jurisdiction of the French republic, but the city remained in the Prince's possession, who, however, gave to the gambler Blanc the privilege of erecting a gambling house upon the rocky shore of the sea.
THE CASINO AT MONTE CARLO.
Enormous sums of money were spent to give this isolated cliff its present appearance, covered as it is with beautiful buildings, hotels, and villas, besides the magnificent Casino building, which was erected in 1862. Directly facing the sea, there is a succession of most beautiful gardens and terraces.
But this establishment, which seems like paradise, has had a most disastrous effect upon thousands of persons, and for a long time the subject of influencing the French government to put a stop to this gambling house has been agitated. It can scarcely be imagined how much misery it has already caused. It is evident to every one that the keeper of the bank makes considerable profit, as the chances are 63 times greater in his favor than those of the player.
It is admitted that the profits amount every year to 17 million francs. One can well imagine how many fortunes have been consumed every year to make this profit; but the number cannot be determined.
It is a somewhat unpromising morning—the river is dark with fog and the huge arch of the station nearly hidden by mist and steam. A cold, damp wind makes the passengers hurry into the carriages, and strikes us sharply as we step on to the foot-plate of the engine, which has just joined the train. But as we get behind the shelter of the screen, we feel a generous and slightly unctuous sensation of warmth very comforting to a chilly man. The brasswork of the engine shines brilliantly, the footboard has been newly scrubbed, and the driver and stoker stand waiting for the signal. The needle shows that the steam is just below the pressure at which it would begin to blow off; the water in the gauge glass is just where it ought to be; in fact, the engine is in perfect condition and ready for a start. The line is clear, the guard's whistle is answered by our own, and we glide almost imperceptibly past the last few yards of the platform. The driver opens the regulator till he is answered by a few sounding puffs from the funnel, and then stands on the lookout for signals so numerous that one wonders how he can tell which of the many waving arms is raised or lowered for his guidance.
So he goes on, with hand on regulator and lever, gradually admitting more steam as signal after signal comes nearer and then flies past us, till at last we are clear of the suburbs and find ourselves on a gentle incline and a straight road, with the open fields on either side. It is now that the real business of the journey begins. Locomotives are as sensitive and have as many peculiarities as horses, and have to be as carefully studied if you would ride them fast and far. The lever is put into the most suitable notch for working the steam expansively; the driver's hand is on the regulator, not to be removed for the rest of the trip; the furnace door is thrown wide open, and firing begins in earnest. Here it may not be amiss to state, for the benefit of the uninitiated, that the regulator controls the supply of steam from the boiler, while the lever enables the driver to reverse the engine, or, as we have already stated, to expand the steam by cutting it off before the end of the stroke. The engine answers to the appeal like a living thing, and seems, with its steady beat and sonorous blast, to settle down to its work. It is pleasant from our seat in the corner of the screen to see this preparation for the work ahead—the absolute calm of driver and stoker, who exchange no word, but go steadfastly and quietly about their business; to feel the vibrations from the rails beneath throb through one with slowly increasing rapidity, or watch the trees and houses go past as gulls flap past a boat. For there is a certain apparent swagging movement of the objects past which one travels which can only be likened to the peculiar flight of a large sea-bird. But now there are signs of increased activity on the foot-plate; the stoker is busy controlling the feed of water to the boiler, and fires at more frequent intervals; the driver's hand moves oftener as he coaxes and encourages the engine along the road, his slightest gesture betraying the utmost tension of eye and ear; the stations, instead of echoing a long sullen roar as we go through them, flash past us with a sudden rattle, and the engine surges down the line, the train following with hot haste in its wake. We are in a cutting, and the noise is deafening. Looking ahead, we see an apparently impenetrable wall before us. Suddenly the whistle is opened, and we are in one of the longest tunnels in England. The effect produced is the opposite of that with which we are familiar in a railway carriage, for the change is one from darkness to light rather than from light to darkness. The front of the fire-box, foot-plate, and the tender, which had been rather hazily perceived in the whirl of surrounding objects, now strike sharply on the eye, lit up by the blaze from the fire, while overhead we see a glorious canopy of ruddy-glowing steam. The speed is great, and the flames in the fire-box boil up and form eddies like water at the doors of an opening lock. Far ahead we see a white speck, which increases in size till the fierce light from the fire pales, and we are once more in open day. The weather has lifted, the sky is gray, but there is no longer any appearance of mist. The hills on the horizon stand out sharply, and seem to keep pace with us as the miles slip past. The line is clear; but there is an important junction not far distant, and we slacken speed, to insure a prompt pull-up should we find an adverse signal. The junction signals are soon sighted; neither caution nor danger is indicated, and, once clear of the station, we steam ahead as fast as ever. One peculiarity of the view of the line ahead strikes us. Looking at a railroad line from a field or neighboring highway, even where the rails are laid on a steep incline, the rise and fall of the road is not very strikingly apparent. Seen through the weather-glass, the track appears to be laid up hill and down dale, like a path on the downs above high cliffs. Over it all we advance, the engine laboring and puffing on one or two heavy gradients, in spite of a full supply of steam, or tearing down the inclines with hardly any, or none at all and the brake on. And here it may be noted that, like modern men, modern engines have been put upon diet, and are not allowed to indulge in so much victual as their forefathers. The engine-driver, like the doctor of the new school, is determined not to ruin his patient by over-indulgence, and will tell you severely enough that "he will never be guilty of choking his engine with an over-supply of steam." In the mean time, the character of the country we travel through has changed. It has become more open, and there is a stiff sea-breeze, which makes itself distinctly felt through the rush of air produced by the speed at which we are going. We fly past idle streams and ponds, and as the steam swirls over them are disappointed at producing so little effect; but the ducks, their inhabitants, are well used to such visitations, and hardly deign to move a feather. Suddenly we plunge into a series of small chalk cuttings, and on emerging from them find ourselves parallel with a grand line of downs. We speed by a curve or two, and find ourselves on the sea-shore; one more tunnel, and with steam off we go soberly into the last station. But there is one step more. The breeze blows about our ears. Before us the rails are wet, for the sea swept over them not many hours since, and to accomplish the last few yards of our journey the lever controlling the sand-box must be used liberally, to prevent slipping; the signal is given, and at a walking pace we make our way to where the steamer is awaiting us. A gentle application of the brake pulls us up, and the journey is over. It is difficult to realize, as the engine stands quietly under the lee of the pier while the driver examines the machinery, and the fire, burned low, throws out a gentle warmth as we stand before it, that half an hour ago we were tearing along the line at full speed, while the foot-plate that is now so pleasant to lounge on throbbed beneath us. Nothing now remains but to kill time as best we may till the return trip many hours hence. It scarcely promises to be as comfortable as our morning ride, for the weather has changed—it is blowing half a gale, and the rain comes down in sheets. Our train is timed to start in the small hours, and the night seems dirty and depressing enough as we make our way for a cup of coffee to the refreshment room, where a melancholy Italian sits in sad state eating Bath buns and drinking brandy. We walk past the train, laden with miserable sea-sick humanity, and step on the engine, which stands in the dark at the end of the platform. Time is up, and we pass from the dim half-light of the station into outer darkness. A blacker night there could hardly be; looking ahead there is nothing to be seen but one's own reflection in the weather-glass. We are in the midst of obscurity, which suddenly changes to a rich light as the whistle is opened and we enter a tunnel. The effect is far more striking than in the daytime. The light is more concentrated, and the mouth of the tunnel we have just entered might be the entrance to Hades—for there is no telltale spot of light to prove to our senses the existence of any opening at the other end. The sound echoed from the walls and roof has a tremendous quality, and resolves itself into a grand sort of Wagnerian rhythm, making a vast crescendo, till with a rush we clear the tunnel, and are once more under the open sky. The pace is increasing, the steady beat of the engine tells more distinctly on the ear than in the daytime; the foot-plate is lit up by the glare from the fire-door; but still there is nothing to be seen ahead but the impenetrable night. Looking back, however, the scene is very different. The tender and guard's van glow in the light thrown by the fire, trees and houses by the side of the track stand out sharply for a moment and are then lost to sight, the light from the carriage windows produces the effect of the wake of a ship seen from the stern. Gradually the clouds have rolled away, leaving the sky clear. The moon is seen fitfully through the whirling steam; the surrounding country is visible for miles round. The effect produced is unspeakably beautiful. In the mean time let us turn our attention to the working of the engine. In the first place, let us take note that, although the engine we are now on, and that which took us from London, belong to the same type, their performances are somewhat different. No two engines ever resemble each other, no matter how carefully they may have been built from the same plan, neither do any two drivers manage their engines precisely in the same way. We have in this instance an excellent opportunity of comparing two different methods of driving. It is the driver's principal object to get the required amount of work out of his engine with the smallest possible expenditure of coal and water. To obtain this result the steam must be worked expansively, which is done by placing the valve gear in such a position by means of the lever that the supply of steam to the cylinders is cut off, as we have stated at the beginning of this article, before the piston has accomplished its full stroke. There are two ways of controlling the speed of an engine worked, as all locomotives are worked now, expansively. You may keep the regulator wide open, so that there is always a full supply of steam on its way to the cylinders, in which case you increase or diminish the speed by using the steam more or less expansively through the agency of the lever. Or you may work with the same amount of expansion throughout the journey, and have command of the engine by constantly changing the position of the regulator. There is no doubt that the men who employ the latter method save something by it, although this would hardly seem to be the opinion of the driver who is bringing us rapidly nearer to London, for unlike the driver whom we accompanied on the daylight journey, his hand is not often on the regulator. As we rush on past countless signals, punctual to the minute, yet always having ample time to slacken speed before we come to the places where the different colored lights cluster thickest, we are reminded once more how much is required of an express engine-man besides a thorough acquaintance with the machinery he has to control. Traveling at night at a great speed, he must know every inch of the road by heart—where an incline begins and where it ends, and the exact spot at which every signal along the line may be first sighted. He must have completely mastered the working of the traffic on both the up and down lines, and, above all, must be ready to act with the utmost promptitude should anything go wrong. Mr. Michael Reynolds' publications have done much toward enlightening the public on these points, but we doubt if there are many who really know the amount of toil and danger cheerfully faced by the men on the engine, who hold their lives in their hands day after day for many years. These thoughts occur to us as we recross the Thames and pull up at the platform after a thoroughly enjoyable run.—Saturday Review.
The mucilage on postage stamps may not be unhealthy, but persons having a good many to affix to letter envelopes, circulars, newspapers, or other wrappers every day, will consume considerable gum during a year. A less objectionable mode of affixing stamps than the one usually employed is to wet the upper right hand corner of the envelope, and press the stamp upon it. It will be found to adhere quite as well as if the stamp went through the moistening process.