SOME SIMPLE RULES.

The study of the physiological influence of the wave of low temperature, and of its relation to the wave of mortality, suggests a few rules, simple, and easily remembered.

1. Clothing is the first thing to attend to. To have the body, during variable weather, such as now obtains, well enveloped from head to foot in non-conducting substance is essential. Who neglects this precaution is guilty of a grievous error, and who helps the poor to clothe effectively does more for them than can readily be conceived without careful attention to the subject we have discussed.

2. In sitting-rooms and in bedrooms it is equally essential to maintain an equable temperature; a fire in a bedroom is of first value at this season. The fire sustains the external warmth, encourages ventilation, and gives health not less than comfort.

3. In going from a warm into a cold atmosphere, in breasting the wave of low temperature, no one can harm by starting forth thoroughly warm. But in returning from the cold into the warm the act should always be accomplished gradually. This important rule may readily be carried in mind by connecting it with the fact that the only safe mode of curing a frozen part is to rub it with ice, so as to restore the temperature slowly.

4. The wave of low temperature requires to be met by good, nutritious, warm food. Heat-forming foods, such as bread, sugar, butter, oatmeal porridge, and potatoes, are of special use now. It would be against science and instinct alike to omit such foods when the body requires heat.

5. It is an entire mistake to suppose that the wave of cold is neutralized in any sense by the use of alcoholics. When a glass of hot brandy and water warms the cold man, the credit belongs to the hot water, and any discredit that may follow to the brandy. So far from alcohol checking the cold in action, it goes with it, and therewith aids in arresting the motion of the heart in the living animal, because it reduces oxidation.

6. Excessive exercise of the body, and overwork either of body or of mind, should be avoided, especially during those seasons when a sudden fall of temperature is of frequent occurrence. For exhaustion, whether physical or mental, means loss of motion in the organism; and loss of motion is the same as loss of heat.

One further consideration, suggested by the subject of this paper, has reference to the bearing of the public toward the labors of the medical man in meeting the effects of the low wave of heat. The public, looking on the doctor as a sort of mystical high priest who ought to save, may often be dissatisfied with his work. Let the dissatisfied think of what is meant by saving when there is a sudden fall in the thermometer. Let them recall that it is not bronchitis as a cause of death, nor apoplexy, nor heart disease, as such, that the doctor is called on to meet; but an all-pervading influence which overwhelms like the sea, and against which, in the mass, individual effort stands paralyzed and helpless. When the doctor is summoned the mischief has at least commenced, and, it may be, is so far over that treatment by mere medicines sinks into secondary significance. Then he, true minister of health, candid enough to bow humbly before the great and inevitable truth, and professing no specific cure by nostrum or symbol, can only try to avert further danger by teaching elementary principles, and by making the unlearned the participators in his own learning.—The Asclepiad.

THE TREATMENT OF GLAUCOMA.

As this disease is so fatal to vision, any remedy that may be suggested to diminish the frequency of its termination in blindness cannot fail to be read of with interest. M. Nicati, in the Revue generate de clinique et de therapeutique, has had marked success in the treatment of glaucoma by drainage of the posterior chamber, either by sclerotomy or by sclero-iritomy, as the conditions of the individual case may require.—N.Y. Med. Jour.

A TWIN SCREW LAUNCH RUN BY A COMPOUND ENGINE.

The launch shown in our illustration was built in New Westminster, British Columbia, Canada. She is 42 ft. keel and 7 ft. beam, and has 4 ft. depth of hold. She has an improved Clarke compound engine, also shown in an accompanying illustration, with a high pressure piston four inches in diameter, and a low pressure piston eight inches in diameter, the stroke being six inches, and the engine driving two twenty-six inch screws. With 130 pounds of steam, and making 275 revolutions per minute, the launch attains a speed of nine miles per hour, thus fully demonstrating the adaptability of this engine to the successful working of twin screws.

In the Clarke engine, the exhaust pipe from the high pressure cylinder leads to the steam chest of the low pressure cylinder, while the piston in the upper cylinder is secured on a piston rod extending downward and connected with a piston operating in the lower cylinder, the exhaust pipe from the latter leading to the outside. On the piston rod common to both cylinders is secured a crosshead pivotally connected by two pitmen with opposite crank arms on crank shafts mounted to turn in suitable bearings on the base, which also supports a frame carrying the low pressure cylinder, on top of which is a frame supporting the high pressure cylinder. The valves in the two steam chests are connected with each other by a valve rod connected at its lower end in the usual manner with the reversing link, operated from eccentrics secured on one of the crank shafts.

The crank arms stand at angles to each other, so that the crank shafts are turned in opposite directions, and the position of the link is such that it can be readily changed by the reversing lever to simultaneously reverse the motion of the crank shafts. On the crank shafts are also formed two other crank arms pivotally connected by opposite pitmen with a slide mounted in vertical guideways, supported on a frame erected on the base, the motion of the crank shafts causing the vertical sliding motion of the slide traveling loosely in the guideways, and thus serving as a governor, as, in case one of the propellers becomes disabled, the power of the shaft carrying the disabled propeller is directly transferred to the other shaft through the crank arms, pitmen, and slide, and the other propeller is caused to do all the work. All the parts of the engine are within easy reach of the engineer, and there are so few working parts in motion that the friction is reduced to a minimum.

It is said that the plan of construction and the operation of this engine have been carefully observed by practical engineers, and that, considering the dimensions of the boat, her speed, the smallness of the power, the ease with which she passes the centers, the absence of vibration while running, and the very few working parts in motion, the engine is a notable success. She can be run at a very high velocity without injury or risk, and is designed to be very economical in cost and in weight and space. This engine has been recently patented in the United States and foreign countries by Mr. James A. Clarke, of New Westminster.

IMPROVEMENTS IN THE CONSTRUCTION OF RIVER AND CANAL BARGES.

By M. RITTER (KNIGHT) VON SZABEL, late Austrian Naval Officer, of Vienna.

This innovation consists essentially in an arrangement by which two distinct vessels, on being revolved round their longitudinal axis to an angle of 90°, can be combined into one single duplex vessel, or, to put it in different words, a larger vessel is arranged so that it can be parted into two halves (called "semi-barges"), which can be used and navigated with equal facility as two distinct vessels, as if combined into one. By the combination of the two semi-barges into one duplex barge the draught of the vessel is nearly doubled, the ratio existing between the draught of a loaded semi-vessel and the equally loaded duplex vessels being 5:8 (up to 8.5)

The advantage of the invention consists:

1. In this difference of draught.

2. In the smaller width of the semi-vessel as compared with the duplex vessel.

3. In the fact that the combination and separation of the vessels can be effected, without the least disturbance of the cargo, in a minimum of time.

It facilitates the utilization, to the highest possible extent, of the varying conditions and dimensions of canal locks and rivers.

The transition from rivers to canals, and from larger canals to smaller ones, is expedited by the possibility afforded of, on the arrival at the locks, dividing the vessel in a space of a few minutes; of passing with the semi-vessel, singly, the various smaller locks or the shallow canal, after which the two sections may be re-combined and navigated again as one vessel. The process of "folding up" the two vessels will of course take longer than that of separation.

On rivers, the channels of which are interrupted by sand banks and rapids, the same operation may be carried out, thus avoiding the expense and delay necessitated by, perhaps, repeated "lightering," i.e., reduction of the cargo.

Thus, the through traffic on large rivers like the Danube, with its repeated obstacles to navigation, such as the "iron gate," and several sand-banks known and dreaded by bargemen, would be materially facilitated, any necessity for unloading part of the cargo being obviated; moreover, such a duplex vessel composed of two semi-vessels affords the advantage of utilizing to a fuller degree the power of traction, and one large vessel will be more convenient for traffic than two smaller ones.

Further, the mode of construction of the semi-vessels—both ends of which are of a similar pattern—allows of their being navigated up and down a water channel without the necessity of turning them round; provision having also been made for the fixing of the rudder at either end, which would therefore merely require exchanging. This is of some advantage in narrow river beds and canals, and applies equally to the duplex vessel as to the single semi-vessels.

Each semi-barge on its part is also constructed of two equal halves—which are, however, inseparable—and as there is no distinct stem or stern, any one of these semi-vessels will fit any other semi-vessels of the same dimensions, and can be attached to the same by means of the coupling apparatus, and the two "folded up" into one duplex vessel. This process does not present any material difficulties. The two single boats on being coupled together can be made to lean over toward each other, by filling their lateral water compartments, to such an extent that the further closing up can be easily effected by means of specially constructed windlasses. In the case of petroleum vessels the "folding up" operation is facilitated by the circumstance that the petroleum may be made to serve the purposes of water ballast.

As regards the size and tonnage of the new vessels, this will of course depend on the local condition of the rivers and canals to be navigated. Thus a vessel destined for traffic on canals with locks of varying dimensions will have to be adapted to the dimensions of the smallest existing lock.

Supposing the size of the latter to be such as found in the case of the Rhine-Marne or the Rhine-Rhone Canal, or on the Neckar down to Cannstadt, or in the Danube-Main Canal and some smaller canals in the Weser district, etc., viz.:

Length of lock34.5 meters.
Width5.2 meters.
Depth1.6 to 2.0 meters.

The semi-barge may be made 32 meters in length, 4 meters in breadth and 2.5 meters total depth, and with a draught of 1.5 meters will be capable of carrying a load of 100 tons (of 1,000 kilos each). Correspondingly the duplex vessel will be able to carry 200 tons, with a minimum draught of 2.4 meters and a width of 5.4 meters, but, with a favorable height of the water level, the draught of the semi-barge may be increased to 1.65 and that of duplex vessels to 2.7 meters.

Where not limited to certain proportions by the dimensions of the locks to be passed, the vessel may in the first place be made longer; the width and height may also be increased accordingly (provided that the proportion of breadth to width is kept within the ratio 4:2.5), so that the semi-barges may be constructed for a single burden up to 300 tons, or 600 for the duplex vessel.

As regards the nature of the cargo, parcels would not be admissible in this instance, but any kind of homogeneous cargo would be suitable which would bear laying over on one side.

Thus this style of vessel would be well adapted for petroleum tank vessels, for the transport of all kinds of cereals, flour, coffee, and sugar in sacks—these latter being held in position by an arrangement of planking and boards so as to prevent any overturning of the goods on the vessels being folded up or taken apart. Similarly in the case of a cargo of loose grain or other loose produce, the same must be prevented from being upset by a kind of wooden casing.

Two semi-vessels loaded with different cargoes may be coupled together, provided that there is not too much difference between their respective draughts. Slight differences may be balanced by the water compartments being filled to a greater or smaller extent.

The peculiar position of the hatches allows of loading the semi-vessels separately as well as when coupled together.

If there is for the time being no necessity for using the vessels in their capacity of separate and duplex barges, any kind of cargo might be loaded that does not require large hatches.

The vessels, on account of their more complicated construction, will be somewhat more expensive, but wherever the advantage offered by them outweighs the extra expenditure, they can be used with success.

The innovation might be of particular importance where a new canal system is being constructed, since the latter might be subdivided into main canals and branch canals—similarly as in the case of ordinary and narrow gauge railways—the main canal being built of a larger section and with larger locks to suit the duplex barges, while the branch canals could be planned of smaller dimensions calculated to suit the semi-barge. Thus the first cost of such a canal system would be materially reduced as compared with a canal installation of one uniform section throughout.

Likewise in mountainous districts with rock soil it would be an important consideration whether a canal had to be blasted out of the solid rock or a tunnel cut, in dimensions suitable for a vessel of 6 or of 14 square meters section below the water line.

In this case, even in certain portions of a main canal—where rendered desirable by the rocky nature of the ground—a smaller section might be adopted, which would only be large enough for single semi-barges, so that the duplex vessel would in these instances have to be taken apart in the same way as in a branch canal.

The saving to be effected by constructing a canal on this principle, as compared with a canal of one uniform section throughout, must be considerable, and the advantages of the arrangement are apparent.

These Figs. 4 and 5 will also serve to illustrate the manner in which sacks and loose produce should be loaded. Fig. 4 also shows the filled water compartments, and the effect of their weight in making the boats lean toward each other.

The materials most suited for this new style of vessel will be iron and steel such as generally used in the construction of canal and river vessels.

The new ship can be moved by any motor or driving implement, nor could there technically a great difficulty be found for making the boilers move on a quadrant-like rail base in the shape of a circle segment's quarter, or for building a double screw steamer by combining two single screw propellers.

May be a ship owner is willing to submit the innovations to an attempt, so much the more as there is running no great risk by doing so; for in case the ships should not answer the expectations, both separable as well as joinable, they can be used like single ships, without any further alteration being made, except as to the loading gaps.

The above invention is covered by United States patent No. 435,107. Any further information may be had by addressing M. v. Szabel, ix Bezirk, Beethovengasse 10, Wien, Austria.

WELDON'S RANGE FINDER.

Colonel Weldon has recently considerably modified and improved his ingenious range finder, and we illustrate herewith from Engineering the form in which it is now manufactured. It consists of a metal box, the lid of which is shown open in the engraving, and on this lid are fitted three prisms which are the essential constituents of the instrument. When the lid is closed, these, with the compass and level, also attached to the lid, lie inside the metal box, and are thus thoroughly protected. The upper prism marked 1 is a right-angled one and is mounted with the right angle outward; looking into the left-hand corner of this prism one will see in it, by double reflection, objects lying on one's right hand. Below this is a second prism with a principal angle of 88 deg. 51 min. 15 sec., and below this a third with a principal angle of 74 deg. 53 min. 15 sec.

A longer base, and probably greater accuracy, can be obtained by using the second prism only, as indicated in Fig. 3, in which case the distance of the object is 25 times the distance BC. This second prism is, however, best adapted for predicting the range of moving objects. Three observers are required. Two of them have finders, while the other measures the distance between the two. The first two observers separate, and No. 2 takes a position such that the object is reflected to one side of observer No. 1, whom he views by direct vision. As the object continues to move, its image gets nearer and nearer No. 1, who during the whole of the time moves a little to one side or the other, so as to keep the image of the object constantly in line with No. 2. Just as the image of the object gets very near No. 1, No. 2 calls out "Ready," the distance between the two observers is taken by the third, and when the image of the object actually falls on No. 1 its distance is just 25 times the distance between them, and the guns set to this range are fired by word of command from No. 2.

By using the third prism in conjunction with the second a still longer base of one-fourth the distance of the object can be employed. The range finder can also be used as a depleidoscope for transit observations. For this purpose it is mounted on a block of wood by means of elastic band and leveled by the level on its lid, being at the same time set in the meridian of the place. The lid is opened to make an angle with the horizon equal to the latitude of the place of observation. On looking into the upper prism two images of the sun will be seen on each side of the apex of the prism, which gradually approach each other as the sun nears the meridian, and finally coincide as it passes it, the time of which being noted gives the longitude of the place.

Extensive trials of the instrument have been made both in this country and in India, which agree in showing that the average error in using the instrument is about 2½ to 3½ per cent.

WHEELS LINKED WITH A BELL CRANK.

FIG. 1

There are four ways in which a connecting rod is made use of in machine work. The first is in linking two wheels together that stand in the same position, but a slight distance off centers. The rod in this case has only to lead the driven wheel around by connecting it with the driver, and consequently has only to endure a pulling strain in the direction of its length. The second is when the rod is called upon to stand a pull and a push at every revolution. The third takes in the matter of the twisting strain that a rod can manage; but the fourth brings the hardest usage that a connecting rod can be called upon to endure, and that is by making a lever of the rod to get a driving action by prying on a fulcrum in the center. In Fig. 1 is seen a case of this kind taken from a machine in which a disk engine was made use of. The rod has a chance to turn about on its center from a ball and socket joint, and engages with both wheels in nicely fitted journals, and boxes set in line with the center of the socket joint, so that when one wheel turns, the rod pries the other around by using the rod as a lever and the ball joint for a fulcrum, giving a uniform leverage all the while, with no dead centers.

FIG. 2

To set this arrangement around at right angles, or where the shafts will bring the wheels together, as for bevel gears, a bent lever arm would need to be used, as shown in Fig. 2, but the bend in the connecting arms brings in another feature that must be provided, as it allows the wheels to turn either with or against each other, and leaves two places where the bent arms will come to a dead center. What is needed here is another element that will take all the twisting strain on the rod and keep the pitch of both arms alike in every portion of a revolution. To do this the ball and socket joint will need to be replaced by a gambrel joint like a ship's compass, and arranging the bent driving arms as shown in Fig. 3; then the driving end of the connecting frame will move about in a true circle, producing as great a tendency to turn the driving wheel in one position as another. In this arrangement there must be at least six nicely fitted journals and their bearings, four of which will be required to take care of the forked connecting rod that joins the wheels together. Besides all this the bearings must all line up with the same center that the shafts are centered from or there will be a "pinch" somewhere in the system. It may seem at first that there must be more or less end-on movement provided for, and that the bearings should be spherical; but that it is not the case will be noticed when all the points are understood to be working from one center similar to that provided for in bevel gears.—Boston Journal of Commerce.

FIG. 3.

THE DECORATIVE TREATMENT OF NATURAL FOLIAGE.[1]

By HUGH STANNUS.

Lecture I.