a face cap. These are the essentials.

An iron cylinder 31⁄2 by 21 inches contains the oxygen åt a pressure of about two thousand pounds when completely filled. This life-sustaining gas also furnishes the energy required to induce breathing in the following manner:

The oxygen from the tank flows through the reducing valve, which at the outlet side maintains a pressure of about seventyfive pounds, and from there to the controlling valve. Initially, the passage to the lungs is open through the controlling valve. The latter connects to rubber tubes leading to a metallic face cap with a rubber rim that closely fits the patient's face. The face

cap on one side is provided with a rubber bag, which permits a pair of forceps to protrude by means of which the patient's tongue is held from obstructing the pharynx. The oxygen then has free access to the lungs.

When the pressure in the lungs has reached a certain value, about normal, a bellows interconnected with the lung cavity through the rubber tubes actuates the controlling valve. The pressure of the oxygen is now directed so as to cre

ate a suction over the connections which lead to the lungs, thereby causing exhalation of the gases previously forced upon the lungs. When a certain vacuum is reached in the lungs and bellows, the outer atmosphere acts upon the latter, which, in turn, operates the controlling valve and again admits the oxygen to the lungs. The frequency of these reversals depends upon the size of the lung cavity, a larger space requiring greater time, while with smaller lung capacity the operation is correspondingly more frequent.

This process is continued until the patient shows signs of natural respiration. The pulmotor action is then discontinued and the patient is allowed to breathe the pure oxygen through the other small face cap connected by a hose with the oxygen tank.

The action of the pulmotor is started simply by the attachment of the instrument to the patient through the rubber face cap and the turning on of a switch that regulates the shutoff and shuton of the battery. The fact that its own battery is attached makes possible the use of the pulmotor anywhere. There is no need of an electric current in the house where the asphyxiation has occurred.

T has been proposed to mend Niagara Falls, for its Beauty's sake. For For some years now the engineers have been tinkering with Niagara in the interest of Industry and Power; but this newest scheme will involve some skill, not for business, but in the interest of Nature's good looks.

The Horse-Shoe Fall, between Goat Island and the Canadian shore, has long been admired for the circling contour as well as for the grandeur of the cataract. But it seems that there has been gradually a getting away from that shape.

The power works have had a contracting influence and have tended to concentrate the force of the cataract upon its center. There was always, to be sure, a tendency in this direction, but the engineering liberties that have been taken have apparently added to it. The result is that the Horse-Shoe Fall is now pouring with such force over the central part of the precipice that it is wearing away the rock.

The photograph is taken from the water's edge on the Canadian side, just where it tumbles over. One may see how the outline of the waterfall is indented, running away back into the channel of the river. That is the spoiling of the horse-shoe. The photograph somewhat exaggerates the indentation, perhaps, and gives it too square a look, because the view is lateral and loses the impression of width which gives the circling shape: if the camera could have

been set directly in front, and at the same level, it would have shown that the apex of the horse-shoe is V-shaped, to the disadvantage of its scenic effect.

For many hundreds of years Niagara has been wearing back on its ledge of rock. It would, of course, be impossible that a low-water discharge of 168,700 cubic feet per second could continue day and night for centuries without some wear and tear on the rock that it tumbles over; and the precipice of the Falls is today seven miles up-stream from where it began ages ago. The wearing process is still going on, but there's a difference. Seven miles of rock-eating went on with no one to see or care: a few feet of it nowadays brings observing men to attention with an engineering scheme.

That scheme is nothing less than filling up the V-shaped crevice and restoring the horse-shoe. Temporary towers to be erected on the Canadian shore and Goat Island, and between these to be stretched a double cableway; huge blocks of concrete then to be carried across this cableway, directly over the crevice, and dropped straight into it-that is the plan. There is no telling how much of this concrete stuffing would be required, for the depth of the erosion is unknown, but it is believed that the crevice can be filled and the waterfall set forward again to its original line. It is at this point that the greatest volume of water goes over, and the wearing-away is likely to do further mischief unless arrested.

HINK of a three-fourths horsepower steam turbine, the moving parts of which are so small you can hold them in the palm of your hand, then think of the possibilities of such an engine built in large proportions. One can hardly realize that such power lies dormant in a simple pair of spiral gears, yet they form the active part of the most powerful turbine in the world for its size.

The engine is the invention of Mr. John H. VanDeverter and is of a design hitherto unheard of in engineering practice.

The entire plant consists of two gears, or rotors, as they are called, revolving in a closely fitting double cylinder.

Imagine these rotors turned over so that the pocket formed between the gears at the point A faces downward underneath the machine. Each tooth of the gears as it passes this point gets the benefit of the impact force of the steam or, in other words, its blowing pressure against the teeth.

As the rotors turn past this point in the direction indicated by the arrows, the steam just admitted into the V-shaped groove is completely shut off and expands until it reaches the stage indicated by the ends of the outer

white lines, where its expansive power is fully expended and it passes out of the gears in a practically dead condition.

The great power developed in so small a space is explained by the fact that there are eighty thousand impacts or pressures against the gear teeth a minute, and the same number of expansions in the grooves, one for each tooth passing the point where the steam enters, the average speed of the turbine being about two thousand revolutions per minute.

As compared with electric motors the new turbine is smaller for the same horse power, and is from twenty to fifty per cent more economical to operate than other turbines of the same size, chiefly because of the great waste of energy through leakage in the fan type.

There are but two points exposed to wear, the bearings and the contacts of the gear teeth. In the former this difficulty is

almost entirely overcome by the fact that each bearing acts as a pump supplying itself with oil from a reservoir and maintains a film of oil over the bearing surfaces as long as the engine is running.

In the case of the contact of the gear teeth a film of steam surrounds these at all times when in operation so that they are cushioned from each other.

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LONG with the interurban and the automobile has come another factor in bringing closer together the town and the country, in revolutionizing farm home conditions and in keeping the boys and girls on the farm. This new factor is the motorcycle. One prominent manufacturer reports that he sold four thousand motorcycles to farmers last year, with every prospect good for the number reaching the ten thousand mark this year. Already, one farmer out of every eight in Indiana owns and uses a power-driven bicycle, while throughout the entire Middle West the familiar chug and snort of the motorcycle, ridden by some farmer, is weekly becoming more common.

The adoption of the motorcycle by the farmer, as a sort of compromise between Old Dobbin and the automobile, has un

doubtedly come about as a result of his discovery that the motorcycle is valuable not only as a vehicle of pleasure but as a quick means of transporting small burdens. In many instances the motorcycle is being used to haul cans of cream, bags of meal, poultry and small garden truck from the farm to the city, the speed with which it is possible to travel over the ordinary country road being one of the reasons for its growing adoption. The fact that most of the standard makes are equipped with carriers capable of holding a two hundred-pound load makes the motorcycle appeal to the farmer, who has learned, by experience, that it is not always economy to take the horses from the necessary work of the farm in order to make a trip to town.

In still another important respect is the motorcycle coming to figure prominently