UST as the torpedo boat brought forth the torpedo boat destroyer, so now the Zeppelin has caused the invention of Zeppelin-destroy

ers. Two hundred and thirty feet long, built of wood, looking like great torpedoes, England's new Zeppelin-destroyer dirigibles are almost ready to make their appearance. Beside Germany's great airships, they will appear like little pencils, silhouetted against the sky; but they will be capable of a speed of sixty miles an hour, and they will be able to discharge an aerial torpedo point blank at a mark sixteen hundred feet away.

The new airships are the invention of an American, Thomas Rutherford Macmechen, who heads the company which is building them. Equipped with two light engines, and manned by a crew of four men, the machines are designed expressly for the defense of the island. They will be exceedingly mobile and fast, but will be worthless more than seventy-five miles from their base. They will be able to stay in the air for ten hours, send wireless messages, and to attack their great enemies in their own way. Each ship is to be operated entirely by the navigator with the aid of a set of control buttons which are connected to rudder, planes and even engine. The destroyers have no hanging car, for the riding compartments are built in as part of the wooden covering of the fourteen different gas bags which form the sustaining power.

The wooden construction is the strongest possible for the weight of the whole ship. Laminated spruce in thin strips is wound around the hull in spiral shape and the whole then covered with weatherproofed cloth which is impregnated with metal so that the ship will shine like a nickel-plated cigar in the air. The shine will make the hull very difficult to see and to aim at.

By authorizing the construction of this type of craft, English officials have admitted that the raids which have already been attempted have shown the possibilities of attacks on a large scale, and that they fear the fleet which Germany has been rapidly augmenting. Furthermore, they are not satisfied with the present means of defense against a raid by half a hundred Zeppelins, since these raids have demonstrated the failure of the high angle guns.

Experts of other countries have also noted that the searchlights, which Paris and London placed on their roofs in great numbers when the war first began, have disappeared. They had hardly been. mounted before someone discovered that each beam was like a beacon which guided the enemy to the heart of the city. Then the high angle guns, which London mounted throughout the city, were condemned, since the shells from them would descend on the city and be as dangerous as aerial bombs. The Zeppelin-destroyers are to be depended upon for defense in the great raid that England expects nightly.

BALTIMORE PAVING

INVIOLATE

proper direction, concentrating the illumination on the goods displayed.

As most of the light given by the bulb falls beneath the fixture itself, the lamp is of peculiar value for show windows, factories and offices. In a comparison with an ordinary tungsten lamp, both being twenty-five candle-power, the new shape gave full illumination, directly below, while the old shape gave from but four to seventeen. The light is to be made in standard sizes.

ONCE new paving has been laid in the city of Baltimore, no permit to disturb it can be issued until a period of five years has elapsed. The most common municipal nuisance is to have all property owners and gas companies wait until a street has been paved before they signify their intention of having new water pipes or gas pipes, or other underground structures, put in; but in Baltimore, signboards notify the public in advance when a street is to be reworked, advertisements in the newspapers add a warning, and notices are sent to all property owners adjoining the improvement, reminding them of the law. As a result, every pavement is guaranteed a life of five years, provided no accident occurs. At the expiration of that period, no loss will occur if the paving should be cut, since, in all probability, it would need some repairs.

A BENEVOLENT VOLCANO THAT HAT a volcanic eruption may result in some good to its supposed victims is shown on Kodiak Island in

29c

HOW THE NEW BULB ILLUMINATES The distance of the lines from the bulb, at any one point, shows how much light is given at that point. The heavy line for the new lamp, is much further than the broken everywhere that illumination is desired.

the Alaskan sea. When the great eruption of Mt. Katmai occurred, two years ago, the native population was driven out by sulphurous fumes, and the vegetation famous for its cattle-fattening qualities was blotted out under a heavy fall

rains of two winters have pressed the ash into the soil, where it has acted as a wonderful fertilizer. The grass is more luxuriant than ever, and cattle again are being fattened on the island, to be shipped in turn more than one thousand miles south to the markets of Puget Sound. The increased returns will more than pay for damages.

SEALS SALT FROM
AIR AND MOISTURE

To avoid the difficulty of getting salt

from the table shaker in damp weather, an ingenious inventor has devised a salt shaker that excludes all air from the salt, thus keeping the salt dry. The inside of the shaker is formed to provide a seat for a globular valve,

GIVES SALT IN WET WEATHER

The bulb beneath the top seals the salt when not needed, and thus keeps it perfectly dry.

LOS ANGELES

70.9%

which has a stem projecting through the perforated top or sifting cover. The valve acts automatically by gravity, falling into the closed position as soon as the shaker is placed upright. Thus it seals the salt and protects it against air and moisture. The usual motion opens the valve, allowing the salt to sift out through the perforated cover. Refilling is accomplished in the ordinary way, the valve lifting out with the cover when this is unscrewed. In fact the shaker works differently from others only by being perfect.

NEW METER TELLS GASOLINE CONSUMPTION

A NEW meter for gasoline, petroleum,

crude oil, etc., to be used in connection with all kinds of engines using liquid fuel, especially automobiles, is an important factor in determining efficiency.

The construction of the device is very simple, resembling in many ways that of a water meter. It will register very accurately the amount used regardless of the flow or the variation of pressure. The meter is placed on the dashboard of an automobile in full view of the driver and tells him the consumption of gasoline for each trip, or for a day or a week, and so on. In stationary plants, it may be used to determine the fuel consumption of different engines, or of the same engine at different speeds, thus helping greatly in determining the efficiency of the units and of the speeds.

PITTSBURG

49.0%

OVERHEAD

FROM one to three holes

may be bored overhead at one time with a new brace that is designed to run holes for electrical wiring through joists. The device also does away with the use of the stepladder and ordinary brace and bit.

A steel clamp fastens the tool to the joists in a moment, a long shaft runs to a convenient height from the floor,

and from there the workman turns the brace. The tool can be taken down as quickly as it is put up.

The tool is also equipped with a small set of gears that can be attached to bore three holes at one operation. A much neater job is done in this way, since in a line running across a large number of joists, all holes are exactly in line with each other.

PERFECT AUTOMATIC TWINE KNOTTER

SINCE the adoption of harvesting machinery, the problem of knotting twine automatically has baffled the inventor until now. It seems, however, that a knotter that will tie any size of twine, has at last been perfected. It op

BORES HOLES OVERHEAD

A new brace that cuts down the electrician's work immensely.

USING EACH BRACE The superiority of the new device is obvious.

erates as well with a material of soft fiber as with any other, and is said to help considerably in lowering the twine bill.

The device is a small affair and can be attached to any type of harvesting machinery. It is fed into the knotter, and does the work automatically.

M

ANY people who buy a car rated at, say, twenty-five horsepower, have an idea that their car is powerful enough to hold at a standstill twenty-five horses pulling in the opposite direction. It is possible that they would be entirely right-provided the horses were exactly alike, and each one exerted exactly the same force.

But in most cases, the rated horsepower of an automobile is far from indicative of the number of horses it could drag along a road. "One horsepower" is simply a term which means the amount of power needed to raise thirty-three thousand pounds one foot in one minute. This is far more power than any horse possesses; probably the heaviest Percherons could not exert more than threequarters as much. Furthermore, "horsepower" means lifting power; and one horsepower-that is, the amount of force. needed to raise thirty-three thousand pounds one foot in one minute-is equal to about four times as much power, when applied in tractive effort—that is, in moving along level surfaces such as roads.

The rated horsepower of an automobile refers to the lifting power. It is determined in a way that actually tests lifting power, though, of course, the engine is not set at work lifting weights. Instead, friction is applied to a wheel which is turned by the engine, and the engine must exert power in turning against the friction, just as though the wheel were winding up a weighted rope.

In order to measure the horsepower of an automobile engine, the engine is mounted on a stationary frame, and a wheel about a foot in diameter is placed

on the shaft. The engine then is started and run at high speed, while a brake is put on the wheel and pressure applied to the brake. Like any brake the effect is to lower the speed of the engine. The harder the brake is pressed, the more the engine slows down; but since the engine is not stopped by the brake, it drags it around a certain distance. The pressure the brake exerts is measured by an ordinary pair of platform scales, of the type that a person gets weighed on; and from this pressure, the power of the engine is determined.

When the engine runs at a given speed and a lever of standard length from the brake presses down on the scales a required number of pounds, the engine is said to be developing one horsepower, because the engine is doing work against the brake that is equivalent to lifting the required weight in the required time. If an engine runs at the same speed and registers twice as many pounds on the scales, it is rated at two horsepower. For sixty times the weight on the scales, the engine would be rated at sixty horsepower. Heat developed by the friction between the brake and the wheel is overcome by water.

Thus it is seen that, though it seems paradoxical, old Dobbin may not be able to deliver one horsepower. However, he has one thing in his favor; he can deliver all he has at once, and often in the most effective place, while the engine must first get up to speed. So on starting a load, one horse can do it quicker than a sixty-horsepower gasoline engine starting from rest. But when the engine gets started the horse is, of course, out of the race in every way.