secutive hours. This means that they operated their arms like delicately poised springs at the rate of between 2,200 and 2,500 vibrations per minute, or nearly forty strokes in a single second.

Telegraphers throughout the country recognized the advantages of a device that eliminated the making of dots by hand. The rise of automatic sending machines was, therefore, rapid and the result has been that dozens of these inventions now are on the market, all utilizing the old mechanical principle of a vibrator in some form or another.

The great trouble with all of the machines, however, has been their lack of portability and the necessity of providing a level resting place for them, for without being level, the action of the vibrator was retarded and the end sought for lost.

It has remained for E. A. Brandenberg, an old-time telegrapher of Los Angeles, Cal., to perfect these devices and bring them to a degree of efficiency and practicability that makes them suitable for all service.

Mr. Brandenberg has evolved a little apparatus which fits over the finger knob of any of the existing Morse keys. In size it is but little larger than the ordinary pocket match case. In it are combined not only the vibrator spring, but the electrical contact point also is equipped with a delicate coiled spring. The advantage in this arrangement lies in the fact that a perfect level is not required in order to operate the machine. Another, and still

greater advantage from the viewpoint of the telegrapher, lies in the fact that the instrument weighs but a few ounces, attaches to an ordinary key wherever it may be found, and is therefore available for use wherever a set of Morse instruments is operated.

Unlike others of the craft who have improved the condition of their fellows, Mr. Brandenberg has given it to the world without cost. He has not secured patents, although he has features which are easily patentable. He has served many years as an operator himself and declares that he is only too glad if, in his declining years, he shall be able to ameliorate conditions for those who may follow him in the profession.

The sending machine is only for those who have mastered the art of telegraphy. It can not be used by the beginner, for the reason that in beginning the novice learns to make the required number of dots by counting them. With the vibrator the dots are so rapidly run off that the beginner cannot stop the machine in time and instead of making three dots, which would constitute a letter "S," he is liable to let it run on a dot further, making an "H," or two dots more, making a letter "P."

The old telegrapher, like the old dog, does not take kindly to new tricks, but the sending machine is being rapidly taken up by men of experience. This is particularly true of men who work fast wires.

N connection with the recent meeting of the International Aeronautical Federation, coinciding with the twenty-fifth anniversary of the founding of the Berlin Aëronautical Society, a novel sport was inaugurated in the German capital, namely, balloon hunting by means of automobiles. As the game is played, it is understood that despatches have been sent out in balloons from a besieged place and the enemy are trying to get hold of these despatches by installing automobiles alongside the road on the lee side

loons were hunted by seventeen automobiles, each of which was attached to a given balloon. The automobiles were allowed an advance of fifteen minutes,

of the town, which as the balloon appears, immediately start in pursuit.

At the meeting in question four bal

A BALLOON RACE ON A LARGE SCALE.

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3OR many years there has been a conflict for supremacy between the makers of heavy armor plate and the manufacturers and inventors of big guns, projectiles and explosives. Down at Indian Head, a point on the Potomac River eighteen miles below Washington, the United States Government has a proving ground where tests are constantly being made to see which can score, the projectile or the armor. Great sections of thick and hard armor plate are set up to represent the side of a warship, and at these targets are fired gigantic shells from huge cannon. Sometimes the projectiles are shattered into a thousand pieces and the armor only disfigured by heavy dents. But often the big missiles succeed in passing through the targets and bury themselves in the clay bluff backing the plate, thus scoring a triumph. The balance of power recently has been on the side of the gun and projectile, but something more than mere penetration is necessary to complete the destruction of a modern battleship. A steel projectile weighing a ton may pass through the side and do but little damage to the vessel. The requirement is for destructive power inside the ship after the armor plate has been penetrated. Projectiles charged with high explosives that explode when they strike the armor plate of a ship sometime do comparatively little damage. The search has been for a device to keep the charged shell from bursting until it has passed through the ship's side and has reached a point where it will do great damage. Such an invention is claimed by Hudson Maxim, the foremost inventor of high explosives. And in speaking of it he says: "The offense is bound to win over the defense. We find it so in all history, not only of mechanical automatons, but in inanimate

creations. The active, aggressive animal always has developed ways and means to penetrate the interior of all the armored animals. So it is in warfare. The projectiles of the aggressor smash through the armor plate of the defender."

At Indian Head recent tests have been made with the new invention, and it is claimed that if a 13-inch projectile from one of the big guns of the battleship Maine, charged with high explosives and equipped with the new fuse be fired through the 12-inch side armor of an enemy's ship, it would kill every man in the compartment where it exploded. The effect of the explosion behind the armor would be to rip up the coffer-dam backing and hurl inward fragments of that as well as pieces of the projectile itself in every direction, causing great destruction in that part of the ship. that part of the ship. It would also smash from the side of the ship the entire piece of armor plate which it struck, and if the point was near the water line it would make an opening very dangerous indeed.

The high explosive projectiles employed by foreign countries are not expected to penetrate heavy armor plate and explode behind it, as they are provided with impact fuses, which causes them to burst the instant they strike and in many cases do but little damage to heavyarmy battleships. The advantages of the Maxim safety detonating fuse are safety in handling and explosion after penetration. A detonator, which has to be very powerful, is dangerous unless it is held in a position of safety before firing from the gun. The new fuse is so constructed that it is impossible to explode the bursting. charge of the shell, even should the detonator be set off prematurely. In order to burst the projectile it is necessary that it be fired and strike something, when the fuse will act on the explosive charge at a desired distance of penetration.

Balloon "Stable"

WE

are familiar with stables for horses, garages for automobiles and shelters for other things, but a balloon barn is something of a novelty This photograph illustrates such a barn which has been erected on what is called a "balloon farm" in New York state. As the

photograph shows, the end of the barn is closed with a canvas covering, which can be readily rolled up like a window curtain while the interior is high enough to inflate a balloon or air ship with gas so that it can be prepared for an ascent under cover. The gas is brought to the interior of the barn in pipes, and the balloons are inflated by means of the hose shown in the center of the photograph.

A part of the necessary equipment of the barn is a sewing machine which is used for making repairs to tears in the gas bags.

London's Great Amphitheater

THAT the British expect a vast attend

ance at the Olympic games which are to take place at London in 1908 is evidenced by the size of the amphitheater which is to be built for the purpose.

The amphitheater is to be erected at Shepherd's Bush, a western suburb, and is to provide accommodation for 367,000 spectators-far more than ever assembled to witness any of the Olympic games of ancient Greece, and four times the num

ber accommodated by the Flavian Amphitheater of Rome.

The sloping tiers of seats-seats enough for every inhabitant of Buffalo or Cincinnati-will rise to a great height. The structure will, of course, be roofless.

Renews Placer Mining PLACER mining operations in South

ern California, particularly on the desert side of the coastal mountains, has been a dead industry for a number of years. The principal reason for this has been the lack of available water supply. Mining men throughout the state are looking with much interest on a new invention which is being tried out in the Newhall placer beds, in Los Angeles county.

In this machine the fine gravel, sand, and the free gold fall to the bottom of a conical tank from which the gravel and sand are lifted by an upward current of water through a central tube, leaving the gold at the bottom, where it remains on account of its greater specific gravity.

The gravel is first lifted by means of a bucket chain elevator to the top of the machine, where it passes through a chute to a circular, submerged grizzly within the tank. Here, by means of heavy steel wire brushes extending from arms which revolve slowly around the grizzly, the gravel is thoroughly washed, the coarser material being screened off and passing directly to the tailings stacker.

The rising column of water through the central tube (produced by means of screw propellers) lifts all the light gravel and sand from the tank, depositing it in a solid steel trough between the central tube and the grizzly, where it is carried along by means of steel brushes to the tailings stacker. These brushes extend from the same lateral arms that carry the interior brushes over the grizzly. The gold is left at the bottom of the tank, whence it is easily drawn off by means of a valve.

By these means it has been found that an immense quantity of gold bearing gravel can be handled in a given length of time. Under conditions which were not entirely auspicious, as high as twenty cubic yards of auriferous earth have been

Make Concrete Poles THE latest of the many uses to which

concrete is being put is the making from it of telephone and telegraph poles, and this is of especial importance on account of the scarcity of suitable pine poles. It is claimed that these poles may be used for any purpose for which wood or iron is used, such as trolley poles, block-signal poles, etc.

A skeleton framework of four corrugated iron rods is covered with concrete, the resulting pole being octagonal in shape and tapering gracefully. At the top, mortises are provided for the crossarms, which are fastened by iron bolts. There are also mortises for the use of linemen in climbing.