NO END OF AMUSEMENT MAY BE AF DUST BY FERTILIZING THE SAWDUST

FORDED BY RAISING PLANTS IN SAW WITH A CHEMICAL SOLUTION.

BEGINNING AN EGGSHELL GARDEN

NUTRIENT chemical solutions

are commonly used in all biological laboratories. Probably the most popular one of the kind is that invented by Professor Julius Von Sachs, and supplied in tablet form by the Arcadia laboratory at Sound Beach, Connecticut. By the aid of these nourishing tablets plants may be grown in all sorts of unpromising situations and with few roots, because the plant seems soon to learn that when chemicals are provided it does not need to develop ramifying roots to search through the soil for the chemical constituents that are needed for its growth.

One of the most popular methods of experimenting, especially by children and by nature study teachers, has been the growing of a variety of plants from sawdust in eggshells. Holes about an inch in diameter should be made in a

board or a plank, and in them

the eggshells should be placed after a tiny opening has been punched in the bottom of each shell. The board should be placed over a pan or some similar receptacle to catch the drainage. Plant the seeds in the moistened sawdust and keep them in a warm place. When the plants begin to grow, wet the sawdust with the solution either from the original supply or from the drippings. Among the plants giving most satisfactory results by this method may be mentioned, perhaps first of all as the choice of the writer, white lupine, sunflower, oats, Indian corn. For a decorative climber the hairy vetch has been found to be very satisfactory.

Six tablets should be moistened, and when soft should be crushed and stirred in a quart of water. With the milky fluid feed the young plants. It may be used until they reach maturity. Plants may be grown by this method directly in the solution or on wire netting suspended over the solution, or in crushed stone, beads, bits

POPULAR SCIENCE

THE CZAR OF CANNONS

WHAT is declared to be the largest

cannon ever cast is that to be seen in the Kremlin Square at Moscow. It goes by the name of the Czar of Cannons. It weighs 2,400 puds and dates from the reign of Feodor Ivanovitch. Its cannon balls weigh 120 puds. A pud is a Russian measure of weight equal to about thirty-six pounds.

FISH

DOCTORING

FISH doctoring is now going on in all the large aquariums all over the world.

For example, it is now known that the diseased fresh-water fish derives marked benefit from a brief stay in salt water and vice versa. Such treatment, however, does. not always suffice.

At times a surgical operation becomes necessary as in the case of a very bad growth of fungus about the gills. The fish which has been previously placed in the operating tank is carefully lifted out with a net. The surgeon then grasps the patient firmly with his left hand and with the scalpel removes the foreign substance. Abscesses are also lanced, but it is seldom that this proves successful and is only resorted to in extreme cases. We must here realize that a fish is a creature of the water. It is impossible for it to sustain life in the

MOST POWERFUL BIRD OF PREY. The harpy eagle, recently received at the New York Zoological Gardens from South America. This bird has been known to carry off sheep and young pigs. There are said to be but two species of this crea ture in captivity in the world.

105

air for more than a limited period of time. Just as soon as it is removed from its natural element, it begins slowly to die.

The operations most frequently successful are performed upon fish whose air bladders fail to effect their proper functions. The chief cause of such defects is the too rapid removal of a fish from the water to the air as when it is captured, or removed from one tank to another. Its air bladder is charged to a greater or less extent with water which enables it to maintain its specific gravity in water, but the suddenness with which the fish is jerked out of its natural element prevents it from correctly adjusting the quantities of air and water in the bladder and congestion results.

Moscow.

When returned to its tank, the wretched creature is unable to sink or rise at will and is washed about helplessly. Fishes injured in this way can often be cured by a little massaging. The operator grasps the fish firmly with the left hand by the tail, draws it carefully out of the water up an inclined board reaching into the tank, but allowing the head and shoulders to remain submerged. Massage is then commenced toward the gills and generally after a few minutes' action of the hand, the air

CHARLES DICKENS' CHALET, IN WHICH THE GREAT NOVELIST DID MUCH OF HIS WRITING. Formerly at Gads Hill, Kent. it has been removed to Cobham Hall, Kent.

THE MOST POWERFUL FIRE-FIGHTING MACHINE IN THE WORLD.

The new 126 horsepower giant gasoline fire auto, which travels 35 miles an hour and pumps 744 gallons a minute. has just been placed in commission in New York, and is the first of its kind. The New York fire department expects to have 150 motor driven fire apparatus by the end of 1912. It is the most expensive fire-fighting apparatus in the world.

is successfully forced from the bladder. It must be stated that a convalescent

SIGNAL TOWER REGULATES STREET TRAFFIC

ASERIES of signal towers combined

with a semaphore system is used to regulate street car traffic on the crowded corners of Los Angeles. The tower is in the shape of a box, with windows on all sides and made large enough to hold a man comfortably. As it is set on an iron post with the base of the box ten feet above the curb, it does not obstruct the sidewalk any more than a lamp post.

These towers are placed at corners where car tracks intersect, and they are especially useful at the corners where the street has a "jog" so that the intersection is made on a curve. The watchman on the tower operates semaphores which are in some cases set on top of the tower and in other cases set across the street, wherever it is more convenient

for the approaching

motorman to see them.