phrey, Hoffman, Sherman, Jefferson, Grant, McClellan, Franklin, and Jackson.

At the center of the reef the highest tunnel was known as Grant Heading. Nine feet of rock was left to form a roof. The rock was not very hard, but full of seams and fissures, through which the water constantly dripped. The narrow seams were closed by blocking, and when a wide seam was struck it had to be closed outside.

In one case the miners came upon a horizontal seam, through which the water poured at the rate of six hundred gallons a minute, and before the flow could be stopped, the miners were standing in three or four feet of water. Bags of clay were kept in readiness on the edge of the coffer-dam, over each heading, so that, whenever a seam was found, it could be closed as quickly as possible.

A large number of men were employed in these headings, drilling holes in the rock, and preparing for the great blast to For a long time, hand drills only were used, but the work was greatly facilitated by the introduction of drills operated by means of compressed air.

It was not until September, 1876, that the rocks of the reef were completely "honey-combed." The process left a roof of rock, supported by piers, which were so perforated as to secure their destruction by the blast. The quantities of explosive materials, finally decided upon by General Newton and his engineers, were estimated as follows:-Dynamite, 25,976 pounds; Vulcan powder, 14,244 pounds; Rend Rock, 9,061 pounds; Dynamite in Primers, 3,500 pounds. Dynamite is simply nitroglycerine mixed with sand, and the Vulcan and Rend Rock are brands of strongest blasting powder. Connected with the explosive material in each of the sealed canisters was a copper wire, and all these wires were connected with the coil attached to twenty-three powerful electric batteries. Thus, the batteries were connected with each canister, and operated upon each, while each canister was connected with and operated upon all the others. To make all these connections, about twenty-three iniles of wire was used. The excavations in the rock were

896

THE GREAT EXPLOSION.

filled with water. It required 47,561 cubic yards to fill them. The water was let in at the rate of 2,000 cubic yards per hour, completing the filling at eight o'clock, Saturday evening, September 23d. Three hundred feet from the rock, General Newton had constructed a bomb-proof building, twelve feet square, in which he placed the batteries. The metallic plates were not submerged in the acids till noon of the next day (Sunday), so that the electricity could not be generated till near the time of the explosion, which had been fixed at 2:50 p. m. Guard boats were stationed on the river to force a suspension of navigation, and the police took up a line along the river front to guard against a too near encroachment by sight-seers. At 2:25 p.m. the first signal gun was fired, and, ten minutes later, a second gun announced the near approach of the dreaded hour. The assembled multitude awaited with breathless interest the last and most important scene in the Hellgate drama. Men and women stood, watches in hand, counting the minutes and seconds, or gazing anxiously across the water to where the great upheaval was to take place. All waited in anxious suspense, and finally, at exactly the appointed time, the tiny finger of little Mary Newton, three years old, guided by the firm hand of her father, pressed the magic key, the shock came, away went Hallett's Point reef, and the fears of the timid were found to have been totally groundless. The shock was merely a dull, deadened sound, as of distant thunder, and the upheaval was less than might naturally have been expected from firing such an amount of explosives. The water rose up like a wall of many geysers to a height of from sixty to seventy feet. It appeared snow-white, and formed of huge cones which had dome-like terminations. There was so much spray between these cones, however, that the appearance of the water was that of a wall from which great columns stood out in high relief. Suddenly there came out from the eastward a dark cloud of mingled stones and earth, in front of which were huge wooden fragments of the coffer-dam. The roof of the mine seemed to rise to the surface, and then slowly sink to the bed of the river. The water, after receding, was black and discolored, and, after

GENERAL NEWTON'S TRIUMPH.

897

seething and boiling for a few seconds, apparently resumed its natural state. The concussion was slight, and crowds of people remained, in the vain expectation of witnessing something which would be on a more magnificent scale.

It was feared that the blasted rocks would pile up around the sides of the excavation, and form a dangerous temporary obstruction. As a precaution, three massive spar buoys were held in readiness to mark the locality until the work of sounding was finished, and the position of the débris discovered. The United States steamer Cactus on the afternoon of Monday, the 25th, began the work of laying out the buoys. The first sounding was made at a distance of two hundred feet from shore, along an arc around Hallett's Point and over the exploded mine. Tour after tour was made at greater distances from shore, and with the shaft deeper in the water. Not a rock or obstacle of any kind was encountered during the afternoon. In referring to the record of water found at the different soundings, the number of feet reported may be considered the amount of water at mean or average low tide. When the work of excavation began, the tide-gauge showed four feet of water over the average low water mark. The trial-shaft made the tour unhindered at a depth of sixteen feet, thus demonstrating a safe passage for vessels of such a draft at a point where the day before a giant rock protruded from the water. The last trial was made at three hundred and fifty feet out, and showed a depth of twentyone feet at low water.

General John Newton may be said to have achieved a victory greater than any in war. The 24th of September ought hereafter to be celebrated as the jubilee day of commerce, and the anniversary of the greatest triumph of engineering science in history. The seven years' toil on Hallett's Point Reef at Hellgate has culminated in a grand coup de maître, which was successful in every detail and in the full accomplishment of all the results expected, and all without a single disaster to human life. Begun upon a carefully matured plan-carried on with the quiet, painstaking persistence of science-the long labor of demolishing the great obstacle to navigation has at last been completed.

THE EARLY HISTORY OF MANKIND.

THE STONE AGE. PICTURE OF ADAM AND EVE. — HOW EVE CUT T -MINERS OF ANCIENT TIMES. DISCOVERY OF STONE IMPLEMEN INVENTION OF FIRE. - HOW GOLD WAS FOUND. — COPPER AND E THE BRONZE AGE. IRON AND ITS USES. MINERAL PRODUC

DIFFERENT COUNTRIES.- QUICKSILVER IN SPAIN AND CALIFORN WEALTH OF NEVADA. ROMANTIC STORY OF THE COMSTOCK MINERAL FUTURE OF AMERICA.

THE most extensively worked mineral substance present day is coal, yet it is the most recent of mine coveries. Iron, copper, tin, and nearly all the metal dug from the earth, and used long before the value of coal was known.

In the earliest days of mankind, tools for various use made of wood, bones, or stone. The first tools were un edly of wood, but the material was so perishable in its that no specimens from those early days have come down Stone, being a harder substance than wood, and much durable in its character, rapidly took its place. The when the human race was in its infancy has been pr classified as the "Age of Stone," for the reason that i that time was ignorant of the use of metal. Many imple from the stone age have come down to us, and are for various parts of the world. In the copper mines on the of Lake Superior, many tools have been found which were by a race long extinct, and of which we have no history

In opening one of these mines, several years ago, more a hundred stone axes and wedges were discovered large mass of native copper, which had been moved a distance, and supported upon sticks of timber.

DISCOVERY OF FIRE.

899

No implements other than those of stone were found, and all of these had been broken in an unsuccessful attempt to cut the mass of copper in two. In various parts of America, Europe, and Asia, stone implements from the early days of the human race are found, and at the present time there are many savage tribes belonging practically to the stone age.

In some islands of the Pacific the people have not yet emerged from what is to us a very remote period. Barbarism under some circumstances may almost be considered perpetual. The history of the early days of mankind upon the earth is very largely a matter of conjecture: much of it comes from tradition, and much of it from calculation. The great antiquity of the human race is a recognized fact, and geologists have shown that the period of early barbarism may have extended over tens of thousands of years. Civilization, properly speaking, began only with the discovery of fire and metals.

Some of the Greek mythologists say that Prometheus stole fire from heaven. The more prosaic fact is, that fire was first discovered by means of lightning, which set fire to the forests, and thus revealed to mankind a new element in nature. It is probable that our first parents in the garden of Eden had no knowledge whatever of this element, or of the metals, or even of implements of wood or stone. Consequently the enthusiastic artist of the middle age, who drew a picture of Adam and Eve standing in front of a fire to warm themselves, and represented Eve holding a knife in her hand, with which she was cutting slices from the fatal apple to give to the waiting Adam, was guilty of anachronism.

There are other conjectures of the discovery of fire, but they are purely conjectures. Fire may have been known from the earliest ages, through volcanic eruptions and streams of lava.

People who lived far away from volcanos may have discovered it from the spontaneous combustion of wood after hot and dry summers, or of masses of weeds and rubbish thrown together, and forming peculiar chemical combinations. It is possible that other people may have discovered fire by means