The substitution of oil for water in cooling cylinders of gasoline engines does away with any risk of damage to the engine by freezing and expansion of the water jacket. Small engines can be cooled with oil by replacing the water tank with an ordinary hot-water heat radiator. For engines of medium size a . special radiator is used in the form of a vertical boiler containing small tubes open at both ends. The top of the boiler is covered by a cone and short stack into which the exhaust from the engine is conducted to induce a draft through the tubing. The hot oil is fed into the top of the boiler and the cooled oil drawn off at the bottom to circulate back through the jacket of the engine. Large engines require the addition of a small centrifugal pump to keep the oil circulating rapidly. This form of cooler has been successfully applied to engines of over 40 h. p. It cannot freeze, requires no attention, and works well under any climatic conditions. The tank, connections and jackets are sealed air tight, so that no waste of the oil can take place, and the original supply will last as long as the engine.

The fourth jewel screw of almost any of the standard American makes of watches is so small that to the naked eye it looks like a mere speck of metal. It must necessarily be perfect in all respects. When examined under a powerful microscope it is seen that the threads averaged 260 to the inch. It is exactly four one-hundredths of an inch in diameter and over 50,-000 could be packed into a lady's thimble with ease. Counting these screws is never attempted, of course, but 100 are weighed on a delicate steelyard and the total number of an output is arrived at by comparing the gross weight with the weight of these. Such tiny screws can only be made in large numbers by machinery, and the operation attending their manufacture is one of the most delicate things in watchmaking.

In boring cylinders it is better to use three cutters than one. With one cutter there is spring to the bar. With two the bar is less well supported than with three. One cutter will cause the hole to be smaller in the middle than at the ends of the cylinder, and the surface of the metal will be rougher in the middle than at the ends of the cylinder.

A boy of 17 is not too young to enter an engineering school, though he could better grasp the requirements of the course were he a year older. It is not the most brilliant or showy student that always makes the best engineer, the chap who has to "dig" and acquire knowledge slowly often developing into the most trustworthy engineer. In its commercial application engineering is the art of making a dollar earn the most interest.

Rocking stones, as they are called, have come into the positions in which they are found usually by one of three methods. Either the stones are practically in situ, and the surrounding rock having been removed by natural decay and disintegration, leaving the stone so peculiarly balanced that it may be readily moved by pressure and caused to rock to and fro; or the rock has fallen from some higher elevation, and some of the stones helping to support it in its new position have disintegrated and disappeared, or the rock hasbeen carried to its present position by ice. All three of these conditions are found, and possibly some others. Some rocking stones weigh many tons.

The young man who, after making up his mind what he wants to do in the world, begins to hunt up obstacles in his path, to magnify them, to brood over them until they become mountains and then to wait for new ones to develop, is not a man to take hold of great enterprises. The man who stops to weigh and consider every possible danger or objections never amounts to anything. He is a small man made for little things. He walks around an obstacle and goes as far as he can easily, but when the going gets hard he stops.

The strong man, the positive, decisive soul who is determined to carry it out, cuts his way to his goal regardless of difficulties. It is the wobbler, the weak, kneed man, the discouraged man, who turns aside, who takes a crooked path to his goal. Men who achieve things, who get things done, do not spend time haggling over perplexities or wondering whether they can overcome them. A penny held close to the eye shuts out the sun. When a man lies down on the ground to see what is ahead of him a rock may hide a mountain. A small man holds petty difficulties so closely in view that great objects beyond are entirely shut out of sight. Great minds keep their minds on the goal. They hold the end so persistently in view and it looks so grand and desirable that the intermediate steps, no matter how perplexing, are of comparatively little importance. The great man asks but one question: " Can the thing be done ?" not " How many difficulties will I run across?" If it is within the reach of possibility all hindrances must be pushed aside.

Influenza has been for some time past very prevalent in Germany, says Richard Guenther, Consul-General, Frankfort, Germany, extending to horses, which are in some instances, quarantined. The Frankfort "News" states that in 1890, when influenza was epidemic throughout Europe, many workmen contracted the disease in three watch factories at Madretsch, and a number died. At one factory at Madretsch, however, the disease did not appear. Investigations showed that oil of turpentine was used in the turning of the metals used for watch cases, and the oil becoming warm, evaporated and the workmen inhaled the air laden with it. This seemed to protect them against the disease. Since then oil of turpentine has been always evaporated in that factory upon a stove, and not a case of influenza has ever occurred there. This preventive measure is successfully employed in dwellings, and the inhaling of water vapor with oil of turpentine.is said to act favorably on the affected respiratory organs.

As disagreeable experiences are had at the mints from time to time with brittle gold alloys, the subject has again been taken up by chemists. Tests have confirmed the fact that lead, iron and tellurium must be avoided, as they act injuriously upon the properties of gold, even in the smallest quantities.

At the Paris mint the first specific investigations concerning this important question were conducted. In 1868 the director of that mint caused elaborate experiments to be made in order to learn what other metal besides silver and copper could be responsible for a deterioration of gold. Brittle coins were collected and their chemical composition was accurately ascertained. It was found that silver and copper are much less deleterious than lead and iron. In some brittle gold coins only one-fifth of 1 per cent of lead or iron was found, but these quantities were sufficient to impair the malleability of the gold.

When a splinter has been driven into the hand it can be extracted by steam. Fill a wide-mouthed bottle nearly full of hot water, place the injured part over the mouth and press it slightly. The suction thus produced will draw the flesh down, and in a minute or two the steam will extract the splinter, also the inflammation.-"National Magazine."

In hard soldering, or brazing with borax, there are one or two little points which cause trouble. The salt forms large bubbles in contact with the soldering iron and easily scales away from the surface of the parts to be soldered. Then, too, the parts must be cleaned each time before applying the borax. Instead of borax use boric acid and sodium carbonate, of which borax is made, and these troubles disappear. The heat of the iron combines them in such a way as to make an excellent flux - free from the difficulties experienced with borax.