Pole vault

“ Whether in practice or in competition, and no matter what height the bar may be, always measure your pole before vaulting. This is done by stepping up to the posts and holding the pole upright until it touches the bar. Let it fall back then, and grasp it with the lower hand one foot below the point where it touched the cross-piece. For a vaulter who takes off with the left foot, the lower hand is the left hand. For a man who takes off with the right foot, it is just the other way. ”

“ The vaulter then runs towards the bar at full speed, plants the spiked end of the pole in the ground about 18 in. in front of the bar and springs into the air, grasping the pole firmly as he rises. As he nears the bar he throws his legs forward, and, pushing with shoulders and arms, clears it, letting the pole fall backwards. In Great Britain the vaulter is allowed to climb the pole when it is at the perpendicular. Tom Ray, of Ulverston in Lancashire, who was champion of the world in 1887, was able to gain several feet in this manner. In the United States climbing is not allowed. ”

“ When he came to the huge steel door of the vault, he stopped and looked within. The floor immediately before him had raised up to form a wall. Beneath it was a round hole that acted as the entrance to a large, metallic, and greasy tube.
Down that funnel had slid the entire population, screaming, wailing, weeping, clutching at one another for support, striking out in a burst of maniacal fury. ”

“ Fig. 15.—External View of Electric Railway Motor mounted upon Car-Wheel Axle.
To enable the motor to give a strong torque and run at a slow speed the number of poles in the field and armature is increased. The design of Fig. 10 has two poles in the field and two in the armature, and is what is known as the bipolar type. Machines having more than two poles in each part are called multipolar machines. The number of poles can be increased by pairs, but not by a single pole—that is, we can have four, six, eight, or any other even number of poles, but not five, seven, or any odd number. ”

“ There is nothing now to indicate that the provision of a vault had been intended by the original builders of these walls. This deficiency was met by the insertion of vaulting shafts and the addition of external buttressing; for as the pressure of the flat wooden roof was exerted for the most part vertically upon its supports, that of the vault would be a strong lateral thrust as well as vertical pressure, and these were to be provided for. ”

“ The fluted dome over room A is bracketed across the corners of the rectangular substructure (Fig. 88) . In several cases where a barrel vault terminates not against a head wall, but against another section of barrel vault, it is adjusted to the angles of the substructure{154} by means of squinch arches (Fig. 99) . A noticeable feature of the vault construction of Ukheiḍir is the presence of masonry tubes running between the parallel barrel vaults (Fig. 100) . ”

“ The weight of the attic wall tends, indeed, in some measure to neutralize the force of the vault thrust, but this is not enough to render the structure secure, and unless the order were effectively steadied by some extraneous means the attic load would constitute a source of danger, as with any disturbance of its equilibrium by thrust its weight would hasten the overthrow of the system. ”

“ But in so confined a space it would, in a short time, necessarily become foul, and unfit for use from frequent contact with the lungs. It was then ejected by a small valve at the bottom of the car;—the dense air readily sinking into the thinner atmosphere below. To avoid the inconvenience of making a total vacuum at any moment within the chamber, this purification was never accomplished all at one, but in a gradual manner,—the valve being opened only for a few seconds, then closed again, until one or two strokes from the pump of the condenser had supplied the place of the atmosphere ejected. ”

“ The simplest kind of vault is that known as the barrel, wagon Or tunnel vault, which is generally semicircular in section, and may be regarded as a continuous arch, the length of which is in excess of its diameter; like the arch (q.v.) , the same provision is required as regards its temporary support whilst the voussoirs constituting one of its rings are being placed in position, for until the upper voussoir, or keystone, is introduced it is not self-supporting. ”

“ The extending ends of the spokes are used to propel the wheel. Four children can ride in the wheel at one time.—Contributed by Maurice Baudier, New Orleans, La.
[162]
A Merry-Go-Round Pole
An inexpensive merry-go-round can be made of a single pole set in the ground where there is sufficient vacant space for the turning of the ropes. The pole may be of gas pipe or wood, long enough to extend about 12 ft. above the ground. An iron wheel is attached on the upper end so that it will revolve easily on an axle, which may be an iron pin driven into the post. ”

“ The vibratory storm that we so narrowly escaped was not due to barometric depression, but came as a responsive consequence of this surcharged area. When that wire ladder was finally cut off and fell; when it reached a certain position; when one end touched the negative, the other the positive pole, then the current became completed and this gigantic battery was discharged. Had we not been rising at the rate of a hundred feet a second we should have been fused after the fashion of the inhabitants of this ghastly territory. ”

“ VAULT [1] (Fr. voute, Ital. volta, Ger. Gavolbe) , in architecture, the term given to the covering over of a space with stone or brick in arched form, the component parts of which exert a thrust and necessitate a counter resistance. In the case of vaults built under the level of the ground, the latter gave all that was required, but, when raised aloft, various expedients had to be employed, such as great thickness of walls in the case of barrel or continuous vaults, and cross walls or buttresses when intersecting vaults were employed. ”

“ The harder the multitude pulled, so long as they remained200 evenly distributed about the circle, the more rigid the pole would become. But if, on the other hand, all the men were to stop pulling and slacken the ropes, the pole would at once fall over. The pole, under such circumstances, would represent the axis of the revolving wheel, which acquired increased stability in exact proportion to the increased velocity of its revolutions, and therefore of the increased force with which its particles tend to fly off into space. ”

“ Alongside the tracks on which stand the trains that are to be broken up and from which the sidings diverge subsidiary tracks are provided for the use of the shunting engines. These engines have a pole projecting horizontally in front of them, or are attached to a “pole-car” having such a pole. The method of working is for the pole to be swung out behind a number of wagons; one engine is then started and with its pole pushes the wagons in front of it until their speed is sufficient to carry them over the points, where they are diverted into any desired siding. ”

“ The pole changer, which is an instrument used by telephone companies for the purpose of calling up their subscribers, consists of a lever which vibrates back and forth by the aid of a flat spring, to which it is attached in much the same manner as the pendulum of an old-fashinoned clock is connected with the spring upon which it swings. There is also a flat piece of metal which is attached to the armature, and stands vertically when the instrument lies upon the table, and which has apparently a certain torsional action ”

“ That is, the commutating pole insures sparkless commutation from no load to heavy overloads with a fixed brush position. Brush shifting devices are not furnished on commutating pole converters. Commutating pole rotary converters for railway service are normally arranged for automatic compounding which is effected by the proper combination of series excitation and inductance between the generator and the rotary converter. This inductance is normally included in the transformer but in special cases may be partly in a transformer and partly in a separate reactance. ”

“ An engine of 2-man power, with an altitude from the ground to the top of the column of 4 feet, and with a fly-wheel measuring 2 feet 6 inches in diameter, is amply sufficient for every purpose. It works evenly and without noise; it is absolutely free from danger, and it is placed instantly in or out of action by merely igniting or extinguishing a single gas jet. But it is remarkable that no one seems to have suggested—even before the gas-engine era—that a “fly-wheel” with a pulley would obviate the old difficulty of the unsatisfactory rotation of the Plate machine. ”

“ In general, to keep the leakage small, the pole cores should be short, and of minimum surface, the pole shoes should not have too wide a span nor be too thick, nor present needless corners, and the axial length of the pole face and of the armature core should not be too great in proportion to the diameter of the working face. ”

“ Independent examiners reported that the Herland pole-engine did forty-eight millions of duty, under various pressures of steam, up to 120 lbs. to the inch, working five-sixths of the stroke expansively, with a speed of twenty strokes a minute, or double the speed of the Watt engine; and the importance of those facts deserves the scrutiny and close study of youthful engineers. ”

“ Do you know that if that vault is taken by either an electric-arc or an oxy-acetylene blow-pipe, I will be suspected?”
“I didn’t think of that.”
“It is a fact! You see the police and the private agencies know a man by his work. How can we take that vault in a new way? How can I go through three layers of vanadium steel?” ”

“ The Canadian pole system, which is largely in use in oil-field operations, is, like the first-mentioned method of drilling, of the percussion type, the chief essential difference being that, instead of a cable connecting the tools to the surface, poles are used. ”

“ In principle the safety-valve denotes an orifice closed by an accurately-fitting plug, which is pressed against its seat on the boiler top by a weighted lever, or by a spring. As soon as the steam pressure on the face of the plug exceeds the counteracting force [Pg 33] of the weight or spring, the plug rises, and steam escapes until equilibrium of the opposing forces is restored.
On stationary engines a lever safety-valve is commonly employed (Fig. 11) . The blowing-off point can be varied by shifting the weight along the arm so as to give it a greater or less leverage. ”

“ If a train parts, or if the air leaks out of the train-pipe, the brakes go on. This automatic principle is a vital one in most safety appliances, and it is secured in the case of the air-brake by one of the most ingenious little devices that man ever contrived, that is, the triple valve, which is placed in the piping system between the brake-cylinder and the car-reservoir. This triple valve has passages to the brake-cylinder, to the car-reservoir, to the train-pipe, and to the atmosphere. ”

“ These poles are very carefully made of wood and are only about an inch in diameter. Every second pole is guyed with a wire and braced with a pole. The poles are painted in black and white stripes to make them conspicuous and to prevent people from running over them. The German practice is to lay these wires and abandon them when they are no longer needed. The British, on the contrary, make it a point of honor to recover all their poles and wire. In the retreat from Mons their signal corps had such heavy losses in attempting to do this that they were seriously hampered by lack of personnel. ”

“ The Wheal Prosper 16-inch pole high-pressure expansive steam vacuum engine commenced its up-stroke with steam of 100 lbs. on the inch, acting on the 122 square inches of the pole, which steam at the finish of the stroke was reduced by expansion to 10 lbs., giving, say, an average steam pressure of 55 lbs. The down-stroke was caused by a vacuum under the pole of 14 lbs. on the inch, reduced by, say, one-third loss in working the air-pump to 9 lbs., giving from the compound stroke a force of 64 lbs. on each square inch, which, multiplied by the area of the pole, gives a net force of 7808 lbs. ”

“ Upon stopping the engine, and extinguishing the fire, it is found that the steam condensed within the boiler produces a vacuum; so that the atmosphere, pressing on the external surface of the boiler, has a tendency to crush it. To prevent this, a safety valve is provided, which opens inwards, and which being forced open by the atmospheric pressure when a vacuum is produced within, the air rushes in, and a balance is obtained between the pressures within and without. ”

“ The specification states:
'The transportation of coal, and all other heavy articles in lumps, has been attended with great injury to the cars, requiring the bodies to be constructed with great strength to resist the outward pressure on the sides, as well as the vertical pressure on the bottom, due not only to the weight of the mass, but the mobility of the lumps among each other tending to 'pack,' as it is technically termed. Experience has shown that cars, on the old mode of construction, cannot be made to carry a load greater than its own weight ”