electricity from elevated points" for telegraphic purposes, based on the principle mentioned, and made successful experiments on the Blue Ridge mountains in Virginia near Washington, accounts of which were published in Washington papers at the time; but being poor and receiving no aid or encouragement he was compelled to give it up. Marconi of Italy has been more successful in this direction, and has sent electric messages and signals from high stations over the English Channel from the shores of France to England. So that now wireless telegraphy is an established fact.

It is certainly thrilling to realize that there is a mysterious, silent, invisible and powerful mechanical agent on every side of us, waiting to do our bidding, and to lend a hand in every field of human labour, and yet unable to be so used without excitement to action and direction in its course by some master, intermediate between itself and man. The principal masters for this purpose are steam and water power. A small portion of the power of the resistless Niagara has been taken, diverted to turn the machinery which excites electricity to action, and this energy in turn employed to operate a multitude of the most powerful motors and machines of many descriptions.

So great is the might of this willing agent that at a single turn of the hand of man it rushes forth to do work for him far exceeding in wonder and extent any labour of the gods of mythological renown.

CHAPTER X.

HOISTING, CONVEYING AND STORING.

ALLUSION has been made to the stupendous buildings and works of the ancients and of the middle ages; the immense multitude of workers and great extent of time and labour employed in their construction; and how the awful drudgery involved in such undertakings was relieved by the invention of modern engineering devices-the cranes, the derricks, and the steam giants to operate them, so that vast loads which required large numbers of men and beasts to move, and long periods of time in which to move them, can now be lifted with ease and carried to great heights and distances in a few minutes by the hands of one or of a few men.

But outside of the line of such undertakings there is an immense field of labor-saving appliances adapted for use in transportation of smaller loads from place to place, within and without buildings, and for carrying people and freight from the lower to the upper stories of tall structures. In fact the tall buildings which we see now in almost every great city towering cloudward from the ground to the height of fifteen, twenty and twenty-five stories, would have been extravagant and useless had not the invention of the modern elevator rendered their highest parts as easy of access as their lowest, and at the same time given to the air space above the city

lot as great a commercial value in feet and inches as the stretch of earth itself.

Many of the "sky-scrapers " so called, are splendid monuments of the latest inventions of the century. It is by means of the modern elevator that the business of a whole town may be transacted under a single roof.

In the multiplicity of modern human contrivances by which the sweat and drudgery of life are saved, and time economised for worthier objects, we are apt to overlook the painful and laborious steps by which they were reached, and to regard with impatience, or at least with indifference, the story of their evolution; and yet no correct or profound knowledge of the growth of humanity to its higher planes can be obtained without noting to what extent the minor inventions, as well as the startling ones, have aided the upward progress.

For instance, consider how few and comparatively awkward were the mechanical means before this century. The innumerable army of men when men were slaves, and when blood and muscle and brain were cheap, who, labouring with the beast, toiled upward for years on inclined ways to lay the stones of the stupendous pyramids, still had their counterpart centuries later in the stream of men carrying on their shoulders the loads of grain and other freight and burdens from the shore to the holds of vessels, from vessels to the shore, from the ground to high buildings and from one part of great warehouses to another. Now look at a vessel moved to a wharf, capable of holding fifty thousand or one hundred thousand bushels of grain and having that amount poured into it in three hours from the spouts of an elevator, to which the grain has been carried in a

myriad buckets on a chain by steam power in about the same time; or to those arrangements of carriers, travelling on ropes, cords, wires, or cables, by which materials are quickly conveyed from one part of some structure or place to another, as hay and grain in barns or mows, ores from mines to cars, merchandise of all kinds from one part of a great store to another; or shot through pipes underground from one section of a city or town to their destination by a current of air.

True, as it has before been stated, the ancients and later generations had the wedge, the pulley, the inclined plane, the screw and the windlass, and by these powers, modified in form and increased in size as the occasion demanded, in the form of cranes, derricks, and operated by animal power, materials were lifted and transported; but down to the time of the practical and successful application of steam by Watt in the latter part of the 18th century, and until a much later period in most places in the world, these simple means actuated alone by men or animals were the best means employed for elevating and conveying loads, and even they were employed to a comparatively limited extent.

The century was well started before it was common to employ cups on elevator bands in mills, invented by Oliver Evans in 1780, to carry grain to the top of the mill, from whence it was to fall by gravity to the grinding and flouring apparatus below. It was not until 1795 that that powerful modern apparatus the hydraulic, or hydrostatic, press was patented by Bramah in England. The model he then made is now in the museum of the Commissioner of Patents, London. In this a reservoir for water is provided, on which is placed a pump having a piston

rod worked by a hand lever. The water is conveyed from the reservoir to a cylinder by a pipe, and this cylinder is provided with a piston carrying at its top a table, which rises between guides. The load to be carried is placed on this table, and as the machine was at first designed to compress materials the load is pressed by the rising table against an upper stationary plate. The elevation of the table is proportionate to the quantity of water injected, and the power proportionate to the receptive areas of the pump and the cylinder. The first great application of machines built on this principle was by Robert Stephenson in the elevation of the gigantic tubes for the tubular bridge across the Menai straits, already described in the chapter on Civil Engineering. The century was half through with before it was proposed to use water and steam for passenger elevators. In 1852 J. T. Slade in England patented a device consisting of a drum to be actuated by steam, water, or compressed air, around which drum ropes were wound, and to which ropes were attached separate cages in separate wells, to counterbalance each other, the cages moving in guides, and provided with brakes and levers to stop and control the cages and the movement of the drum. Louis T. Van Elvean, also of England, in 1858 invented counterbalance weights for such lifts. Otis, an American, invented and patented in America and England in 1859 the first approach to the modern passenger elevator for hotels, warehouses, and other structures. The motive power was preferably a steam engine; and the elevating means was a large screw placed vertically and made to revolve by suitable gearing, and a cylinder to which the car was attached, having projections to work in the threads of the screw.