The transformer has made long distance the actual achievement that it is. It is this apparatus that brought the mountain to Mohammed. Without it high pressure would be impossible and it is on high pressure that success of long distance transmission depends. To convey electricity to distant centres at a low pressure would require thousands of dollars in copper cables alone as conductors. To illustrate the service of the transformer in electricity it is only necessary to consider water power at a low pressure. In such a case the water can only be transmitted at slow speed and through great openings, like dams or large canals, and withal the force is weak and of little practical efficiency, whereas under high pressure a small quantity can be forced through a small pipe and create an energy beyond comparison to that developed when under low pressure. The transformer raises the voltage and sends the electrical current under high pressure over a small wire and so great is this pressure that thousands of horse-power can be sent to great distances over small wires with very little loss. Water power is now changed to electrical power and transmitted over slender copper wires to the great manufacturing centres of our country to turn the wheels of industry and give employment to thousands. Nearly one hundred cities in the United States alone are today using electricity supplied by transmitted water-power. Ten years ago Niagara Falls were regarded only as a great natural curiosity of interest only to the sightseer, today those Falls distribute over 100,000 horse-power to Buffalo, Syracuse, Rochester, Toronto and several smaller cities and towns. Wild Niagara has at last indeed been harnessed to the servitude of man. Spier Falls north of Saratoga, practically unheard of before, is now supplying electricity to the industrial communities of Schenectady, Troy, Amsterdam, Albany and half a dozen or so smaller towns. Rivers and dams, lakes and falls in all parts of the country are being utilized to supply energy, though at the present time only about one-fortieth of the horse-power available through this agent is being made productive. The water conditions of the United States are so favorable that 200,000,000 horse-power could be easily developed, but as it is we have barely enough harnessed to supply 5 million horse-power. Eighty per cent. of the power used at the present time is produced from fuel. This percentage is sure to decrease in the future for fuel will become scarcer and the high cost will drive fuel power altogether out of the market. New York State has the largest water power development in the Union, the total being 885,862 horsepower; this fact is chiefly owing to the energy developed by Niagara. The second State in water-power development is California, the total development being 466,774 horsepower over 1,070 wheels or a unit installation of about 436 H.P.