ballots, the prevention of fraudulent deposition of ballots, the automatic correct counting of the same, and a display of the result as soon as the balloting is closed.

Successful electrical devices have been made for recording the votes of a great number of persons in a large assembly by the touch of an aye or "nay" button at the seat of the voter and the recording of the same on paper at a central desk.

The invention and extensive use of bicycles, automobiles, etc., have given rise to the invention of cyclometers, which are small devices connected to some part of the vehicle to indicate to the rider or driver the rate at which he is riding, and the number of miles ridden.

Speed Indicators.-Many municipalities having adopted ordinances limiting the rate of speed for street and steam cars, bicycles, automobiles, and other vehicles, a want was created, which has been met, for devices to indicate to the passengers, drivers or conductors the rate at which the vehicle is travelling, and to sound an alarm in case of excess of speed, so that brakes can be applied and the speed reduced. Or to relieve persons of anxiety and trouble in this respect, ingenious devices have been contrived which automatically reduce the speed when the prescribed limit has been exceeded.

Weighing Scales and Machines.-"Just balances and just weights" have been required from the day of the declaration, "a false weight is an abomination unto the Lord." And therefore strict accuracy must always be the measure of merit of a weighing machine. To this standard the inventions of the century in weighing scales have come. Until this century the ordinary balance with equal even arms sus

pended from a central point, and each carrying means for suspending articles to be weighed, or compared in weights, and the later steelyard with its unequal arms, with its graduated long arms and a sliding weight and holding pan, were the principal forms of weighing machines. Platform scales were described in an English patent to one Salman in 1796, but their use is not recorded. The compound lever scale on the principle of the steelyard, but arranged to be used with a platform, was invented and came into use in the United States about 1831. Thaddeus and Erastus Fairbanks of St. Johnsbury, Vermont, were the inventors, and it was found to meet the want of farmers in weighing hemp, hay, etc., by more convenient means than the ordinary steelyard. They converted the steelyard into platform scales. The leading characteristics of such machines are, first, a convenient platform nicely balanced on knife edges of steel levers, and second, a graduated horizontal beam, a sliding weight thereon connected by an upright rod at one end to the beam, and at its opposite end to the balance frame beneath the platform.

The modification in size and adaptation of this machine for the weighing of different commodities amounted to some 400 different varieties-running from the delicately-constructed apparatus for weighing the fraction of a grain, to the ponderous machines for weighing and recording the loaded freight car of fifty or sixty tons, or the canal-boat or other vessel with its load of five or six hundred tons. The adaptation of a balance platform on which to place a light load, or to drive thereon with heavy loads, whether of horses, steam, or water vehicles, was a great blessing to mankind. No wonder that they were soon sold

all over the world, and that monarchs and people hastened to heap honors on the inventors.

Spring weighing scales have recently been invented, which will accurately and automatically show not only the weight but the total price of the goods weighed, the price per unit being known and fixed.

In the weighing of large masses of coarse material, such as grain, coal, cotton seed, and the like, machines have been constructed which automatically weigh such materials and at the same time register the weight.

Previous to this century no method was known, except the exercise of good judgment in the light of experience, of accurately testing the strength of materials. Wood and metals were used in unnecessarily cumbrous forms for the purpose to which they were put, in order to ensure safety, or else the strength of the parts failed where it was most needed.

The idea of testing the tensile, transverse, and cubical resisting strength of materials has been applied to many other objects than beams and bars of wood and metals; to belts, cloths, cables, wires, fibres, paper, twine, yarn, cement, and to liquids. Kiraldy, Kennedy, and others of England, Thomasset of France, Riehle of Germany, and Fairbanks, Thurston and Emery of the United States, are among the noted inventors of such machines.

In the Emery system of machines, consisting of scales, gages, and dynamometers, the power exerted on the material tested is transmitted from the load to an indicating device by means of liquid acting on diaphrams. The same principle is employed in his weighing machines.

By one of these hydraulic testing machines the tensile strength of forged links has been ascertained by the exertion of a power amounting to over 700,000 pounds before breaking a link, the chain breaking with a loud report.

The most delicate materials are tested by the same machine the tensile strength of a horsehair, some of which are found to stand the strain of one and two pounds. Eggs and nuts are cracked without being crushed, and the power exerted and the strain endured automatically recorded. Steel beams and rods have been subjected to a strain of a million pounds before breaking.

Governments, municipalities, and the people generally are thus provided with means by which they can proceed with the greatest confidence in the safe and economical construction and completion of their buildings and public works.

CHAPTER XXVI.

MUSIC, ACOUSTICS, OPTICS, FINE ARTS.

NEITHER the historic nor prehistoric records find man without musical instruments of some sort. They are as old as religion, and have been found wherever evidence of religious rites of any description have been found, as they constituted part of the instrumentalities of such rites. They are found as relics of worship and the dance, ages after the worshippers and the dancers have become part of the earth's strata. They have been found wherever the earliest civilisations have been discovered; and they appear to have been regarded as desirable and necessary as the weapons and the labour implements of those civilisations. They abounded in China, in India, and in Egypt before the lyre of Apollo was invented, or the charming harp of Orpheus was conceived.

There was little melody according to modern standards, but the musical instruments, like all other inventions, the fruit of the brain of man, were slowly evolved as he wanted them, and to meet the conditions surrounding him.

There were the conch shell trumpet, the stone, bone, wood and metal dance rattles, the beaks of birds, and the horns and teeth of beasts, for the same rattling purpose. The simple reed pipes, the hollow wooden drums, the skin drum-heads, the stretched strings of fibre and of tendons, the flutes, the harps, the guitars,