_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 suspended 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.