This was four years after the Civil War, but its effects were felt everywhere, and notably in the depreciation of government securities and our paper money. Gold, being the standard, was regarded as much more valuable than a paper promise to pay issued by a government heavily in debt. A gold dollar, therefore, would buy much more than a paper dollar, at times a dollar and a quarter, or a dollar and a half in value. In a word, gold commanded a high premium. For several years afterward there was a great deal of speculation in the precious metal, and a "Gold Room" had been established in Wall Street, where the transactions took place. At first the prices were exhibited on a blackboard there, but before long this plan was found to be too slow for the brokers. Then Dr. S. S. Laws, vice president and presiding officer of the Gold Exchange, invented a system of indicators to be placed in the offices of brokers. These indicators were operated from a complicated transmitting instrument at the Exchange, and each one showed the fluctuations of price as transactions took place. Dr. Laws resigned from the Exchange and organized the Gold Indicator Company, which put the system into operation. At the time when Edison took shelter at night in the battery-room of the company there were about three hundred instruments in the offices of subscribers. While waiting to hear from the Western Union, Edison spent his days studying the indicators and the complicated transmitting instrument in the office, controlled from the keyboard of the operator on the floor of the Gold Exchange.