In May 1899, Tesla, several of his assistants, and a local contractor commenced the construction of Tesla's laboratory shortly after arriving in Colorado Springs, a high-altitude location where he would have more room than in his downtown New York City laboratory for his high-voltage, high-frequency experiments. Tesla moved there to study the conductive nature of low pressure air, part of his research into wireless transmission of electrical power. The lab possessed the largest Tesla coil ever built, in diameter, which was a preliminary version of the magnifying transmitter planned for installation in the Wardenclyffe Tower. Upon his arrival, he told reporters that he planned to conduct wireless telegraphy experiments, transmitting signals from Pikes Peak to Paris. He produced artificial lightning, with discharges consisting of millions of volts and up to long. People walking along the street observed sparks jumping between their feet and the ground. Sparks sprang from water line taps when touched. Light bulbs within of the lab glowed even when turned off. Horses in a livery stable bolted from their stalls after receiving shocks through their metal shoes. Butterflies were electrified, swirling in circles with blue halos of St. Elmo's fire around their wings. While experimenting, Tesla inadvertently faulted a power station generator, causing a power outage. In August 1917, Tesla explained what had happened in The Electrical Experimenter: "As an example of what has been done with several hundred kilowatts of high frequency energy liberated, it was found that the dynamos in a power house away were repeatedly burned out, due to the powerful high frequency currents set up in them, and which caused heavy sparks to jump through the windings and destroy the insulation!" During his time at his laboratory Tesla observed unusual signals from his receiver which he concluded might be communications from another planet. He mentioned them in a letter to reporter Julian Hawthorne at the Philadelphia North American on 8 December 1899 and in a December 1900 letter about possible discoveries in the new century to the Red Cross Society where he referred to messages "from another world" that read "1 ... 2 ... 3 ...". Reporters treated it as a sensational story and jumped to the conclusion Tesla was hearing signals from Mars. He expanded on the signals he heard in a 9 February 1901 Collier's Weekly article "Talking With Planets" where he said it had not been immediately apparent to him that he was hearing "intelligently controlled signals" and that the signals could come from Mars, Venus, or other planets. It has been hypothesized that he may have intercepted Marconi's European experiments in July 1899—Marconi may have transmitted the letter S in a naval demonstration, the same three impulses that Tesla hinted at hearing in Colorado—or signals from another experimenter in wireless transmission. On 7 January 1900 Tesla made his final entry in his journal while in Colorado Springs. In 1904 Tesla was sued for unpaid bills in Colorado Springs, his lab was torn down in that year, and its contents were sold two years later in an auction at the court house to satisfy his debts.
