detector in 1908, which stood for "PERfect pIcKard cONtact". Use during the wireless telegraphy era Guglielmo Marconi developed the first practical wireless telegraphy transmitters and receivers in 1896, and radio began to be used for communication around 1899. The coherer was used as detector for the first 10 years, until around 1906. During the wireless telegraphy era prior to 1920, there was virtually no broadcasting; radio served as a point-to-point text messaging service. Until the triode vacuum tube began to be used around World War I, radio receivers had no amplification and were powered only by the radio waves picked up by their antennae. Long distance radio communication depended on high power transmitters (up to 1 MW), huge wire antennas, and a receiver with a sensitive detector. Crystal detectors were invented by several researchers at about the same time. Braun began to experiment with crystal detectors around 1899, around when Bose patented his galena detector. Pickard invented his silicon detector in 1906. Also in 1906 Henry Harrison Chase Dunwoody, a retired general in the U.S. Army Signal Corps, patented the silicon carbide (carborundum) detector, Braun patented a galena cat whisker detector in Germany, and L. W. Austin invented a silicon–tellurium detector. Around 1907 crystal detectors replaced the coherer and electrolytic detector to become the most widely used form of radio detector. Until the triode vacuum tube began to be used during World War I, crystals were the best radio reception technology, used in sophisticated receivers in wireless telegraphy stations, as well as in homemade crystal radios. In transoceanic radiotelegraphy stations elaborate inductively coupled crystal receivers fed by mile long wire antennas were used to receive transatlantic telegram traffic. Much research went into finding better detectors and many types of crystals were tried. The goal of researchers was to find rectifying crystals that were less fragile and sensitive to vibration than galena and pyrite. Another desired property was tolerance of high currents; many crystals would become insensitive when subjected to discharges of atmospheric electricity from the outdoor wire antenna, or current from the powerful spark transmitter leaking into the receiver. Carborundum proved to be the best of these; it could rectify when clamped firmly between flat contacts. Therefore, carborundum detectors were used in shipboard wireless stations where waves caused the floor to rock, and military stations where gunfire was expected. In 1907–1909, George Washington Pierce at Harvard conducted research into how