Also in 1868, several mixed friction-influence machine were developed, including the Kundt machine and the Carré machine. In 1866, the Piche machine (or Bertsch machine) was developed. In 1869, H. Julius Smith received the American patent for a portable and airtight device that was designed to ignite powder. Also in 1869, sectorless machines in Germany were investigated by Poggendorff. The action and efficiency of influence machines were further investigated by F. Rossetti, A. Righi, and Friedrich Kohlrausch. E. E. N. Mascart, A. Roiti, and E. Bouchotte also examined the efficiency and current producing power of influence machines. In 1871, sectorless machines were investigated by Musaeus. In 1872, Righi's electrometer was developed and was one of the first antecedents of the Van de Graaff generator. In 1873, Leyser developed the Leyser machine, a variation of the Holtz machine. In 1880, Robert Voss (a Berlin instrument maker) devised a form of machine in which he claimed that the principles of Toepler and Holtz were combined. The same structure become also known as the Toepler-Holtz machine. Wimshurst machine In 1878, the British inventor James Wimshurst started his studies about electrostatic generators, improving the Holtz machine, in a powerful version with multiple disks. The classical Wimshurst machine, that became the most popular form of influence machine, was reported to the scientific community by 1883, although previous machines with very similar structures were previously described by Holtz and Musaeus. In 1885, one of the largest-ever Wimshurst machines was built in England (it is now at the Chicago Museum of Science and Industry). The Wimshurst machine is a considerably simple machine; it works, as all influence machines, with electrostatic induction of charges, which means that it uses even the slightest existing charge to create and accumulate more charges, and repeats this process for as long as the machine is in action. Wimshurst machines are composed of: two insulated disks attached to pulleys of opposite rotation, the disks have small conductive (usually metal) plates on their outward-facing sides; two double-ended brushes that serve as charge stabilizers and are also the place where induction happens, creating the new charges to be collected; two pairs of collecting combs, which are, as the name implies, the collectors of electrical charge produced by the machine; two Leyden Jars, the capacitors of the machine; a pair of electrodes, for the transfer of charges once they have been sufficiently accumulated. The simple structure