Traveller's cheques and credit cards (American Express, Visa, Mastercard) are exchanged for Vietnamese dong at the banks. Cards can be used in travel agencies, hotels, and major restaurants. US currency is exchanged for Vietnamese dong and treasury notes in banks, exchange bureaus, hotels, and jewellery shops.
Nikola Tesla designed the first hydroelectric power plant at Niagara Falls, New York which started producing electrical power in 1895. This was the beginning of the electrification of the United States and the rest of the world. Today, Teslaâs AC electricity is lighting and powering the globe.
With help from Mark Twain, Tesla nearly discovered X-rays. Twain and Tesla became friends in the 1890s, thanks in part to Twainâs lifelong fascination with technology and new inventions. Visiting Teslaâs lab late one night, Twain posed for one of the first photographs to be lit by incandescent light.