10 most difficult tech­ni­cal riddles

Cranberry glass or 'Gold Ruby' glass is a red glass made by adding gold salts or colloidal gold to molten glass. The glass is typically hand blown or molded. Legend holds that cranberry glass was first discovered when a noble tossed a gold coin into a mixture of molten glass

Argentina maintains the most permanent polar stations - 6, Chile - 5, Russia - 5.

On May 15, 1718, Englishman James Puckle patented his machine gun, the world's first! You may have thought the Gatling gun or the Maxim machine gun was the first machine gun, but depending on how you define “machine gun” James Puckle, Esq. (yes, he was a lawyer) got there first.

The Borchardt C-93 semi-automatic pistol was designed by Hugo Borchardt in 1893 based upon the Maxim toggle-bolt design.. With about 1,100 manufactured by Loewe and nearly 2,000 more produced by Deutsche Waffen und Munitionsfabriken, the Borchardt C-93 was the first mass-produced semi-automatic pistol.

Mary Anderson (1866 -1953) was an American real estate developer, rancher, viticulturist and inventor of the windshield wiper blade. In November 1903 Anderson was granted her first patent for an automatic car window cleaning device controlled from inside the car, called the windshield wiper. In 1922, Cadillac became the first car manufacturer to adopt them as standard equipment.

Founded in 1976, today Acer is one of the world’s top ICT companies and has a presence in over 160 countries. As Acer looks into the future, it is focused on enabling a world where hardware, software and services will infuse with one another to open up new possibilities for consumers and businesses alike. The etymology of the company's name comes from the Latin word "acer" meaning "eager, vigorous, ".

Cementite (or iron carbide) is a compound of iron and carbon, more precisely an intermediate transition metal carbide with the formula Fe3C. By weight, it is 6.67% carbon and 93.3% iron. It has an orthorhombic crystal structure.

A tachymeter or tacheometer is a type of theodolite used for rapid measurements and determines, electronically or electro-optically, the distance to target. The principles of action are similar to those of rangefinders.

The French ironclad La Gloire ("The Glory") was the first ocean-going ironclad, developed after the Crimean War and launched during 1859. However Gloire was soon itself rendered obsolete by the launching during 1860 of the British HMS Warrior, the world's first iron-hulled ironclad warship.

Myron Krueger is an American computer artist who developed early interactive works. He is also considered to be one of the first generation virtual reality and augmented reality researchers. Krueger went on to develop Metaplay, an integration of visuals, sounds, and responsive techniques into a single framework. In 1971, his "Psychic space" used a sensory floor to perceive the participants' movements around the environment.