Eureka (word)
The exclamation 'Eureka!' is attributed to the ancient Greek scholar Archimedes. He reportedly proclaimed "Eureka! Eureka!" after he had stepped into a bath and noticed that the water level rose, whereupon he suddenly understood that the volume of water displaced must be equal to the volume of the part of his body he had submerged. (This relation is "not" what is known as Archimedes' principle—that deals with the "upthrust" experienced by a body immersed in a fluid.) He then realized that the volume of irregular objects could be measured with precision, a previously intractable problem. He is said to have been so eager to share his discovery that he leapt out of his bathtub and ran naked through the streets of Syracuse.
Tachanka
There are at least two plausible hypotheses about origin of the word "tachanka". The etymological dictionary of Vasmer suggests that the word derives from Ukrainian "netychanka" ("нетичанка"), Polish "najtyczanka", a type of a carriage named after the town of Neutitschein, now Nový Jičín in the Czech Republic. According to another opinion, it is a Ukrainian diminutive, or endearing form of the word "tachka" (, meaning 'wheelbarrow'). Still another opinion is that it is a contracted word 'tavrichanka' for rugged carriages known in Southern Ukraine and Crimea, derived from the name "Taurida" for this area. However the latter derivation is dubious because the 'tavrichanka', a large, rugged agricultural carriage, is of completely different design.